A produção de batata no Brasil é migratória, devido à alta ocorrência de doenças de solo onde seu cultivo é realizado anualmente após a cultura do milho (Zea mays) e o preparo de solo é feito com grade aradora, implemento cujo uso freqüente estabelece impedimentos físicos. O presente trabalho avaliou um sistema de preparo profundo de solo associado ao cultivo de três diferentes gramíneas Panicum maximum cv. Tanzânia, Brachiaria brizantha cv. Marandu e milho híbrido Dekalb 191 quanto a sua capacidade de promover melhores condições físicas de solo, assim como sua influência sobre a produtividade e ocorrência de doenças na cultura da batata. O preparo de solo alternativo foi capaz de promover melhores condições físicas de solo e, mesmo após dois ciclos da sucessão de culturas, não houve influência da espécie de gramínea utilizada sobre os parâmetros avaliados, embora essas plantas tenham apresentado características diferentes quanto à produção de raízes e de parte aérea. As melhores condições físicas de solo foram responsáveis pelo aumento da produtividade e da qualidade de tubérculos, obtido com o preparo profundo de solo, mas não influenciou a ocorrência de doenças e de outros danos aos tubérculos. A incidência de doenças em geral foi baixa e isso indica que um trabalho com maior número de ciclos da sucessão de culturas seria necessário para testar a hipótese de que o sistema de preparo de solo e sucessão de culturas avaliado descartaria a necessidade de migração na cultura da batata. / Potato crop migrates continually in Brazil, due to the high incidence of soil diseases where potato is cultivated every year after a maize (Zea mays) crop cycle and when chisel plough, which causes sub-superficial compaction, is used for soil management. This work evaluated a soil deep tillage system associated to three different grasses, Panicum maximum cv. Tanzânia, Brachiaria brizantha cv. Marandu and maize Dekalb 191 in order to improve soil physical conditions and to reduce potato soil diseases incidence. The soil deep tillage system improved soil physical conditions and, although the evaluated grasses presented different characteristics of root and shoot production, the grass specie did not influence the evaluated soil parameters and potato productivity after two years of research. The soil physical improvement promoted higher potato yield and quality in the soil deep tillage system but did not influence diseases incidence and other damages to the tubers, assessed after harvesting. The average disease incidence was low, which meant a longer term work was necessary to show if the soil deep tillage system associated to grasses would avoid the Brazilian potato crop migration.

A ocorrência das doenças de final de ciclo causadas pelos fungos Septoria glycines e Cercospora kikuchii é facilmente observada no campo. Entretanto, são necessárias informações precisas sobre a quantificação de danos e perdas na produtividade, bem como, a definição da melhor época para aplicação de fungicidas. A falta de um método padrão de quantificação visual pode levar a estimativas imprecisas da severidade das mesmas, induzindo a conclusões erradas. Com os objetivos de elaborar e validar uma escala diagramática para a quantificação das doenças de final de ciclo da soja, avaliar o efeito dessas doenças sobre a produtividade, identificar o melhor estádio fenológico da cultura para o controle dessas doenças, verificar a relação entre a severidade dessas doenças e a produtividade e avaliar os efeitos das mesmas sobre a duração e absorção da área foliar sadia das plantas de soja, foram instalados experimentos na Fazenda Areão (ESALQ/USP), localizada em Piracicaba - SP. Utilizou-se o cultivar de soja MG/BR - 46 (Conquista), considerado suscetível a essas doenças, adotando-se o delineamento experimental de blocos ao acaso, no esquema fatorial 2 x 3 (dois fungicidas: benomyl e tebuconazole e três momentos fenológicos de pulverização: R4, R5.3 e R6) com três tratamentos adicionais (testemunha, pulverização quinzenal de benomyl e pulverização quinzenal de tebuconazole), repetidos três vezes. Determinou-se a severidade dessas doenças; o número de vagens e de sementes por planta; a massa de 1000 sementes e a produtividade. Para quantificação da severidade dessas doenças foi elaborada uma escala diagramática a partir de folhas coletadas em campo, apresentando diferentes níveis de severidade. A área de cada folha e sua correspondente severidade foram determinadas e, seguindo-se a “Lei do Estímulo de Weber-Fechner”, elaborou-se a escala com os níveis de severidade de doença: 2,4; 15,2; 25,9; 40,5 e 66,6%. A validação foi realizada por nove avaliadores, sem experiência na avaliação das doenças de final de ciclo, os quais estimaram a severidade de 30 folíolos de soja com sintomas destas doenças. A precisão das avaliações variou de acordo com o avaliador (0,84<R 2 <0,65), bem como a acurácia (0,00<a<3,40; 0,90<b<1,29), não ocorrendo erro sistemático na superestimativa ou subestimativa da doença entre os avaliadores. Com base nos resultados obtidos em três safras agrícolas consecutivas (1999/2000, 2000/2001 e 2001/2002), pôde-se concluir que: a) a escala diagramática desenvolvida é adequada para a quantificação da severidade das doenças de final de ciclo em soja; b) as doenças de final de ciclo, quando em severidade inferior a 10%, não afetam o número de vagens e sementes produzidos por planta mas, causam redução na produtividade da soja; c) os fungicidas benomyl e tebuconazole podem ser utilizados no controle dessas doenças; d) não foi possível determinar a época fenológica mais adequada para a pulverização de fungicidas, que proporcionasse aumentos na produtividade da soja; e) em severidade dessas doenças abaixo de 10%, não existe relação entre esta variável, a massa de 1000 sementes e a produtividade; f) a absorção da área foliar sadia é a variável que melhor expressa a relação entre a severidade dessas doenças e a produtividade da soja. / The occurrence of late season leaf diseases caused by the fungus Septoria glycines and Cercospora kikuchii is easily identified in field. However, there is a need of precise information to quantify the damage and yield losses as well as to define the best occasions for fungicide applications. The lack of a standardized visual method may lead to inaccurate estimates of their severity, inducing inexact conclusions. With the purposes: to elaborate and validate a diagrammatic scale to assess late season leaf soybean diseases; to evaluate the effect of theses diseases on yield; to identify the best soybean growth stages for chemical control; to verify the relation between severity of theses diseases and yield and to evaluate the effect of theses diseases on healthy leaf area duration and healthy leaf area absorption, were installed field experiments at Fazenda Areão (ESALQ/USP), in Piracicaba - SP. The soybean cultivar MG/BR - 46 (Conquista), susceptible to both diseases was sown in a complete randomized blocks design in factorial 2 x 3 (two fungicides: benomyl and tebuconazole and three application stages: R4, R5.3 e R6) and three extra treatments (control without application, fortnightly application of benomyl and fortnightly application of tebuconazole), at three replications. The severity, the pod number per plant, the seed number per pod, the mass of 1,000 seed and yield were determined. To quantify the severity of these diseases it was elaborated a diagrammatic scale, from leaves collected in the field presenting different levels of severity. The area of each leaf and its correspondent severity were determined, and following the “Stimulus Law by Weber-Fechner” a scale was elaborated with the severity levels: 2.4, 15.2, 25.9, 40.5 and 66.6%. The validation was carried out by nine appraisers, without previous practice in assessing late season leaf diseases, who estimate the severity on 30 leaflets of soybean with disease symptoms. The evaluation precision varied according to the appraiser (0.84<R 2 <0.65), as well as the accuracy (0.00<a<3.40; 0.90<b<1.29), do not occurring systematic mistakes in the super or underestimation of the disease among the appraisers. Based on the obtained results in three consecutive crop seasons (1999/2000, 2000/2001 e 2001/2002), it was possible to conclude that: a) the developed diagrammatic scale is appropriate to quantify the late season leaf diseases severity of soybean; b) the late season leaf diseases, when in severity below 10%, do not affect the number of pod and seeds per plant but cause reduction of yield; c) the fungicides benomyl and tebuconazole may be used to control these diseases; d) it was not possible to determine the most appropriate growth stage for fungicide application, which result in yield gain; e) under severity below 10% there are not relation between this variable and the mass of 1,000 seed and yield; f) the healthy leaf area absorption is the variable which most express the relation between the severity of this diseases and the soybean yield.

O psilídeo Diaphorina citri é vetor das bactérias Candidatus Liberibacter asiaticus e Ca. L. americanus, associadas ao Huanglongbing (HLB) dos citros. Apesar da grande importância desta doença no mundo, sabe-se pouco sobre a atividade alimentar deste vetor, o que seria fundamental para entender o processo de transmissão desses patógenos e aprimorar estratégias de manejo da doença. Assim, esta pesquisa teve por objetivos: a) examinar aspectos morfológicos do aparato bucal de D. citri; b) caracterizar o seu comportamento alimentar em mudas de laranja doce (Citrus sinensis) através da técnica de Electrical Penetration Graph (EPG)-sistema DC; e c) avaliar o efeito da idade de folhas cítricas na penetração estiletar deste inseto e na eficiência de aquisição de Ca. L. asiaticus. Adultos de D. citri apresentam um rostro que se projeta logo após o par de coxas protoráxicas. Verificou-se que na extremidade distal desta estrutura há quatro pares de sensilas em simetria bilateral. O rostro abriga um feixe de quatro estiletes (2 mandíbulas e 2 maxilas) com comprimento médio de 512 µm. Os estiletes maxilares se acoplam formando os canais alimentar e salivar com diâmetros de 0,90 µm e 0,47 µm, respectivamente; esses dois canais se fundem próximo à extremidade distal de uma das maxilas para formar um canal comum, que se estende por, aproximadamente, 4,1 µm. No estudo de EPG, as formas de onda foram descritas quanto à amplitude, frequência, nível de voltagem e origem elétrica, sendo correlacionadas com atividades estiletares baseando-se em análises histológicas da posição da extremidade distal da bainha salivar no tecido vegetal e semelhanças com outras formas de onda descritas para afídeos. Cinco formas de onda foram descritas: (C) penetração intercelular no parênquima; (D) contato com o floema; (E1) salivação no floema; (E2) ingestão no floema; e (G) ingestão no xilema. Com um tempo médio de 206,1 min em 8 h de registro, a ingestão no floema (E2) é a principal atividade observada em D. citri. O tempo médio para atingir o floema desde a primeira prova é de 154 min, após 20,3 provas. D. citri mostra nítida preferência por folhas novas da porção superior da planta (71,3% dos indivíduos), e pela nervura principal na face abaxial das folhas (87,1%). Cortes histológicos revelam que folhas maduras apresentam lignificação nas paredes de células que compõem a camada de fibras, tecido que antecede o feixe floemático; já as folhas novas não apresentam esse espessamento, favorecendo o caminhamento estiletar rumo ao floema. Adultos de D. citri adquirem Ca. L. asiaticus com maior eficiência em folhas novas (assintomáticas) do que em folhas maduras (sintomáticas) de plantas infectadas. Aplicando-se a técnica de EPG, verificou-se que as folhas novas favorecem a alimentação floemática de D. citri; quase que a totalidade dos indivíduos avaliados sobre folhas novas assintomáticas encontraram o floema e permaneceram por mais tempo neste tecido, o que não foi constatado sobre folhas maduras sintomáticas. Esta pesquisa mostra que o comportamento alimentar de D. citri é influenciado pela idade das folhas cítricas, com implicações sobre a eficiência de aquisição da bactéria. / The Asian citrus psyllid, Diaphorina citri, is the vector of the phloem-limited bacteria Candidatus Liberibacter asiaticus and Ca. L. americanus, which are associated to the serious disease known as Citrus Huanglongbing (HLB). Despite the importance of this disease worldwide, little is known about the feeding activities of the vector, which is essential to understand transmission mechanisms and establish disease management strategies. Thus, the goals of this research were to examine the morphology of D. citri mouth apparatus, to characterize its probing behavior on sweet orange (Citrus sinensis) seedlings by using the Electrical Penetration Graph (EPG)-DC technique, and to assess the effect of citrus leaf age on the stylet penetration and efficiency of acquisition of Ca. L. asiaticus. D. citri shows a coneshaped rostrum that extends itself to behind the prothoracic pair of thighs. By electron microscopy, we found four pairs of sensilla symmetrically distributed on the distal end of the rostrum. The rostrum houses a stylet bundle comprised of two mandibulae and two maxillae with mean length of 512 µm. The two maxillary stylets are hold together and have internal grooves that form the food and salivary duct, with mean diameters of 0.9 and 0.47 µm, respectively. These two canals merge at a distance of 4.1 µm from the distal tip of the stylets, forming a common duct. In the EPG study, waveforms were described according to characteristics of amplitude, frequency, voltage level and electrical origin, and correlated with stylet activities based on histological analysis of salivary sheath termini in the plant tissue and similarities with EPG waveforms previously described for aphids. Five distinct waveform types were described: (C) intercellular stylet pathway through parenchyma, (D) phloem contact, (E1) salivation in the phloem sieve tubes, (E2) phloem sap ingestion, and (G) in xylem sap ingestion. Phloem sap ingestion (E2) is the main activity observed for D. citri, with an average time of 206.1 min in 8 h of recordings. Mean time to reach sieve tubes from the first probe is 154 min, after 20.3 probes. This insect shows a clear preference for young leaves of the upper portion of the plant (71.3% of the individuals), and main vein on the abaxial leaf surface (87.1%). Mature leaves show lignification in cell walls of the fiber layer adjacent to the phloem. In contrast, young leaves do not show cell wall thickening in this fiber layer, favoring stylet pathway towards the phloem. Adults of D. citri acquired L. Ca asiaticus with greater efficiency on young (asymptomatic) leaves than in mature (symptomatic) leaves from infected plants. Applying the EPG technique, it was found that young asymptomatic leaves favor phloem feeding by D. citri, since most individuals reached phloem sieve tubes and remained longer in this tissue; this was not the case for individuals confined on mature symptomatic leaves. This study shows that feeding behavior of D. citri is influenced by citrus leaf age, with implication on efficiency of bacterial acquisition from infected plants.

Dentre os diversos fatores que afetam a produção e qualidade de frutos em plantas cítricas, os fatores fitossanitários destacam-se pela grande importância. Entre as diversas doenças que afetam a cultura dos citros, a Clorose Variegada dos Citros (CVC) é uma das mais severas e destrutivas, provocando tanto perdas em produção quanto em qualidade. Pelo fato desta doença ser causada por uma bactéria que se aloja no xilema, toda a dinâmica da água e nutrientes é afetada, resultando em uma série de sintomas visuais em diferentes graus. Buscou-se avaliar o estado nutricional de plantas cítricas sem sintomas vis uais de CVC e, com sintomas em diferentes níveis, através do Critério de Faixas de Suficiência, tradicionalmente utilizado na Citricultura Paulista e, através do Sistema Integrado de Diagnose e Recomendação, denominado pela sigla DRIS. O estudo foi realizado em pomares comerciais de laranjeira 'Pera' enxertada em limão 'Cravo', com sete anos de idade, no município de Araraquara – SP. Foram selecionadas em dois talhões, plantas com três níveis de CVC e plantas sem sintomas visuais, determinando-se os teores dos macronutrientes (N, P, K, Ca, Mg, S) e dos micronutrientes (B, Cu, Fe, Mn e Zn) em folhas de ramos frutíferos, bem como produção de frutos de cada planta. A interpretação através do método DRIS, envolveu a utilização de um "software" aplicado especialmente para a cultura dos citros pelo Instituto Agronômico de Campinas - IAC, onde foi utilizado o método de cálculo proposto por Jones (1981). O DRIS foi eficiente, possibilitando a ordenação dos nutrientes, e, indicando deficiência nutricional para alguns nutrientes considerados adequados ou excessivos pelo Critério de Faixas de Suficiência. Independentemente da presença de sintomas de CVC, todas as plantas apresentaram baixos teores de Ca, resultando em diagnose de deficiência pelos dois critérios de interpretação; de modo geral, houve uma redução nos teores foliares de N e P, em plantas com sintomas mais severos. Com relação aos teores dos demais nutrientes não houve um padrão de decréscimo ou aumento em função da CVC. O "software" DRIS aplicado especialmente para a cultura dos citros pelo IAC, com a população de referência por ele utilizada, deve ainda sofrer ajustes, de acordo com as condições e objetivos do trabalho para melhor correlação com produtividade. / Among all factors which affect the yield and fruit quality from citric plants, pests and diseases are of outstanding importance. There are several pests and diseases wich affect the citrus crop. The citrus variegated chlorosis (CVC) is one of the most severe and destructive diseases affecting both yield and quality. Because this disease is caused by a xylem bacteria, the water and nutrients dinamics is affected resulting in a series of visual simptons of different intensities. There objective of this work was to evaluate the nutritional status os citrus plants without visual simptons of CVC and, with different levels of simptons of this disease. The Sufficiency Range Criteria, traditionally used in the state of São Paulo and the Diagnosis and Recommendation Integrated System (DRIS) were the methods used for leaf analysis interpretation. The study was carried out in commercial orchards of 'Pêra' sweet orange budded on 'Cravo' lemom, seven years old, in the region of Araraquara – SP. Plants with three levels of CVC and plants without visual simptons were selected from two plots. Concentrations of macronutrients (N, P, K, Ca, Mg, S) and micronutrients (B, Cu, Fe, Mn, Zn) were determined on leaves of fruit branches. Fruit production from each plant was measured. The analysis through the DRIS method involved the utilization of a software developed specially for the citrus crop by the Instituto Agronômico de Campinas – IAC, where the method proposed by Jones (1981) was used. The results showed that the DRIS was efficient in ranking the nutrients and indicating the nutritional defficiency for some nutrients considered adequate or excessive by the Sufficiency Range Criteria. Regardless the presence of CVC simptons, all plants show low foliar concentrations of Ca, wich resulted in a diagnose of defficiency by the two criteria of interpretation. There was a foliar concentration reduction of N and P, in plants with more severe simptoms. With respect to the foliar concentration of the other nutrients there was not observed a standard decrease or increase due to CVC. The local DRIS-Citros IAC software norms utilized should be adjusted according to the work conditions and objectives to a improve yield correlation with plant nutrition.

Dentre os diversos fatores que afetam a produção e qualidade de frutos em plantas cítricas, os fatores fitossanitários destacam-se pela grande importância. Entre as diversas doenças que afetam a cultura dos citros, a Clorose Variegada dos Citros (CVC) é uma das mais severas e destrutivas, provocando tanto perdas em produção quanto em qualidade. Pelo fato desta doença ser causada por uma bactéria que se aloja no xilema, toda a dinâmica da água e nutrientes é afetada, resultando em uma série de sintomas visuais em diferentes graus. Buscou-se avaliar o estado nutricional de plantas cítricas sem sintomas vis uais de CVC e, com sintomas em diferentes níveis, através do Critério de Faixas de Suficiência, tradicionalmente utilizado na Citricultura Paulista e, através do Sistema Integrado de Diagnose e Recomendação, denominado pela sigla DRIS. O estudo foi realizado em pomares comerciais de laranjeira 'Pera' enxertada em limão 'Cravo', com sete anos de idade, no município de Araraquara - SP. Foram selecionadas em dois talhões, plantas com três níveis de CVC e plantas sem sintomas visuais, determinando-se os teores dos macronutrientes (N, P, K, Ca, Mg, S) e dos micronutrientes (B, Cu, Fe, Mn e Zn) em folhas de ramos frutíferos, bem como produção de frutos de cada planta. A interpretação através do método DRIS, envolveu a utilização de um "software" aplicado especialmente para a cultura dos citros pelo Instituto Agronômico de Campinas - IAC, onde foi utilizado o método de cálculo proposto por Jones (1981). O DRIS foi eficiente, possibilitando a ordenação dos nutrientes, e, indicando deficiência nutricional para alguns nutrientes considerados adequados ou excessivos pelo Critério de Faixas de Suficiência. Independentemente da presença de sintomas de CVC, todas as plantas apresentaram baixos teores de Ca, resultando em diagnose de deficiência pelos dois critérios de interpretação; de modo geral, houve uma redução nos teores foliares de N e P, em plantas com sintomas mais severos. Com relação aos teores dos demais nutrientes não houve um padrão de decréscimo ou aumento em função da CVC. O "software" DRIS aplicado especialmente para a cultura dos citros pelo IAC, com a população de referência por ele utilizada, deve ainda sofrer ajustes, de acordo com as condições e objetivos do trabalho para melhor correlação com produtividade. / Among all factors which affect the yield and fruit quality from citric plants, pests and diseases are of outstanding importance. There are several pests and diseases wich affect the citrus crop. The citrus variegated chlorosis (CVC) is one of the most severe and destructive diseases affecting both yield and quality. Because this disease is caused by a xylem bacteria, the water and nutrients dinamics is affected resulting in a series of visual simptons of different intensities. There objective of this work was to evaluate the nutritional status os citrus plants without visual simptons of CVC and, with different levels of simptons of this disease. The Sufficiency Range Criteria, traditionally used in the state of São Paulo and the Diagnosis and Recommendation Integrated System (DRIS) were the methods used for leaf analysis interpretation. The study was carried out in commercial orchards of 'Pêra' sweet orange budded on 'Cravo' lemom, seven years old, in the region of Araraquara - SP. Plants with three levels of CVC and plants without visual simptons were selected from two plots. Concentrations of macronutrients (N, P, K, Ca, Mg, S) and micronutrients (B, Cu, Fe, Mn, Zn) were determined on leaves of fruit branches. Fruit production from each plant was measured. The analysis through the DRIS method involved the utilization of a software developed specially for the citrus crop by the Instituto Agronômico de Campinas - IAC, where the method proposed by Jones (1981) was used. The results showed that the DRIS was efficient in ranking the nutrients and indicating the nutritional defficiency for some nutrients considered adequate or excessive by the Sufficiency Range Criteria. Regardless the presence of CVC simptons, all plants show low foliar concentrations of Ca, wich resulted in a diagnose of defficiency by the two criteria of interpretation. There was a foliar concentration reduction of N and P, in plants with more severe simptoms. With respect to the foliar concentration of the other nutrients there was not observed a standard decrease or increase due to CVC. The local DRIS-Citros IAC software norms utilized should be adjusted according to the work conditions and objectives to a improve yield correlation with plant nutrition.

Bibliography: leaves 207-220. Pseudomonas corrigata strain 2140 (Pc2140), isolated from wheat field soil in Australia, antagonises the take-all fungus, Gaeumannomyces graminis var. tritici (Ggt) in vitro and significantly reduces take-all symptoms on wheat in pot trials. This study investigates the mechanisms by which the biocontrol agent reduces the disease symptoms. Biochemical analysis of metabolites of P. corrugata 2140 reveal a number of compounds potentially antagonistic to Ggt and which may play a role in disease control. These include water-soluble antibiotics, siderophores, proteases, peptides and volatiles including hydrogen cyanide.

Victoria blight, caused by fungus Cochliobolus victoriae, is a disease originally described on oats and recapitulated on Arabidopsis. Victoria blight is used as a model plant disease that conforms to an inverse gene-for-gene interaction. C. victoriae virulence is dependent upon its production of victorin, a host-specific toxin that induces programmed cell death in sensitive plants. In oats, victorin sensitivity and disease susceptibility is conferred by the Vb gene, which is genetically inseparable from the Pc-2 crown rust resistance gene. In Arabidopsis, victorin sensitivity and disease susceptibility is conferred by the LOCUS ORCHESTRATING VICTORIN EFFECTS 1 (LOV1) gene which encodes a NB-LRR protein, a type of protein commonly associated with disease resistance. LOV1-mediated cell death occurs when victorin binds Thioredoxin-h5 (TRX-h5) and LOV1 appears to "guards" TRX-h5. Together, these results suggest C. victoriae causes disease by inducing a resistance response. The work presented here aimed to determine if the response mediated by LOV1 is functionally related to a resistance response. We genetically characterized the response mediated by LOV1 with virus-induced gene silencing. We determined SUPPRESSOR OF THE G2 ALLELE OF SKP1 (SGT1), a gene required for the function of many resistance genes, is required for victorin sensitivity and involved in LOV1 protein accumulation. We screened a normalized library and identified six genes that suppressed victorin-mediated cell death and cell death induced by expression of the RESISTANCE TO PERONOSPORA PARASITICA PROTEIN 8 (RPP8) resistance gene: a mitochondrial phosphate transporter, glycolate oxidase, glutamine synthetase, glyceraldehyde 3-phosphate dehydrogenase and the P- and T-protein of the glycine decarboxylase complex. Silencing the latter four also inhibited cell death induced by the expression of an autoactive form of the resistance gene PTO, and reduced PTO-mediated resistance to Pseudomonas syringae pv. tabaci. These results provide evidence that victorin-mediated cell death is functionally similar to a resistance response, further supporting the hypothesis that a resistance response is exploited by C. victoriae for pathogenesis in Victoria blight. Resistance function of LOV1 was evaluated by observing Pseudomonas syringae pv. tomato virulence upon LOV1 activation. The LOV1 response pathway in Arabidopsis was adapted to activate upon infection with Pseudomonas syringae pv. tomato expressing the type III-dependent effector protein AvrRpt2, a well-characterized protease. We developed a construct to express a beta-glucuronidase (GUS) and TRX-h5 fusion protein separated by an AvrRpt2 proteolytic cleavage site, in which GUS sterically inhibits TRX-h5 function in LOV1-mediated cell death. The fusion is cleaved upon infection by P. syringae pv. tomato expressing avrRpt2, thereby leading to TRX-h5-mediated activation of LOV1 in the presence of victorin. However, when this strain was inoculated with victorin into transgenic LOV1 trx-h5 plants expressing the GUS/TRX-h5 fusion protein, no decrease in pathogen virulence was observed. Technical shortcomings likely prevented observable LOV1 resistance function. ��� / Graduation date: 2013 / Access restricted to the OSU Community at author's request from Oct. 9, 2012 - Oct. 9, 2013

There are few methods available for the spatial-temporal analysis of polygon data. This research develops a new method for spatial-temporal analysis of moving polygons (STAMP). Using an event-based framework, polygons from neighboring time periods are related by spatial overlap and proximity. The proximity spatial relation is defined by an application specific distance threshold. STAMP is demonstrated in the spatial-temporal analysis of a wildfire burning over small spatial and temporal scales, and in the spatial-temporal analysis of mountain pine beetle (Dendroctonus ponderosae Coleoptera: Hopkins) movement patterns over large spatial and temporal scales. The mountain pine beetle analysis found that short range movement patterns of mountain pine beetles occurred at different beetle population levels. Spot proliferation occurred most when beetle presence was increasing slowly, perhaps moving into new areas for the first time. When beetle presence increased rapidly, local expansion, or spot growth, was a more common movement pattern. In the Pine Pass study area. long range dispersal markedly extended the northeast border of the mountain pine beetle range.

Bibliography: leaves 207-220. / 220 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Pseudomonas corrigata strain 2140 (Pc2140), isolated from wheat field soil in Australia, antagonises the take-all fungus, Gaeumannomyces graminis var. tritici (Ggt) in vitro and significantly reduces take-all symptoms on wheat in pot trials. This study investigates the mechanisms by which the biocontrol agent reduces the disease symptoms. Biochemical analysis of metabolites of P. corrugata 2140 reveal a number of compounds potentially antagonistic to Ggt and which may play a role in disease control. These include water-soluble antibiotics, siderophores, proteases, peptides and volatiles including hydrogen cyanide. / Thesis (Ph.D.)--University of Adelaide, Dept. of Crop Protection, 1996

[Truncated abstract] The genetics of ascochyta blight resistance was studied in five 5 x 5 half-diallel cross sets involving seven genotypes of chickpea (ICC 3996, Almaz, Lasseter, Kaniva, 24B-Isoline, IG 9337 and Kimberley Large), three accessions of Cicer reticulatum (ILWC 118, ILWC 139 and ILWC 184) and one accession of C. echinospermum (ILWC 181) under field conditions. Both F1 and F2 generations were used in the diallel analysis. Almaz, ICC 3996 and ILWC 118 were the most resistant genotypes. Estimates of genetic parameters, following Hayman's method, showed significant additive and dominant gene actions. The analysis also revealed the involvement of both major and minor genes. Susceptibility was dominant over resistance to ascochyta blight. The recessive alleles were concentrated in the two resistant chickpea parents ICC 3996 and Almaz, and one C. reticulatum genotype ILWC 118. High narrow-sense heritability (ranging from 82 to 86% for F1 generations, and 43 to 63% for F2 generations) indicates that additive gene effects were more important than non-additive gene effects in the inheritance of the trait and greater genetic gain by breeding resistant chickpea cultivars using carefully selected parental genotypes. Current simple leaf varieties are often susceptible to ascochyta blight disease whereas varieties of other leaf types range from resistant to susceptible. The inheritance of ascochyta blight resistance and different leaf types and their correlation were investigated in intraspecific progeny derived from crosses among two resistant genotypes with normal leaf type (ICC 3996 and Almaz), one susceptible simple leaf type (Kimberley Large) and one susceptible multipinnate leaf type (24 B-Isoline). ... An interspecific F2 mapping population derived from a cross between chickpea accession ICC 3996 (resistant to ascochyta blight, early flowering, and semi-erect plant growth habit) and C. reticulatum accession ILWC 184 (susceptible to ascochyta blight, ii late flowering, and prostrate plant growth habit) was used for constructing a genetic linkage map. F2 plants were cloned through stem cuttings taken at pre-flowering stage, treated with plant growth regulator powder (0.5 mg/g indole butyric acid (IBA) and 0.5 mg/g naphthalene acetic acid (NAA)) and grown in a sand + potting mix substrate. Clones were screened for ascochyta blight resistance in controlled environment conditions using a 19 scale. Three quantitative trait loci (QTLs) were found for ascochyta blight resistance in this population. Two linked QTLs, located on linkage group (LG) 4, explained 21.1% and 4.9% of the phenotypic variation. The other QTL, located on LG3, explained 22.7% of the phenotypic variation for ascochyta blight resistance. These QTLs explained almost 49% of the variation for ascochyta blight resistance. LG3 had two major QTLs for days to flowering (explaining 90.2% of phenotypic variation) and a major single QTL for plant growth habit (explaining 95.2% of phenotypic variation). There was a negative correlation between ascochyta blight resistance and days to flowering, and a positive correlation between days to flowering and plant growth habit. The flanking markers for ascochyta blight resistance or other morphological characters can be used in marker-assisted selections to facilitate breeding programs.