Magistrantūros baigiamasis darbas atliktas 2011–2013 m. Aleksandro Stulginskio universiteto Bandymų stotyje ir Agroekosistemų ir dirvožemio mokslų instituto laboratorijoje. Tyrimų objektas – žieminis rapsas (Brassica napus L.) ir jo atskirų morfologinių dalių liekanos dirvoje. Taip pat, piktžolės: baltoji balanda, dirvinė pienė, kibusis lipikas. Tyrimų tikslas – nustatyti ir įvertinti atskirų žieminių rapsų morfologinių dalių liekanų – kūlenų, ražienojų ir šaknų (po derliaus nuėmimo, dirvoje irusių tris, septynis ir keturiolika mėnesių) – vandeninių ištraukų alelopatinę įtaką piktžolių (baltosios balandos, dirvinės pienės ir kibiojo lipiko) dygimui ir augimui. Tyrimų schema – A veiksnys – rapsų liekanos: 1) žieminių rapsų kūlenos; 2) žieminių rapsų ražienojai; 3) žieminių rapsų šaknys; B veiksnys – vandeninių ištraukų koncentracijos: 1) distiliuotas vanduo; 2) 1:6250 (rapsų liekanų ir vandens santykis); 3) 1:1250; 4) 1:250; 5) 1:50; 6) 1:10. Darbo rezultatai. Vertinant žieminių rapsų liekanų morfologinių dalių ir skaidymosi trukmės įtaką piktžolių sudygimui nustatyta, kad po derliaus nuėmimo labiausiai variavo dirvinės pienės sudygimo duomenys. Skirtingose žieminių rapsų šaknų ištraukose sudygo 94–100 % mažiau dirvinės pienės sėklų, nei distiliuotame vandenyje. Po trijų mėnesių skaidymosi geriausias sudygimo procentas (76,0 %) buvo kibiojo lipiko sėklų. Visos, septynis mėnesius skaidytos, žieminių rapsų liekanų ištraukos 46–82 % slopino dirvinės pienės sudygimą lyginant su... [toliau žr. visą tekstą] / The master wokr were conducted at Experimental Station and Laboratory of Agroecosystems and Soil Science Institute of the Aleksandras Stulginskis University in 2011–2013. Research object - winter oilseed rape (Brassica napus L.) and its various morphological parts of the residues in the soil. Also, weeds: Chenopodium album L., Galium aparine L., Sonchus arvensis L. The aim of investigations was to evaluate the allelopathic effect of aqueous extracts of winter oilseed rape residues (threshing remains, stubble and roots) on Chenopodium album L., Galium aparine L., Sonchus arvensis L. germination and early growth. Treatments of the investigations: Factor A – winter oilseed rape residues: 1) threshing remains, 2) stubble, 3) roots; Factor B – concentrations of aqueous extracts: 1) distilled water, 2) 1:6250 (ratio of oilseed rape residues and water), 3) 1:1250, 4) 1:250, 5) 1:50, 6) 1:10. The results of work. Evaluation of winter oilseed rape residues morphological parts and decomposition duration on weed emergence showed that after harvesting the most variavo Sonchus arvensis L germination data. Winter oilseed rape roots extracts germinated 94-100% units less Sonchus arvensis L seeds than in distilled water. All seven months biodegradable, winter oilseed rape residues extracts 46–82% units suppressed Sonchus arvensis L germination compared with distilled water. And after fourteen months of division all winter oilseed rape residues extracts stimulated (6,5 to 43%) Sonchus... [to full text]

The number of pods per plant and the number of seeds per pod are the most variable yield components in winter oilseed rape (WOSR). The production of a seed is the combination of several physiological processes, namely formation of ovules and pollen grains, fertilization of the ovules and development of young embryos, any problem in these processes may result in seed abortion or pod abortion. Both the number of ovules per pod and the potential for the ovule to develop into a mature seed may depend on pod position in the plant architecture and time of appearance. The complex developmental pattern of WOSR makes it difficult to analyse.In this study, we first investigate the variability of the following yield components (a) ovules/pod, (b) seeds/pod, and (c) pods/axis in relation to two explanatory variables. These two variables include (1) flower and inflorescence position and (2) time of pod appearance, linked to the effect of assimilate availability. Based on the biological phenomena of flower fertility, we developed a probabilistic model to simulate the number of ovules per ovary and seeds per pod. The model can predict the number of pollen grains per flower and distinguish the factors that influence the yield. Field experiments were conducted in 2008 and 2009. The number and position of flowers that bloomed within the inflorescence were recorded based on observations every two to three days throughout the flowering season. Different trophic states were created by clipping the main stem or ramifications to investigate the effect of assimilate competition.The results indicate that the amount of available assimilates was the primary determinant of pod and seed production. The distribution of resources was significantly affected by both the positions of pods within an inflorescence and the position of inflorescences within a plant in WOSR. In addition, model estimation for distribution parameter of pollen grain number indicated that pollination limitation could influence the seed production. Furthermore, the ovule viability could result in the decrease of the number of pods and the number of seeds per pod at the distal position of inflorescence. The model of flower fertility could be a tool to study the strategy of improving seed yield in flowering plants

No description available.

Research objective. The study was aimed to identify the dynamics of accumulation of phenolic compounds and glucosinolates in oilseed rape and the effect of different morphological parts of oilseed rape on agricultural plants and weeds. The goals of the studies. The following goals were set in order to reach the aim of the studies: 1. To identify the dynamics of accumulation of phenolic compounds in oilseed rapeduring vegetation. 2. To analyse composition of allelochemical compounds of different morphological parts of rape residues after harvesting and ascertain quantitative and qualitative changes of these compounds in rape residues that decomposed in the soil for a different period. 3. To ascertain the effect of different morphological parts of oilseed rape that remain immediately after harvesting on the germination, shoot height and root length of agricultural plants and weeds. 4. To ascertain the effect of different morphological parts of oilseed rape that decomposed in the soil for a different period on the germination, growth of shoots and roots of agricultural plants and weeds. / Tyrimų tikslas. Nustatyti fenolinių junginių ir gliukozinolatų kaupimosi rapsuose dinamiką bei rapsų skirtingų morfologinių dalių liekanų poveikį žemės ūkio augalams ir piktžolėms. Tyrimų uždaviniai: 1. Nustatyti fenolinių junginių kaupimosi dinamiką rapsuose vegetacijos metu. 2. Ištirti alelocheminių junginių sudėtį rapsų skirtingų morfologinių dalių liekanose po derliaus nuėmimo ir nustatyti jų kiekybinius ir kokybinius pokyčius skirtingą laiką dirvoje irusiose rapsų liekanose. 3. Nustatyti rapsų atskirų morfologinių dalių, liekančių iškart po derliaus nuėmimo, poveikį žemes ūkio augalų ir piktžolių sėklų dygimui, daigų aukščiui ir šaknų ilgiui. 4. Nustatyti skirtingą laiką dirvoje irusių rapsų morfologinių dalių poveikį žemės ūkio augalų ir piktžolių sėklų dygimui, daigų bei šaknų augimui.

The aim of this thesis was to compare the activity and quality of work of the combine harvester New Holland CR 9080 and John Deere 9880 STS at harvest of cereals and oilseed rape and their simple economic evaluation. The thesis was focused on comparing losses and influence of moisture of harvested crops on the size of the losses, on the quality of crushing and the spreading of plant residues. Then the inf luence of moisture of harvested crops on the quality of crushing and the spreading of plant residues, analysis of performance and consumption of diesel were compared.

Le nombre de siliques par plante et le nombre de graines par silique sont les composantes du rendement du colza d'hiver qui présentent la plus grande variabilité. La production d'une graine résulte de la combinaison de plusieurs processus physiologiques, à savoir la formation des ovules et des grains de pollen, la fécondation des ovules et le développement de jeunes embryons. Un problème survenu à n’importe quelles des étapes peut entraîner l’avortement de graines ou de la silique. Le nombre potentiel d'ovules par silique et le nombre graines arrivant la maturité dépendraient de la position du dans l'architecture de plante et le temps de son apparition, mais le mode complexe de développement de colza rend difficile l’analyse des causes et effets.Dans cette étude, la variabilité des composantes du rendement suivantes est étudiée: (a) nombre d’ovules par silique, (b) nombre de graines par silique, et (c) nombre de siliques par axe en fonction d’une part, l’emplacement de la fleur dans l'inflorescence, et la position de cette dernière sur la tige, et l’autre part, le temps d'apparition de la silique, qui affectent la disponibilité d'assimilats. Basé sur les processus biologiques de la fertilité des fleurs, un modèle probabiliste est développé pour simuler le développement des graines. Le nombre de grains de pollen par fleur peut être déduit par le modèle et ainsi que les facteurs qui influent le rendement.Des expériences de terrain ont été menées en 2008 et 2009. Le nombre et la position des fleurs qui s'épanouissaient dans l'inflorescence ont été enregistrés sur la base des observations tous les deux à trois jours pendant la saison de floraison. Différents états trophiques ont été créés par tailler de la tige principale ou des ramifications à étudier l'effet de l'assimilation de la compétition.Les résultats montrent que la quantité d’assimilâtes disponibles a été le principal déterminant de la production de graines et de siliques. La répartition d’assimilâtes a été sensiblement affectée par l’emplacement de silique au sein d’une inflorescence et la location de l’inflorescence sur la tige colza. En outre, le paramètre de la distribution du nombre de pollen a indiqué que la production de graines pourrait être limitée par la pollinisation. La réduction de la viabilité des ovules pourrait entraîner la diminution du nombre de siliques et le nombre de graines par silique à l’extrémité de l'inflorescence. Le modèle proposé pourrait être un outil pour étudier la stratégie de l'amélioration du rendement des plantes à fleurs / The number of pods per plant and the number of seeds per pod are the most variable yield components in winter oilseed rape (WOSR). The production of a seed is the combination of several physiological processes, namely formation of ovules and pollen grains, fertilization of the ovules and development of young embryos, any problem in these processes may result in seed abortion or pod abortion. Both the number of ovules per pod and the potential for the ovule to develop into a mature seed may depend on pod position in the plant architecture and time of appearance. The complex developmental pattern of WOSR makes it difficult to analyse.In this study, we first investigate the variability of the following yield components (a) ovules/pod, (b) seeds/pod, and (c) pods/axis in relation to two explanatory variables. These two variables include (1) flower and inflorescence position and (2) time of pod appearance, linked to the effect of assimilate availability. Based on the biological phenomena of flower fertility, we developed a probabilistic model to simulate the number of ovules per ovary and seeds per pod. The model can predict the number of pollen grains per flower and distinguish the factors that influence the yield. Field experiments were conducted in 2008 and 2009. The number and position of flowers that bloomed within the inflorescence were recorded based on observations every two to three days throughout the flowering season. Different trophic states were created by clipping the main stem or ramifications to investigate the effect of assimilate competition.The results indicate that the amount of available assimilates was the primary determinant of pod and seed production. The distribution of resources was significantly affected by both the positions of pods within an inflorescence and the position of inflorescences within a plant in WOSR. In addition, model estimation for distribution parameter of pollen grain number indicated that pollination limitation could influence the seed production. Furthermore, the ovule viability could result in the decrease of the number of pods and the number of seeds per pod at the distal position of inflorescence. The model of flower fertility could be a tool to study the strategy of improving seed yield in flowering plants

No description available.

Leptosphaeria maculans and L. biglobosa co-infect winter oilseed rape plants to cause phoma stem canker disease. The sexual spores of both species are produced in pseudothecia on infected winter oilseed rape stem debris after harvest and this is the most important source of inoculum for infection of newly-emerged plants in autumn. Field experiments investigated the effects of host resistance on proportions of pathogens Leptosphaeria maculans and L. biglobosa in most leaf and stem tissues during 2011/2012, 2012/2013 and 2013/2014 growing seasons and on the pseudothecial development on crop debris on nine winter oilseed rape cultivars; cvs Adriana (Rlm4 + quantitative resistance (QR)), Bilbao (Rlm4), Capitol (Rlm1), Drakkar (no R gene against L. maculans), DK Cabernet (Rlm1 + (QR), Es-Astrid (QR), Excel (Rlm7), Roxet (Rlm7) and NK Grandia (QR). Cultivars with a combination of R-gene resistance and QR [Adriana (Rlm4 + QR), DK Cabernet (Rlm1 + QR)] or cultivars with only QR [(Es-Astrid and NK Grandia)] had more numbers of L. maculans leaf spots than other cultivars in autumn but less stem canker damage. There was greater number of L. biglobosa leaf spots on leaves of cvs Roxet and Excel with resistance gene Rlm7 than those of other cultivars and later more L. biglobosa DNA was detected in their stems than in those of other cultivars. In all cultivars in the three growing seasons, there was a greater amount of L. biglobosa DNA than L. maculans DNA in basal stem canker and upper stem lesions. The cv. Drakkar (no R gene against L. maculans) was susceptible in all three growing seasons, with a great number of L. maculans and L. biglobosa leaf spots and severe stem cankers. There were four cultivars (Adriana, Bilbao, Drakkar and NK Grandia) selected for the study of pseudothecial development under natural conditions with different times of exposure and in controlled environment conditions (20oC, continuous wetness). The fastest development was on the susceptible cv. Drakkar (no R gene against L. maculans), followed by Bilbao (Rlm4), Adriana (Rlm4 + QR) and NK Grandia (QR) for stem base cankers and upper stem lesions in controlled conditions. Results for pseudothecial development on stems of the nine winter oilseed rape cultivars that were exposed in natural conditions at Bayfordbury support the controlled environment results, with pseudothecia on stems of cultivars with a combination R-gene and QR consistently maturing later than those on other cultivars, regardless of the weather conditions in three growing seasons. Ascospores produced in pseudothecia are the primary inoculum that initiate phoma stem canker epidemics in autumn. Ascospore release was later in autumn 2011 than in autumn/winter 2012/2013 or 2013/2014 because of dry weather. The pattern of ascospore release had a peak, or maximum in autumn/winter 2011/2012 (4958 spores/m-3 on 22 Jan 2012) and several maxima in autumn/winter 2012/2013 (1307 spores/m-3 on 5 Nov 2012, 1291 spores/m-3 on 15 Nov 2012, 1306 spores/m-3 on 25 Dec 2012) and 2013/2014 (4575 spores/m-3 on 27 Oct 2013, 4619 spores/m-3 on 3 Nov 2013, 3674 spores/m-3 on 9 Nov 2013, 3521 spores/m-3 on 12 Dec 2013). Results from the qPCR showed that ascospores of L. maculans were released earlier than ascospores of L. biglobosa at Bayfordbury in the 2013/2014 growing season. There were differences in phenotype of isolates amongst ninety-five isolates of L. maculans and forty-eight isolates of L. biglobosa obtained from different sources (phoma leaf spots, upper stem lesions or basal stem cankers) on different cultivars. Cotyledon tests showed that the resistance genes Rlm4, Rlm5, Rlm6 and Rlm7 are still effective in England. Most isolates from phoma leaf spots carried avirulent AvrLm4 (39 isolates; 97.5%), AvrLm5 (39 isolates; 97.5%) and AvrLm6 alleles (36 isolates; 90%) and all 40 isolates carried the avirulent allele AvrLm7 (100%). Fewer isolates from basal stem cankers carried avirulent AvrLm4 (4 isolates, 16.7%) or AvrLm6 alleles (16.7%) but all 24 isolates carried the avirulent AvrLm7 (100%). Fewer isolates from upper stem lesions carried the avirulent AvrLm4 allele (5 isolates; 16.1%), but 15 isolates carried avirulent AvrLm5 (48.4%), 21 isolates carried AvrLm6 (67.7%) and all 31 isolates carried AvrLm7 (100%). By contrast, all isolates were virulent against Rlm1, Rlm2, Rlm3 and Rlm9. This knowledge, together with knowledge about R genes present in current winter oilseed rape cultivars, should be useful to provide recommendations on cultivar selection to growers based on regional frequencies of avirulent alleles of Avr allele genes in the L. maculans populations (races) and improved understanding of the race structure of L. maculans. There is a need to further investigate any R genes that operate against L. biglobosa (possibly from wild brassicas) and to study if any R genes or QR can provide resistance against both L. maculans and L. biglobosa.

Darbo objektas – skirtingu laiku sėti žieminių rapsų (Brassica napus L. spp. oleifera bennis. Metzg.) linijinės veislės ‛Cult’ ir hibridinės – ‛Kronos’ pasėliai. Darbo metodai: Tyrimai atlikti Aleksandro Stulginskio universiteto bandymų stotyje. Vertinami biometriniai rodikliai (antžeminės dalies masė, šaknies kaklelio diametras, lapų skaičius ir viršūninio pumpuro aukštis), peržiemojimas, produktyvumo formavimasis vertinamas pagal derlingumo elementų kiekybinius ir kokybinius rodiklius, kurie priklauso nuo sėjos laiko ir peržiemojimo sąlygų: derliaus struktūros elementai (1000 sėklų masė, ankštarų skaičius, sėklų skaičius ankštaroje, 1000 sėklų masė, derlingumas). Darbo rezultatai. Vėlinant sėjos laiką, ‛Cult’ ir ‛Kronos’ rapsų biometriniai rodikliai esmingai mažėjo visais tyrimo laikotarpiais. Tinkamiausią žiemojimui viršūninio pumpuro aukštį turėjo rugpjūčio 10 d. ir 20 d. sėti abiejų veislių rapsai. Labai mažus viršūninius pumpurus turėjo rapsai pasėti rugpjūčio 30 d. ir rugsėjo 10 d. Geriausiai peržiemojo hibridiniai rapsai ‛Kronos’. Daugiausiai ankštarų taip pat užaugino hibridiniai rapsai, sėti rugpjūčio 10 d., tačiau suvėlinus sėja ankštarų daugiau formavo linijinės veislės rapsai. ‛Cult’ ir ‛Kronos’ žieminiai rapsai suvėlinus sėją užmezgė esmingai vidutiniškai 10,5 proc. mažiau sėklų ankštaroje, bet jų 1000 sėklų masė buvo didesnė. Didžiausią 1000 sėklų masę užaugino abiejų veislių rapsai sėti rugpjūčio 30 d. (‛Cult’ 5,43 g, ‛Kronos’ 5,58 g), tačiau nei sėjos laikas... [toliau žr. visą tekstą] / The object – arable crops of winter oilseed rape linear variety‛Cult’ and the hybrid ‛Kronos’ (Brassica napus L. ssp . Oleifera Bennis . Metzq) sown at different time. Methods of work: Research has been carried out in Aleksandras Stulginskis university Experimental Station. Biometric indicators ( terrestrial mass , root collar diameter , number of leaves and apical bud height) and wintering have been valued ; formation of productivity has been measured by the harvest elements of quantitative and qualitative indicators, which depend on the time of sowing and wintering conditions: structural harvest elements ( 1000 seed weight , pod number , seeds per pod , 1000 seed weight , yield ). Results. Having delayed the sowing time, ‛Cult’ and ‛Kronos’ rape biometric indicators substantially decreased in all study periods. The most appropriate for wintering apical bud height of both varieties of rape was on August 10th and 20th. Rape sown on August 30th and September 10th had a very small apical bud. The best overwintered variety of winter rape was hybrid ‛Kronos’. Hybrid rape sown on August 10th brought up the most pods, however delayed sowing time brought up more pod in linear rape. ‛Cult’ and ‛Kronos’ winter oilseed rape after delayed sowing established essentially an average of 10.5 percent less seeds in the pod, but their 1000 seed weight was greater. The largest mass of 1000 seeds originated from both varieties of oilseed rape sown on August 30th (‛Cult’ 5.43 g, ‛Kronos’ 5... [to full text]

Leptosphaeria maculans, agent de la nécrose du collet des crucifères, est un agent pathogène majeur du colza (Brassica napus). La lutte génétique est aujourd’hui le procédé le plus utilisé afin de protéger les cultures des attaques de ce champignon. Cette méthode se base principalement sur l’utilisation de cultivars possédant des gènes de résistance spécifique (Rlm) qui permettent le déclenchement des réactions de défense de la plante parla reconnaissance directe ou indirecte des produits des gènes d’avirulence correspondants (AvrLm) présents dans la population pathogène. Plusieurs de ces résistances ont déjà été massivement déployées en France et dans le monde, connaissant dans un premier temps un fort succès commercial grâce à la protection fournie, suivie d’une perte d’efficacité très rapide. Avant cette thèse, le nombre d’études au champ des processus impliqués dans le contournement d’un gène de résistance était très limité, en particulier chez les champignons. L’objectif de cette thèse était d'étudier l’évolution moléculaire du gène d’avirulence AvrLm4-7sous pression de sélection, en profitant de son clonage et de la commercialisation récente de cultivars Rlm7, afin d’obtenir une étude précoce et détaillée des mécanismes moléculaires à l’origine du contournement d’une résistance spécifique. Le gène AvrLm4-7 présente l’originalité de coder pour une protéine responsable d’une double spécificité d’interaction vis-à-vis des gènes Rlm4 et Rlm7. Dans un premier temps, j’ai pu valider par mutagenèse dirigée le rôle primordial de l’acide aminé 120 dont la mutation affecte la reconnaissance d’AvrLm4 par Rlm4 sans toutefois altérer la reconnaissance d’AvrLm7 par Rlm7.Le contournement de la résistance Rlm7 a été ensuite analysé à l’aide d’une importante collection de souches prélevée sur deux sites expérimentaux indépendants (Grignon ; Versailles) sur une période de trois ans. Sur le premier site était cultivée une variété Rlm7 en monoculture avec un travail du sol simplifié tandis que sur le second site, le mode de culture incluait rotation culturale et enfouissement par labour des résidus de cultures. Il a ensuite été montré que, au contraire de la reconnaissance AvrLm4/Rlm4, un grand nombre d’évènements de mutation peuvent être à l’origine de la virulence d’une souche vis-à-vis de Rlm7. L’analyse moléculaire des souches virulentes et avirulentes de cette collection a ainsi permis de répertorier sept catégories d’évènements de mutation. La grande majorité des cas concerne la délétion d’AvrLm4-7 mais des mutations dues au RIP et plusieurs autres évènements de mutation provoquant l’introduction prématurée de codons stop dans la séquence codante du gène sont aussi observés. La majorité de ces évènements de mutation sont liés à la reproduction sexuée du champignon et ont lieu au sein même de la parcelle d’étude. Le phénotypage de cette collection a par ailleurs révélé un fort contraste entre les deux sites expérimentaux, démontrant ainsi l’importance des pratiques culturales dans le maintien de l’efficacité de la résistance Rlm7 dans le temps. En effet, après trois années de culture de cultivars Rlm7, la fréquence des souches virulentes a7 dans les populations du site de Versailles reste inférieure à 1 % contre environ 30 % sur le site de Grignon. Finalement, le phénotypage de la collection de souches a également montré que le contournement de Rlm7 s’accompagnait dans plus de 98% des souches de la résurgence de l’avirulence AvrLm3. Par l’étude de cette collection et par croisements génétiques, j’ai pu montrer que AvrLm3 n’était pas un nouvel allèle d’avrLm4-7 mais un second gène situé en région télomérique à 19.3 cM d’AvrLm4-7. J’ai également démontré une interaction fonctionnelle antagoniste entre AvrLm4-7 et AvrLm3 qui empêche la reconnaissance Rlm3 /AvrLm3 en présence d’AvrLm4-7 et explique la restauration de l’avirulence AvrLm3 lors de la perte de l’avirulence AvrLm7.Par une association originale de biologie moléculaire, de génétique des populations et d’agronomie, j’ai ainsi pu apporter une nouvelle illustration à la course aux armements entre un agent pathogène et sa plante hôte, les gènes AvrLm3 et AvrLm4-7 utilisant deux stratégies distinctes afin d’échapper à la reconnaissance de leurs gènes de résistance spécifiques. / Leptosphaeria maculans is a filamentous ascomycete causing stem canker of oilseed rape (Brassica napus). This disease is often controlled by the use of B. napus cultivars harbouring major resistance genes (Rlm). Direct or indirect recognition of the corresponding avirulence protein (AvrLm) in the pathogen triggers plant defence reactions. Several resistances have been massively deployed in France and worldwide, they initially showed commercial success due to the protection provided and in a second time, a very fast decrease of efficiency (resistance breakdown).Prior to this thesis, field studies of resistance gene breakdown mechanisms were rare, especially for fungi. The purpose of this PhD thesis was to study the molecular evolution of the avirulence gene AvrLm4-7 under selection pressure, by exploiting our knowledge of the gene, and the recent release of Rlm7 cultivars, to obtain an early and detailed study of the molecular mechanisms involved in a resistance gene breakdown. AvrLm4-7 induces resistance responses in plant harbouring either Rlm4 or Rlm7 and I validated by targeted point mutagenesis the central role of the amino acid 120 in the avrLm4-7-Rlm4 interaction. Its mutation prevents AvrLm4-7 recognition by Rlm4 without affecting avrLm4-7-Rlm7 recognition.Loss of avirulence towards Rlm7 was then studied by the analysis of an important isolate collection originating from two independent French experimental fields (Grignon; Versailles) over three years. In the first field was cropped Rlm7 cultivars in monoculture with low tillage agronomical practices whereas crop rotation and ploughing were done in the second field. In contrast to AvrLm4-Rlm4 evolution, a great number of mutations were found to explain the “gain” of virulence towards Rlm7. Seven mutational event categories were found. The great majority of these categories involve AvrLm4-7 deletion but mutation due to RIP and several other mutational events causing premature apparition of stop codons in the coding sequence of the gene were observed too. The majority of these events are linked to the sexual reproduction of the fungus and occurs in the experimental field.In addition, our work showed the importance of the cultural practices in preserving Rlm7 efficacy. Indeed, after three years using Rlm7 cultivars, a7 frequency was below 1% whereas representing around 30% of the isolates observed in Grignon.Finally, phenotyping of the isolate collection also showed the resurgence of an A3 phenotype linked with the loss of AvrLm7 avirulence in more than 98% of the isolates. Genetic analysis and collection phenotyping showed that AvrLm3 is not a new AvrLm4-7 allele but a distinct gene located in a telomeric region at 19.3 cM of AvrLm4-7. I also demonstrated that an antagonistic interaction between AvrLm4-7 and AvrLm3 exists: the presence of Avrlm4-7 prevents Rlm3 to detect AvrLm3 and explains the surge of the AvrLm3 avirulence along with the loss of the AvrLm7 avirulence.By an original association of molecular biology, population genetic and agronomy, this work provided a new illustration of the plant-pathogen arms race, AvrLm3 and AvrLm4-7 using two different strategies to escape their respective resistance genes.