The damping-off and stem rot disease syndrome is harmful to many cultivated crops. Damping-off and stem rot caused by Sclerotium rolfsii Sacc. on cowpea results in yield losses with serious socio-economic implications. The objectives of the present study were to investigate the occurrence of the diseases in Benin, study etiology and factors influencing the diseases, and develop strategies for the control of the diseases in the field. Results showed that the diseases are distributed countrywide. Sclerotium rolfsii was the main causal agent but minor pathogens, namely Pythium sp., Rhizoctonia solani Kühn and Phoma pomorum Thüm were also recorded. In the Ouémé valley, the diseases were favoured by soil moisture and S. rolfsii initial inoculum that were higher closer to the river. Sclerotium rolfsii isolates collected in the valley showed genetic diversity in terms of pathogenicity, mycelial compatibility groups and ITS rDNA sequences. A paper-based screening method was found to be a rapid laboratory method for screening for resistance in cowpea cultivars. Furtheremore, Moringa oleifera L. leaf extracts, Trichoderma Kd 63 and Trichoderma IITA 508 significantly reduced the disease incidence. The best disease control was recorded in the field when M. oleifera seed treatment was integrated with a soil sprinkle of Trichoderma. The present work provides information on damping-off and stem rot of cowpea in Benin and control strategies for ecologically sustainable cowpea production. / Thesis (DPhil (Microbiology and Plant Pathology))--University of Pretoria, 2006. / Microbiology and Plant Pathology / unrestricted

Spodoptera frugiperda (J.E. Smith) tem sido uma das pragas mais importantes da cultura do milho no Paraguai e Brasil. Este trabalho foi realizado para subsidiar programas de manejo de resistência no Paraguai, reconhecendo-se a proximidade das fronteiras agrícolas desse país com Brasil e a alta capacidade de dispersão de S. frugiperda. Para tanto, foram realizados estudos de caracterização da suscetibilidade aos inseticidas lufenuron e flubendiamide e de diversidade genética e o fluxo gênico em populações de S. frugiperda coletadas nas principais regiões produtoras de milho do Paraguai e de dois Estados fronteiriços do Brasil (Mato Grosso do Sul e Paraná). O método de bioensaio para a caracterização das linhas-básica de suscetibilidade foi o de tratamento superficial da dieta artificial com o inseticida. As variações na suscetibilidade a lufenuron e flubendiamide entre as populações de S. frugiperda testadas foram baixas (< 4 vezes), comparando-se as populações das regiões Oriental e Ocidental do Paraguai que apresentam caraterísticas climáticas distintas ou entre as populações do Paraguai e do Brasil. Para o monitoramento da suscetibilidade de populações de S. frugiperda no Paraguai foram definidas as doses diagnósticas, baseada na DL99, de 0,16 &mu;g de lufenuron.cm-2 (equivalente a 10 &mu;g de lufenuron.mL-1 de água) e 2,84 &mu;g de flubendiamide.cm-2 (180 &mu;g de flubendiamide.mL-1 de água). Mediante o uso de 12 loci microssatélites, foram verificadas maior diversidade genética dentro das populações (87,70%) quando comparada entre as populações de cada país (9,91%) e entre países (2,39%). Sendo assim, não foi constatada alta estruturação genética entre as populações de S. frugiperda coletadas no Paraguai e Brasil. As populações do Paraguai mostraram-se mais distintas entre si quando comparadas com as populações do Brasil. Nossos resultados apontam baixa estruturação genética e moderado/alto fluxo gênico entre as localidades de coleta de populações de S. frugiperda e entre as populações do Paraguai e Brasil. Os resultados obtidos na presente pesquisa servirão para a implementação de um programa de manejo da resistência de S. frugiperda a inseticidas no Paraguai, com ênfase na necessidade de ações no âmbito regional considerando os estados fronteiriços do Brasil. / Spodoptera frugiperda (J.E. Smith) has been one of the most important corn pests in Paraguay and Brazil. This research was conducted to collect information to insect resistance management programs in Paraguay considering the proximity of agricultural borders of this country with Brazil and the high dispersal capacity of S. frugiperda. We conducted studies to characterize the susceptibility to the insecticides lufenuron e flubendiamide and to evaluate the genetic diversity and gene flow among S. frugiperda populations collected from major corn-producing regions in Paraguay and two frontier States of Brazil (Mato Grosso do Sul and Paraná). The bioassay method to characterize the baseline susceptibility was the diet surface treatment with the insecticide. The variation in the susceptibility to lufenuron and flubendiamide among S. frugiperda populations tested was low (< 4-fold) by comparing populations from Estearn and Western regions of Paraguay with distinct climatic conditions or populations from Paraguay and Brazil. For susceptibility monitoring to lufenuron and flubendiamide in S. frugiperda populations in Paraguay, we defined the diagnostic doses based on LD99 of 0.16 &mu;g of lufenuron.cm-2 (equivalent to 10 &mu;g of lufenuron.mL-1 of water) and 2,84 &mu;g of flubendiamide.cm-2 (180 &mu;g of flubendiamide.mL-1 of water). Using 12 microsatellite loci, higher genetic diversity within populations (87.70%) than among populations within each country (9.91%) and between countries (2.39%). Thus, there was no high genetic structure between S. frugiperda populations collected in Paraguay and Brazil. The populations of S. frugiperda from Paraguay were more distinct among themselves when compared with the populations from Brazil. Our results suggest low genetic structure and moderate/high gene flow among different sampling locations of S. frugiperda populations as well as between populations from Paraguay and Brazil. The results obtained in this research will support the implementation of resistance management programs of S. frugiperda to inseticides in Paraguay with focus on the need of plan of actions at regional level considering the border States of Brazil.

Submitted by Ricardo Cedraz Duque Moliterno (ricardo.moliterno@uefs.br) on 2016-01-26T21:56:33Z No. of bitstreams: 1 TESE_Anderson_FINAL.pdf: 3427530 bytes, checksum: 027d12f66415d71dc327e860609665fe (MD5) / Made available in DSpace on 2016-01-26T21:56:33Z (GMT). No. of bitstreams: 1 TESE_Anderson_FINAL.pdf: 3427530 bytes, checksum: 027d12f66415d71dc327e860609665fe (MD5) Previous issue date: 2015-06-29 / Conselho Nacional de Pesquisa e Desenvolvimento Cient?fico e Tecnol?gico - CNPq / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Funda??o de Amparo ? Pesquisa do Estado da Bahia - FAPEB / Eplingiella fruticosa (Salzm. Ex Benth.) Harley & JFB Pastore is an aromatic species, native, occurring in six states in northeastern Brazil (Bahia, Sergipe, Pernambuco, Paraiba, Rio Grande do Norte and Cear?). Popularly known as "alecrim de vaqueiro", is commonly found in street markets of the region and used to combat pain and seizures. Reviews in mice and in vitro studies show analgesic activity, vasodilating, cardioprotetiva, anti-inflammatory and larvicidal of its essential oil and of different types of the leaves extract. Recent studies show great variability in essential oil chemical composition of E. fruticosa, related to soil and climatic conditions and different plant organs. Thus, the species has great potential for exploration both agronomic, and by pharmaceutical companies. The aim of this study was to evaluate the vegetative propagation capacity and characterize previously Eplingiella genotypes, through morphological, agronomic, phytochemicals and molecular data. In Chapter I, two experiments were conducted: the first tested the effect of three substrates and the second evaluated five concentrations of IBA and three periods of cultivation. The design was a randomized block design with four replications. We evaluated survival percentage (% S), percentage of rooted cuttings (% EE), root length (CRE), number of shoots (NBE), dry mass of leaves (MSF), root dry weight (MSR) and total dry matter (MST). In Chapter II, twelve genotypes were collected, propagated vegetatively and transplanted. Twelve months after transplantation were assessed 12 quantitative traits, eight morphological and agronomic four. In Chapter III, the total DNA was extracted, then 20 primers were tested, of which nine were selected because they have better electrophoretic profiles agarose gel (2%). The binary matrix was computed in GEOCOMPAR II. It is estimated the diversity of the genetic structure parameters and the data were subjected to Bayesian analysis, and Neighbor-joining dendrogram and principal component analysis (PCA) based on matrix of Nei distances. And in Chapter IV, samples of 100g of leaves each repetition per genotype were used in the essential oil hydrodistillation in Clevenger type apparatus for three hours, quantifying the content. The identification of the compounds and their contents was performed by GC (FID) and GC / MS data 15 and the major compounds were used in diversity analysis. They have been made to cluster analysis and canonical variables, using as dissimilarity measure the Mahalanobis distance (D2). In the first experiment of Chapter I, significant differences were found for CRE, NBE, MSF, MSR and MST, with the best performance for the commercial substrate. In the second, positive effects have been identified both the addition of AIB as the cultivation time on the CRE variables, NBE, MSF and MSR, reaching maximum increment to the estimated concentration of 1.5 g L-1, at 60 days of cultivation. In Chapter II, there was significant variation by F test (p <0.01) for the CF features, LF, CBD, CBE, LP, and MFF MSF. The genotypes formed two groups for almost all variables, by Scott-Knott test (p <005), except for LP, which formed three. The EF002 and EF003 genotypes presented the highest levels for almost all variables. There was the formation of three groups for both UPGMA and for the canonical variables (CV). The characteristics that most contributed to the formation of groups were CBE, MFF and CF. The genotypes EF002, EF003, EF005 and EF012 stood out because they have higher genetic distances. In CHAPTER III, primers produced 131 polymorphic bands. The diversity index of Nei (Ne) ranged between 0.31 and 0.39, while Shannon (I) ranged between 0.33 and 0.48. The percentage coefficient of genetic differentiation (Gst) was 0.29. In AMOVA most of the variation was within populations (69%), while among populations was 27% and 4% among species, indicating a good genetic structure. The average value of Fst was 0.175, demonstrating intermediate differentiation between populations. The structure of the Bayesian analysis method revealed three possibilities for the formation of groups (K = 2; = 6; 8 =;), however, it presented many migrants and high level of mixing individuals. The dendrogram generated by the Neighbor-Joining method confirmed the formation of two groups, with good support for major clades (100%). PCA analysis in the first two axis explained 21.06% of the total variation among populations. Finally, in Chapter IV, the genotypes were classified into four clusters: 1 - EF001 genotypes, EF006, EF007, EF008, EF010, EF011 and EF012 with E-caryophyllene and bicyclogermacrene as major; 2 - EF002 and EF003 genotypes, with the majority same as the previous group, however, percentage with average about 30% higher; 3 - EF004 and EF005 genotypes that showed a greater production of E-caryophyllene; and 4 - with EF009 genotype, forming a single group to present ?-pinene as balanced majority and percentage among the rest. This result was confirmed by canonical variables, which explained 76% of the variation. The bicyclogermacrene compounds, 1,8-cineol, ?-copaene and spathulenol represented the most important variables for analysis. / Eplingiella fruticosa (Salzm. ex Benth.) Harley & J.F.B. Pastore ? uma esp?cie arom?tica, nativa, que ocorre em seis estados do nordeste brasileiro (Bahia, Sergipe, Pernambuco, Para?ba, Rio Grande do Norte e Cear?). Popularmente conhecida como ?alecrim de vaqueiro?, ? comumente encontrada em feiras livres da regi?o e utilizada no combate a dores e convuls?es. Avalia??es em camundongos e in vitro comprovam atividades analg?sicas, vasodilatadora, cardioprotetiva, antinflamat?ria e larvicida do seu ?leo essencial e de diferentes tipos de extrato de suas folhas. Estudos recentes apontam grande variabilidade na composi??o qu?mica do ?leo essencial de E. fruticosa, relacionada ?s condi??es edafoclim?ticas e aos diferentes ?rg?os vegetais. Sendo assim, a esp?cie apresenta grande pot?ncial de explora??o tanto agron?mica, quanto por ind?strias farmac?uticas. O objetivo geral deste estudo foi avaliar a capacidade de propaga??o vegetativa e caracterizar, previamente, gen?tipos de E. fruticosa, por meio de dados morfol?gicos, agron?micos, fitoqu?micos e moleculares. No CAP?TULO I, foram conduzidos dois experimentos: o primeiro testou o efeito de tr?s substratos e o segundo avaliou cinco concentra??es de AIB e tr?s per?odos de cultivo. O delineamento foi em blocos casualizado, com quatro repeti??es. Avaliou-se percentagem de sobreviv?ncia (%S), percentagem de estacas enraizadas (%EE), comprimento da raiz (CRE), n?mero de brota??es (NBE), massa seca de folhas (MSF), massa seca de raiz (MSR) e massa seca total (MST). No CAP?TULO II, doze gen?tipos foram coletados, propagados vegetativamente e transplantados. Doze meses ap?s o transplante foram avaliadas 12 caracter?sticas quantitativas, sendo oito morfol?gicase quatro agron?micas. No CAP?TULO III, o DNA total foi extra?do, em seguida 20 iniciadores foram testados, dos quais nove foram selecionados por apresentarem melhores perfis eletrofor?ticos em gel de agarose (2%). A matriz bin?ria foi computada no GEOCOMPAR II. Estimou-se os par?metros de diversidadee a estrutura gen?tica os dados foram submetidos ? an?lise Bayesiana, al?m de dendrograma Neighbor-joining e an?lise de componentes principais (PCA) com base na matriz de dist?ncias de Nei. E no CAP?TULO IV, amostras de 100g de folhas de cada repeti??o por gen?tipo foram utilizadas na hidrodestila??o do ?leo essencial, em aparelho tipo clevenger, durante tr?s horas, quantificando-se o teor. A identifica??o dos compostos e seus teores foi realizada por CG (DIC) e CG/EM e os dados de 15 compostos majorit?rios foram utilizados nas an?lises de diversidade. Foram procedidas an?lise de agrupamento e de vari?veis can?nicas, utilizando como medida de dissimilaridade a dist?ncia generalizada de Mahalanobis (D2).No primeiro experimento do CAP?TULO I, foram verificadas diferen?as significativas para CRE, NBE, MSF, MSR e MST, com melhor desempenho para o substrato comercial. No segundo, foram identificados efeitos positivos tanto da adi??o de AIB quanto dos tempos de cultivo sobre as vari?veis CRE, NBE, MSF e MSR, atingindo incremento m?ximo com a concentra??o estimada de 1,5 g L-1, aos 60 dias de cultivo. No CAP?TULO II, houve varia??o significativa, pelo teste de F (p<0,01), para as caracter?sticas CF, LF, CBD, CBE, LP, MFF e MSF. Os gen?tipos formaram dois grupos para quase todas as vari?veis, pelo teste de Scott-Knott (p<005), exceto para LP, que formou tr?s. Os gen?tipos EF002 e EF003 apresentaram as maiores m?dias para quase todas vari?veis. Houve a forma??o de tr?s grupos, tanto para UPGMA quanto para as vari?veis can?nicas (VC). As caracter?sticas que mais contribu?ram para a forma??o dos grupos foram CBE, MFF e CF. Os gen?tipos EF002, EF003, EF005 e EF012 se destacaram por apresentarem maiores dist?ncias gen?ticas. No CAP?TULO III, os iniciadores produziram 131 bandas polim?rficas. O ?ndice de diversidade de Nei (Ne) variou entre 0,31 e 0,39, enquanto Shannon (I) variou entre 0,33 e 0,48. O percentual do coeficiente de diferencia??o gen?tica (Gst) foi de 0,29. Na AMOVA a maior parte da varia??o ficou dentro das popula??es (69%), enquanto entre popula??es foi de 27% e entre esp?cies de 4%, indicando uma boa estrutura??o gen?tica. O valor m?dio de Fst foi 0,175, demonstrando diferencia??o intermedi?ria entre as popula??es. As an?lises de estrutura pelo m?todo Bayesiano revelou tr?s possibilidades de forma??o de grupos (K=2;=6;=8;), no entanto, apresentou muitos indiv?duos migrantes e elevado n?vel de miscigena??o. O dendograma gerado pelo m?todo de Neighbor-Joining confirmou a forma??o de dois grupos, com boa sustenta??o para os principais clados (100%). Na an?lise de PCA os dois primeiros axis explicaram 21,06% da varia??o total entre as popula??es. Por fim, no CAP?TULO IV, os gen?tipos foram classificados em quatro clusters: 1 - gen?tipos EF001, EF006, EF007, EF008, EF010, EF011 e EF012, com E-cariofileno e biciclogermacreno como majorit?rios; 2 - gen?tipos EF002 e EF003, com os mesmos majorit?rios que o grupo anterior, no entanto, com percentuais m?dios cerca de 30% superiores; 3 - gen?tipos EF004 e EF005, que evidenciaram uma maior produ??o de E-cariofileno; e 4 - com gen?tipo EF009, formando um grupo isolado por apresentar ?-pineno como majorit?rio e percentuais equilibrados entre os demais. Esse resultado foi confirmado pelas Vari?veis Can?nicas, que explicou 76% da varia??o. Os compostos biciclogermacreno, 1,8-cineol, ?-copaeno e espatulenol representaram as vari?veis de maior import?ncia para a an?lise.

<p>Vrsta&nbsp;<em> Ambrosia&nbsp; artemisiifolia&nbsp; L.&nbsp;</em> (fam.&nbsp; Asteraceae)&nbsp; je&nbsp; jedna&nbsp; od&nbsp; najagresivnijih&nbsp; invazivnih&nbsp;biljaka&nbsp; kako&nbsp; u&nbsp; Evropi,&nbsp; tako&nbsp; i&nbsp; na&nbsp; globalnom&nbsp; nivou.&nbsp; Kao&nbsp; korovska&nbsp; vrsta&nbsp; uzrokuje&nbsp; velike&nbsp;ekonomske&nbsp; gubitke&nbsp; redukujući&nbsp; prinos&nbsp; poljoprivrednih&nbsp; kultura,&nbsp; a&nbsp; njena&nbsp; masovna&nbsp; produkcija&nbsp;polena stvara ozbiljne alergijske probleme kod ljudi. Kao invazivna vrsta, predstavlja dobar&nbsp;model za proučavanje procesa uključenih u biolo&scaron;ke invazije, koje se danas prepoznaju kao&nbsp;deo globalnih promena, predstavljajući jednu od glavnih pretnji biodiverzitetu, funkcionisanju&nbsp;ekosistema,&nbsp; poljoprivredi,&nbsp; ali&nbsp; i&nbsp; ljudskom&nbsp; zdravlju.&nbsp; U&nbsp; Evropi,&nbsp; ambrozija&nbsp; je&nbsp; &scaron;iroko&nbsp;rasprostranjena,&nbsp; ali&nbsp; jedno&nbsp; od&nbsp; područja&nbsp; sa&nbsp; najvećom&nbsp; incidencom&nbsp; ovog&nbsp; invazivnog&nbsp; korova&nbsp; je&nbsp;Panonska&nbsp; nizija.&nbsp; Po&nbsp; svom&nbsp; položaju,&nbsp; kao&nbsp; i&nbsp; karakteristikama&nbsp; samog&nbsp; područja,&nbsp; ovaj&nbsp; region&nbsp;predstavlja&nbsp; povoljno&nbsp; stani&scaron;te&nbsp; kako&nbsp; za&nbsp; introdukciju&nbsp; ambrozije&nbsp; iz&nbsp; različitih&nbsp; pravaca,&nbsp; tako&nbsp; i&nbsp; za&nbsp;njenu brzu ekspanziju u pomenutom području i &scaron;ire.&nbsp; U proteklih 30-40 godina ambrozija se&nbsp;&scaron;iri&nbsp; na&nbsp; peripanonsko&nbsp; područje,&nbsp; tačnije&nbsp; ka&nbsp; centralnim&nbsp; i&nbsp; južnim&nbsp; delovima&nbsp; Srbije.&nbsp; Uzimajući&nbsp; u&nbsp;obzir sve činjenice,&nbsp; cilj ovog istraživanja je bio genetička karakterizacija populacija ambrozije&nbsp;<br />sa područja Panonske nizije i peripanonskog prostora centralnog&nbsp; dela Balkanskog poluostrva.&nbsp;U&nbsp; svrhu&nbsp; ovoga,&nbsp; upotrebljeni&nbsp; su&nbsp; jedni&nbsp; od&nbsp; najpopularnijih&nbsp; i &nbsp;ajinformativnijih&nbsp; molekularnih&nbsp;markera u polju populacione genetike, mikrosateliti. Na području Panonske nizije utvrđen je&nbsp;visok nivo genetičke varijabilnosti i nizak nivo genetičke diferencijacije i struktuiranosti među&nbsp;ispitivanim&nbsp; populacijama, a najverovatnije kao posledica multiplih introdukcija i intenzivnog&nbsp;protoka gena među populacijama ispitivanog regiona. Suprotno, populacije sa peripanonskog&nbsp;prostora&nbsp; centralnog&nbsp; Balkana&nbsp; su&nbsp; pokazale&nbsp; niži&nbsp; nivo&nbsp; genetičkog&nbsp; diverziteta&nbsp; u&nbsp; odnosu&nbsp; na&nbsp;panonske populacije, sa izraženom inter-populacionom diferencijacijom. Potvrđeno je &scaron;irenje&nbsp;ambrozije&nbsp; u&nbsp; pravcu&nbsp; sever-jug&nbsp; na&nbsp; području&nbsp; peripanonskog&nbsp; prostora,&nbsp; kao&nbsp; i&nbsp; poreklo&nbsp; ovih&nbsp;populacija&nbsp; od&nbsp; populacija&nbsp; iz&nbsp; regiona&nbsp; Panonske&nbsp; nizije,&nbsp; ali&nbsp; bez&nbsp; isključivanja&nbsp; mogućeg&nbsp; upliva&nbsp;ambrozije&nbsp; iz&nbsp; drugih&nbsp; pravaca.&nbsp; Ova&nbsp; saznanja&nbsp; doprinose&nbsp; rasvetljavanju&nbsp; procesa&nbsp; introdukcije&nbsp; i&nbsp;ekspanzije&nbsp; ispitivane&nbsp; invazivne&nbsp; vrste&nbsp; na&nbsp; ovom&nbsp; području&nbsp; Evrope.&nbsp; Utvrđen&nbsp; visok&nbsp; potencijal&nbsp; u&nbsp;ekspanziji ambrozije i potencijalni pravci &scaron;irenja u ispitivanom području, mogu da doprinesu&nbsp;predviđanju dalje potencijalne ekspanzije ove vrste, &scaron;to bi moglo unaprediti mere kontrole i&nbsp;strategiju za suzbijanje &scaron;irenja ambrozije.</p> / <p><em>Ambrosia&nbsp; artemisiifolia&nbsp;</em> L.&nbsp; (fam.&nbsp; Asteraceae)&nbsp; is&nbsp; one&nbsp; of&nbsp; the&nbsp; most&nbsp; aggressive&nbsp; invasive&nbsp; plant&nbsp;species&nbsp; in&nbsp; Europe&nbsp; and&nbsp; globally.&nbsp; As&nbsp; weed&nbsp; species,&nbsp; common&nbsp; ragweed&nbsp; causes&nbsp; great&nbsp; economic&nbsp;losses by reducing the yield of agricultural crops, and its mass production&nbsp; of pollen produces&nbsp;severe allergic problems in humans. As an invasive species,&nbsp; <em>Ambrosia artemisiifolia&nbsp;</em> is&nbsp; a good&nbsp;model for studying the processes of biological invasions, which are today recognized as part&nbsp;of&nbsp; global&nbsp; changes,&nbsp; presenting&nbsp; a&nbsp; major&nbsp; threat&nbsp; to&nbsp; biodiversity,&nbsp; the&nbsp; functioning&nbsp; of &nbsp; ecosystems,&nbsp;agriculture and human health. In Europe, <em>Ambrosia artemisiifolia</em> is widespread, but one of the&nbsp;most&nbsp; infested&nbsp; area&nbsp; is&nbsp; the&nbsp; Pannonian&nbsp; Plain.&nbsp; According&nbsp; to&nbsp; location&nbsp; and&nbsp; characteristics&nbsp; of&nbsp; the&nbsp;area,&nbsp; this&nbsp; region&nbsp; represents&nbsp; a&nbsp; favorable&nbsp; habitat&nbsp; for&nbsp; introduction&nbsp; of&nbsp; common&nbsp; ragweed&nbsp; from&nbsp;different&nbsp; directions&nbsp; and&nbsp; rapid&nbsp; expansion&nbsp; in&nbsp; these&nbsp; areas&nbsp; as&nbsp; well&nbsp; as&nbsp; further.&nbsp; In&nbsp; the&nbsp; past&nbsp; 30-40&nbsp;years,&nbsp; common&nbsp; ragweed&nbsp; was&nbsp; spreading&nbsp; across&nbsp; Peripannonian&nbsp; region,&nbsp; more&nbsp; precisely,&nbsp; to&nbsp; the&nbsp;Central and Southern parts of Serbia. According the facts, the aim of this study was the genetic&nbsp;characterization&nbsp; of&nbsp; populations&nbsp; of&nbsp; <em>Ambrosia&nbsp; artemisiifolia&nbsp;</em> from&nbsp; the&nbsp; Southern&nbsp; part&nbsp; of&nbsp; the&nbsp;Pannonian Plain and the&nbsp; Peripannonian region of the Central Balkan.&nbsp; One of the most popular&nbsp;and most informative molecular markers in&nbsp; population genetics, microsatellites&nbsp; were&nbsp; used. In&nbsp;the area of the Pannonian Plain, a high level of&nbsp; genetic variability and low&nbsp; level of&nbsp; genetic&nbsp;differentiation and structure&nbsp; among the study population have detected, probably as a&nbsp; result of&nbsp;multiple&nbsp; introduction&nbsp; and&nbsp; intensive&nbsp; gene&nbsp; flow&nbsp; between&nbsp; populations.&nbsp; In&nbsp; the&nbsp; other&nbsp; hand,&nbsp; the&nbsp;populations from the Peripannonian region have shown lower level of genetic diversity related&nbsp;to&nbsp; populations&nbsp; from&nbsp; Pannonin&nbsp; Plain,&nbsp; with&nbsp; moderate&nbsp; level&nbsp; of&nbsp; inter-population&nbsp; differentiation.&nbsp;Obtained&nbsp; results&nbsp; have&nbsp; confirmed&nbsp; that&nbsp; the&nbsp; spread&nbsp; of&nbsp; common&nbsp; ragweed&nbsp; across&nbsp; Peripannonian&nbsp;region was&nbsp; in the north-south direction, as &nbsp;well as that the populations from the considered&nbsp;area originated from the populations of Pannonian Plain.&nbsp; However, in this claim we can not&nbsp;exclude&nbsp; the&nbsp; possible&nbsp; influence&nbsp; of&nbsp; <em>Ambrosia&nbsp; artemisiifolia</em>&nbsp; from&nbsp; other&nbsp; directions.&nbsp; This&nbsp; study&nbsp;contributes&nbsp; to&nbsp; better understuding of&nbsp; the process of introduction and expansion of&nbsp; <em>Ambrosia&nbsp;artemisiifolia&nbsp;</em> in&nbsp; considered part&nbsp; of Europe.&nbsp; Detected&nbsp; high potential for &nbsp;expansion of&nbsp; common&nbsp;ragweed and possible directions of spreading in the study area, can contribute to the prediction&nbsp;of&nbsp; potential&nbsp; further&nbsp; expansion&nbsp; of&nbsp; <em>Ambrosia&nbsp; artemisiifolia</em>,&nbsp; which&nbsp; could&nbsp; improve&nbsp; control&nbsp;measures and strategies for preventing the spreading of this invasive species.&nbsp;</p>

<p>Predmet ovog istraživanja je varijabilnost taksona&nbsp; <em>Ornithogalum umbellatum</em>&nbsp; L. 1753. (Hyacinthaceae) na području Srbije i Mađarske. Ovaj najpoznatiji i najrasprostranjeniji predstavnik roda&nbsp;<em> Ornithogalum&nbsp;</em> L. izučava se dugi niz godina sa različitih aspekata: kao gajena ba&scaron;tenska vrsta i kao invazivni korov; kao otrovna biljka i potencijalno lekovita. Sa ekolo&scaron;kog aspekta&nbsp; ove biljke su značajne kao&nbsp; domaćini insektima polinatorima koji su vi&scaron;estruko i u različitim fazama razvića vezani za ove lukovičaste geofite. Veliki areal&nbsp; i prilagođenost različitim tipovima stani&scaron;ta uzrokuju značajnu varijabilnost, koja rezultuje taksonomskom konfuzijom.&nbsp; Jedan od razloga za&nbsp; istorijski prepoznatljive taksonomski i filogenetski nerazja&scaron;njene relacije&nbsp; su&nbsp; područja sa prirodnim stani&scaron;tima populacija&nbsp;<em> O.&nbsp; umbellatum</em>&nbsp; čijem izučavanju nije posvećeno dovoljno pažnje. Jedno od takvih je i ovde istraživano područje. Kako je u Flori Srbije kao podvrsta&nbsp;<em> O. umbellatum&nbsp;</em> opisan i&nbsp; <em>O. umbellatum&nbsp; subsp.&nbsp; divergens</em>&nbsp; (Boreau), analizama su obuhvaćene i populacije ovog taksona.</p><p>RAPD-PCR metodom ustanovljen je vi&scaron;i nivo genetičkog diverziteta između nego u<br />okviru populacija, bez jasnog geografskog trenda dispozicije ove varijabilnosti. Ovi su<br />rezultati očekivani za poliploidne taksone sa velikim udelom vegetativnog razmnožavanja u reproduktivnoj strategiji biljke, koji su pritom &scaron;iroko rasprostranjeni<br />a u istraživanom području predstavljeni uglavnom relativno udaljenim te izolovanim<br />populacijama.&nbsp; Determinacija genetičke struktuiranosti među ispitivanim&nbsp; genotipovima ukazala je na razdvajanje populacija dva taksona u dva klastera. Rezultate u saglasnosti sa ovim dala&nbsp; je i analiza parametara poprečnih preseka lista, skapusa i plodnika, a ustanovljeni su i diskriminativni anatomski karakteri koji su razdvojili populacije dva taksona. Izdvojeni su pojedini kvantitativni karakteri, kako anatomski tako i morfolo&scaron;ki, koji su&nbsp; najvi&scaron;e doprineli varijabilnosti na interpopulacionom nivou. Pokazana je velika raznolikost morfolo&scaron;kih karaktera i heterogenost populacija&nbsp;<em> O. umbellatum</em>, &scaron;to je u skladu sa podacima u postojećoj litaraturi. Poznato je i da&nbsp; habitus ovih&nbsp; biljaka&nbsp; veoma&nbsp; zavisi&nbsp; od&nbsp; uslova&nbsp; sredine,&nbsp; kao&nbsp; i&nbsp; stadijuma&nbsp; razvića&nbsp; biljke,&nbsp; dok&nbsp; na molekularne&nbsp; markere&nbsp; ovi&nbsp; faktori&nbsp; ne&nbsp; utiču.&nbsp; Sa&nbsp; druge&nbsp; strane,&nbsp; iako&nbsp; primenjena&nbsp; RAPD metoda&nbsp; nije&nbsp; dovoljna&nbsp; za&nbsp; determinaciju&nbsp; filogenetski&nbsp; blisko&nbsp; srodnih&nbsp; taksona&nbsp; poput&nbsp; ovih, pokazala&nbsp; se&nbsp; pouzdanom&nbsp; i&nbsp; efikasnom&nbsp; za&nbsp; ispitivanje&nbsp; diverziteta&nbsp; na&nbsp; populaciono-genetičkom&nbsp; nivou.&nbsp; Stoga&nbsp; je&nbsp; u&nbsp; cilju&nbsp; &scaron;to&nbsp; sveobuhvatnije&nbsp; procene&nbsp; stanja&nbsp; kori&scaron;ćena kombinacija&nbsp; različitih&nbsp; pristupa,&nbsp; koji&nbsp; su&nbsp; dali&nbsp; usagla&scaron;ene&nbsp; rezultate,&nbsp; istovremeno&nbsp; dajući uvid&nbsp; u&nbsp; nivo&nbsp; polimorfnosti&nbsp; i&nbsp; struktuiranosti&nbsp; populacija&nbsp; i&nbsp; ukazujući&nbsp; na&nbsp; jedinstvene&nbsp; oblike<br />varijabilnosti morfo-anatomskih karakteristika</p><p>Sa&nbsp; jedne&nbsp; strane&nbsp; ovo&nbsp; je&nbsp; važno&nbsp; zbog&nbsp; razja&scaron;njenja&nbsp; komplikovane&nbsp; taksonomije,&nbsp; a&nbsp; sa&nbsp; druge zbog&nbsp; značaja&nbsp; ovih&nbsp; biljaka&nbsp; sa&nbsp; aspekta&nbsp; potencijalne&nbsp; koristi&nbsp; odnosno&nbsp; &scaron;tete&nbsp; za&nbsp; čoveka,&nbsp; ali&nbsp; i iz&nbsp; ugla&nbsp; za&scaron;tite&nbsp; biodiverziteta.&nbsp; Uvid&nbsp; u&nbsp; nivo&nbsp; varijabilnosti&nbsp; populacija&nbsp; doprineće adekvatnim&nbsp; strategijama&nbsp; konzervacije&nbsp; i&nbsp; menadžmenta&nbsp; kako&nbsp; ovih&nbsp; biljnih&nbsp; vrsta,&nbsp; tako&nbsp; i insekatskih sa kojima su povezane.</p> / <p>Variability of&nbsp; <em>Ornithogalum umbellatum&nbsp;</em> L. 1753. (Hyacinthaceae) in&nbsp; Serbia and Hungary&nbsp; was analyzed in this research. This most famous and the most&nbsp; widespread taxon in genus <em>Ornithogalum</em> L. has been a research subject for many years for various reasons: as garden plant and invasive weed; for its toxic and pharmaceutical properties. From an ecological point of view those bulbous geophytes&nbsp; are the important host-plants for insect pollinators associated with them in different life stages.&nbsp; Large distribution area and adaptation to diverse habitat types result in significant variability of these plants which is followed by&nbsp; taxonomic confusion. Persisting taxonomic problems arise also from the fact that there are under-investigated regions with native populations of <em>O.</em>&nbsp;<em>umbellatum, </em>such as&nbsp; localities&nbsp; in Serbia and neighbouring countries. Since published floras of these countries&nbsp; include&nbsp; <em>O. umbellatum&nbsp;</em> subsp.&nbsp; <em>divergens</em> (Boreau), analyses involve populations of this taxon as&nbsp; well.</p><p>RAPD-PCR method revealed higher levels of genetic diversity among than within populations, without distinct geographical trend in the disposition of the variability. These results have been expected for polyploid taxa with high levels of vegetative reproduction, widespread and represented mostly with relatively distant and isolated populations in the given region. Genetic structure analyses have separated&nbsp; populations of the two investigated taxa into two clusters. Analyses of the anatomical characteristics of the leaf, scapus and ovary cross-sections have shown results in accordance with those. Discriminative characters which divided populations of the two&nbsp; taxa were determined. Distinctive quantitative characters, both anatomical and morphological, which have contributed the most to the interpopulation variability, were&nbsp; singled out. Great diversity of morphological characters and population heterogeneity&nbsp; of&nbsp; <em>O.&nbsp; umbellatum&nbsp;</em> has been&nbsp; shown, which&nbsp; was&nbsp; already described in literature dealing with the subject. Additionally, the high diversity is explained by the fact that habitus of those plants with very plastic phenotypes is influenced by environmental conditions and life stage of the plant. Those factors do not affect molecular markers; however techniques like RAPD-PCR could not be used independently for&nbsp; characterization&nbsp; of phylogenetically close taxa such as these. Nevertheless, RAPDs proved to be a reliable and efficient method suitable for distinguishing genetic differentiation on population level. Therefore, combination of different approaches was used in order to give comprehensive assessment of the situation. The results were consistent, revealing the levels of populations&rsquo;&nbsp; polymorphism and structure, as well as certain variations of morpho-anatomical features.</p><p>This is important in the light of complicated&nbsp; taxonomy clarification, and on the other hand from the aspect of potential value or harm of these plants to humans. In terms of&nbsp; biodiversity conservation, insight into population variability levels might contribute to adequate management strategies for both plants and insects related to them.</p>

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第21614号 / 理博第4521号 / 新制||理||1649(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 村山 美穂, 教授 幸島 司郎, 教授 平田 聡 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

La polyploïdie est un processus important et un moteur de la diversification et de l'évolution des plantes. Peu de polyploïdes naturels ont été décrits chez Juniperus, un genre de conifère représenté par 75 espèces d'arbres ou arbustes à feuilles persistantes, largement réparties dans l'hémisphère nord. Dans ce travail de recherche, l’implication de la polyploïdie dans l'évolution de Juniperus et l’élucidation des mécanismes sous-jacents à ces événements de polyploïdisation sont explorées. La taille du génome (TG) et le niveau de ploïdie ont été évalués chez 111/115 taxons en utilisant la cytométrie en flux et les comptages chromosomiques. Le taux de polyploïdie chez les genévriers s’est avéré être exceptionnellement élevé : 15 taxons sont des tétraploïdes et un seul taxon (J. foetidissima) est hexaploïde. Juniperus foetidissima représente le seul conifère hexaploïde découvert à ce jour à part Sequoia sempervirens. Nous avons également utilisé des approches de modélisation phylogénétique pour déterminer la TG ancestrale dans les trois clades de Juniperus et pour reconstruire le processus évolutif de la polyploïdisation chez ce genre. Au moins 10 événements de polyploïdisation ont eu lieu au cours de l'évolution et de la diversification de Juniperus. Nous avons ensuite exploré l’origine de la polyploïdie chez certaines espèces méditerranéennes. La variation de la TG et le niveau de ploïdie de deux variétés de J. sabina ont été estimés : Les populations échantillonnées de J. sabina var. sabina se sont avérées être diploïdes, tandis que les populations de J. sabina var. balkanensis étaient toutes tétraploïdes. Ces derniers auraient été issus d'une ancienne hybridation entre le tétraploïde J. thurifera et le diploïde J. sabina. Dans les Alpes françaises, où J. sabina var. sabina et J. thurifera sont en sympatrie, des individus présentant des morphologies intermédiaires entre ces deux espèces sont observés. Suite à des estimations des TG, de séquençage des ITS et de régions chloroplastiques, ces individus sont considérés comme des hybrides triploïdes. Enfin, l’utilisation des marqueurs AFLP pour déchiffrer les relations phylogénétiques entre des espèces méditerranéenne a montré que plusieurs pools génétiques contribuent à la diversité de Juniperus. Aussi ces marqueurs ont contribué à la découverte des contributions de ces pools génétiques aux taxons polyploïdes. Alors que les populations libanaises de l'hexaploïde J. foetidissima sont issues d'une lignée ancestrale unique, la population grecque semble résulter d'un mélange inégal de deux lignées anciennes. Ces deux lignées contribuent également au tétraploïde J. thurifera. Cette analyse a également montré que l’espèce méditerranéenne J. excelsa et l’espèce africaine J. procera partagent la même lignée ancestrale. Cependant, des analyses supplémentaires sont nécessaires pour une interprétation plus complète des données. L'importance de l'hybridation interspécifique et de la polyploïdie dans l'évolution des espèces de Juniperus nécessite d’amples recherches visant à comprendre le lien entre ces mécanismes et l'adaptation de ces espèces à un large spectre d'habitats extrêmes. Ces recherches futures devraient aussi contribuer à découvrir comment les espèces de conifères peuvent s’adapter aux changements climatiques. / Polyploidy is considered as an important phenomenon and a key driving force for plant diversification and evolution. Few natural polyploid species have been described in Juniperus, a coniferous genus represented by 75 species of evergreen trees or shrubs widely distributed in the North Hemisphere. The occurrence of polyploidy in the evolution of this genus as well as a more comprehensive view of pathways that were involved in these polyploidization events are explored in this research work. Genome size (GS) and ploidy level assessments were conducted on 111/115 taxa using flow-cytometry and chromosome counts. Juniperus holds an exceptionally high rate of polyploidy, 15 taxa being tetraploids and just one (J. foetidissima) being hexaploid. It represents the only hexaploid conifer discovered to date after Sequoia sempervirens. We also used phylogenetically-informed trait evolution modelling approaches to determine ancestral GS in the three clades of Juniperus and to reconstruct the evolutionary process of polyploidization in Juniperus. At least 10 polyploidization events have occurred during Juniperus evolution and diversification. We then explored the origin of polyploidy in selected Mediterranean species. The GS variation and the ploidy level of two J. sabina varieties were estimated: J. sabina var. sabina sampled populations were shown to be diploid, while J. sabina var. balkanensis populations were all tetraploid. The latter has been postulated to have arisen from an ancient hybridization between the tetraploid J. thurifera and the diploid J. sabina. In the French Alps, where J. sabina var. sabina and J. thurifera occur in sympatry, individuals with intermediate morphologies between these two species are observed. Evidences based on GS assessments, ITS and chloroplastic sequences demonstrated these individuals as triploid hybrids. Finally, the use of AFLP markers to decipher phylogenetic relationships between Mediterranean and Eastern Mediterranean species showed that multiple lineages contributes to Juniperus diversity and shed light on some polyploid taxa origins. While the Lebanese populations of the hexaploid J. foetidissima are issued from a unique ancestral lineage, the Greek population seems to be the result of an unequal admixture of two ancient lineages. These two lineages contribute also to the tetraploid J. thurifera. This analysis showed also that the Mediteranean J. excelsa and the African taxa J. procera shares the same ancestral lineage. However, further analyses are needed for a more complete interpretation of the data. The importance of interspecific hybridization and of polyploidization in the evolution of Juniperus species argues in favor of the development of researches aiming at understanding the link between these mechanisms and the adaptation of those species to a wide range of extreme habitats. Such future researches should contribute to predict how conifer species may adapt to dramatic changes in the Earth’s climate.

Las plantas acuáticas del género Ruppia habitan lagunas costeras, salinas, humedales y aguas salinas interiores, jugando un papel ecológico clave. Estos sistemas se caracterizan por variaciones extremas de las condiciones ambientales tales como salinidad, temperatura e inundación. La compleja historia evolutiva del género Ruppia ha dificultado la delimitación de especies en el género. Estas especies han desarrollado una gran diversidad de estrategias biológicas para sobrevivir en estos ambientes extremos, tales como ciclos de vida anuales y perennes, reproducción sexual y propagación vegetativa, estrategias de polinización epihidrófila e hidroautogámica, así como autofecundación y fecundación cruzada. Además, existen diferentes vectores que pueden facilitar el flujo de genes entre las poblaciones, incluyendo corrientes marinas, aves acuáticas y peces. Estas características biológicas de Ruppia tienen una influencia importante en sus patrones de especiación, diversidad genotípica y genética, y su estructura poblacional. Por lo tanto, los análisis genéticos proporcionan información importante para delimitar especies y taxones dentro de este género, evaluar la diversidad e identificar procesos y flujos que actúan a distintas escalas temporales y espaciales. Los objetivos principales de esta tesis son: inferir los procesos evolutivos y biológicos de especiación y diversificación, y evaluar la prevalencia y estructura poblacional de especies Europeas del género Ruppia. Esta tesis se centra principalmente en las zonas costeras de la Península Ibérica, debido a la alta diversidad de especies de Ruppia registradas en esta zona geográfica, y al hecho de que en muchas ocasiones es posible encontrar poblaciones de diferentes especies en simpatría. Para alcanzar estos objetivos, en el Capítulo I, se desarrollaron y validaron diez nuevos marcadores moleculares polimórficos (es decir, microsatélites) para Ruppia cirrhosa. Adicionalmente se obtuvo amplificación cruzada con otros dos microsatélites descritos anteriormente para R. maritima. Estas herramientas moleculares son importantes para el estudio de plantas clonales y se han utilizado junto con secuencias nucleares y del cloroplasto en los siguientes capítulos. En el Capítulo II, se estudió la sistemática del género Ruppia en Iberia considerando criterios morfológicos, marcadores nucleares altamente variables (microsatélites) y secuencias nucleares (ITS) y del cloroplasto (psbA-trnH). Al realizar la filogenia utilizando marcadores con diferentes tiempos de mutación y mecanismos hereditarios, pudo identificarse el importante papel de la hibridación y la introgresión en la historia evolutiva de este género. De las tres especies tradicionalmente descritas en la Península Ibérica, se observó que R. drepanensis y R. cirrhosa se situaron en el mismo clado filogenético tanto para los marcadores nucleares como para los cloroplastos, por lo que pueden considerarse especies hermanas. R. maritima está incluida en un clado más distante filogenéticamente, apoyado por ambos marcadores. Además, dos nuevas entidades genéticas fueron identificadas, R. cf. maritima y "R. híbrido", las cuales mostraron algunas incongruencias entre los árboles filogenéticos del núcleo y del cloroplasto, así como una combinación de alelos de microsatélites que sugieren la existencia de efectos de hibridación y/o introgresión. En el Capítulo III, mediante el estudio de microsatélites en diferentes poblaciones de R. cirrhosa de la Península Ibérica y Sicilia, se detectó una fuerte estructura genética poblacional. En términos generales, se registró un bajo nivel de flujo génico, el cual fue más importante entre poblaciones geográficamente cercanas o ubicadas en el mismo cuerpo hidrológico. Además, se evaluaron diferentes hipótesis para explicar la conectividad entre las poblaciones a través de correlaciones entre distancias geográficas y genéticas, sugiriendo que el vector de dispersión más probable entre las poblaciones de R. cirrhosa en la Península Ibérica son las aves acuáticas. Al compilar los resultados del Capítulo II y el Capítulo III, se evaluaron los efectos de diferentes estrategias reproductivas sobre la diversidad genotípica y genética de Ruppia. Todas las entidades genéticas mostraron elevadas tasas de reproducción sexual. En R. cirrhosa, los mayores índices de reproducción sexual se detectaron en los hábitats más inestables hidrológicamente. Estas perturbaciones podrían promover la germinación y el establecimiento de semillas por una baja competencia interespecífica por el espacio, la luz y otros recursos existentes en praderas menos densas. Los mayores valores de diversidad genética detectados en los epihidrófilos R. drepanensis, R. cirrhosa y probablemente en “R. híbrido” (ésto no se ha confirmado) que en la hidroautogámica Ruppia cf. maritima, sugieren una fuerte influencia del modelo de polinización sobre los patrones de diversidad genética. En el Capítulo IV, R. maritima fue identificada por primera vez en Cabo Verde (Isla de Santiago) a partir de análisis morfológicos y filogenéticos. Esta información amplía la distribución geográfica de esta especie al África Occidental.

A thesis submitted to the school of graduate studies in the partial fulfillment of the requirements for the degree doctor of philosophy. / Fungal populations occupy a vast number of ecological niches across many geographic areas around the planet. Fungi act as essential nutrient recyclers, playing key roles as saprophytes, mutualists, and pathogens. As humans, we use these broad properties of fungi in biochemical and pharmaceutical industries, creating a plethora of products ranging from antimicrobials to food products. However, certain fungal species have become a devastating burden on human public health. Of these fungal species, my PhD thesis has focused on the critically important mold Aspergillus fumigatus. This mold is an opportunistic human pathogen, being the leading etiological cause of the spectrum of diseases termed aspergillosis that yearly affects over 8,000,000 people worldwide. In addition, the rising number of antifungal resistant strains around the world, especially within environmental populations, is of critical concern. Given that almost all aspergillosis infections result from environmental strains, and that soil is a major ecological niche for A. fumigatus, my thesis focused on characterizing genetic and phenotypic aspects of soil isolates of A. fumigatus obtained from many geographic and climatic regions around the world. My analyses revealed extensive allelic and genotypic diversity within and among populations. These A. fumigatus populations were defined by both historical differentiations, high gene flow, non-random recombination, and high susceptibility to triazole antifungals. Additionally, I tested the sexual fecundity of a subset of these global strains and found that geographic and genetic distance between the pairs of parental strains had little effect on sexual fecundity. Lastly, my research found broad variations in growth of a global sample of A. fumigatus strains at different temperatures. Again, no relationship of either geographic or genetic distance on strain growth was observed. Overall, my research highlights the extraordinary nature of A. fumigatus populations to quickly spread and adapt across diverse and complex environments. / Thesis / Doctor of Philosophy (PhD) / Aspergillus fumigatus is a cosmopolitan mold that causes opportunistic infections in humans termed aspergillosis. To better understand the environmental reservoirs of aspergillosis infection, I investigated soil populations of this fungus, as soil is likely the largest reservoir of A. fumigatus. I isolated A. fumigatus strains from 11 countries across 6 continents and genetically compared these soil populations to each other and to clinical A. fumigatus populations. I found extensive genetic diversity within most local soil populations, along with different relationships among geographic populations. When a sample of these global strains were sexually crossed, I uncovered high variation in their sexual fecundity, which lowered at higher geographic distances. Lastly, strains exhibited high variations in growth at different temperatures regardless of climatic, genetic, and geographic factors from where they were isolated. My thesis highlights the extraordinary phenotypic variations and complex population structure of A. fumigatus populations isolated from soil across the globe.

Rice (Oryza sativa) is the staple food for more than 3.5 billion people worldwide. As the population continues to grow, rice yield will need to increase by 1% every year for the next 30 years to keep up with the growth. In the US, Arkansas accounts for more than 50% of rice production. Over the last 68 years, rice production has continued to grow in Mississippi, placing it in fourth place after Arkansas, Louisiana, and California. Due to increasing rice acreage, regionally and worldwide, the need to develop abiotic stress-tolerant rice has increased. Unfortunately, current rice breeding programs lack genetic diversity, and many traits have been lost through the domestication of cultivated rice. Currently, stressors stemming from the continued effects of climate change continue to impact rice. To counteract the impacts of climate change, research has shifted to evaluating wild and weedy relatives of rice to improve breeding techniques. Weedy rice (Oryza sativa ssp.) is a genetically similar, noxious weed in rice with increased competitive ability. Studies have demonstrated that weedy rice has increased genetic variability and inherent tolerance to abiotic stressors. The aims of this study were to 1) screen a weedy rice mini-germplasm for tolerance to cold, heat, and complete submergence-stress, 2) utilize simple sequence repeat (SSR) markers and single nucleotide polymorphisms to evaluate the genetic diversity of the weedy rice population, and 3) use genome-wide association (GWAS) to identify SNPs associated with candidate genes within the population.