The SECURE project – Stem canker of oilseed rape: : molecular methods and mathematical modelling to deploy durable resistance

N Evans et al, "The SECURE Project - Stem Canker of oilseed rape: Molecular methods and mathematical modeling to deploy durable resistance", in Vol 4 of the Proceedings of the 12th International Rapeseed Congress : Sustainable Development in Cruciferous Oilseed Crops Production, Wuhan, China, March 26 - 30, 2007. The proceedings are available online at: http://gcirc.org/intranet/irc-proceedings/12th-irc-wuhan-china-2007-vol-4.htmlModelling done during the SECURE project has demonstrated the dynamic nature of the interaction between phoma stem canker (Leptosphaeria maculans), the oilseed rape host (Brassica napus) and the environment. Experiments done with near-isogenic lines of L. maculans to investigate pathogen fitness support field data that suggest a positive effect of the avirulence allele AvrLm4 on pathogen fitness, and that the loss of this allele renders isolates less competitive under field conditions on cultivars without the resistance gene Rlm4. The highlight of molecular work was the cloning of AvrLm1 and AvrLm6. L. maculans is now one of the few fungal species for which two avirulence loci have been cloned. Subsequent research focused on understanding the function of AvrLm1 and AvrLm6 and on the analysis of sequences of virulent isolates to understand molecular evolution towards virulence. Isolates of L. maculans transformed with GFP and/or DsRed were used to follow growth of the fungus in B. napus near-isogenic-lines (NIL) with or without MX (Rlm6) resistance under different temperature and wetness conditions. The results greatly enhanced our knowledge of the infection process and the rate and extent of in planta growth on different cultivars. Conclusions from work to model durability of resistance have been tested under field conditions through a series of experiments to compare durability of resistance conferred by the major resistance gene Rlm6 alone in a susceptible background (EurolMX) or in a resistant background (DarmorMX) under recurrent selection over 4 growing seasons. A major priority of the project was knowledge transfer of results and recommendations to target audiences such as plant breeding companies and extension services. CETIOM developed a “diversification scheme” that encourages French growers to make an informed choice about the cultivars that are grown within the rotation based on the resistance genes carried by the individual cultivars. Use of such schemes, in association with survey data on the population structure of L. maculans at both national and European scales will provide opportunities for breeders and the industry to manage available B. napus resistance more effectively.Non peer reviewe

Patogeniczność Drechslera avenae dla liści wybranych genotypów owsa i jego zdolność do produkcji związków antrachinonowych

Drechslera leaf spot in the common oat (Avena sativa L.) is caused by D. avenae (syn. Pyrenophora chaetomioides, Helminthosporium avenae). Susceptibility of various oat cultivars and breeding lines to leaf infection by this pathogen was investigated in the field in 2001–2002 and in a growth chamber. After natural infection in the field, brown or brown-red spots caused by D. avenae were found in all oat genotypes and both years, but were less common in the drier and colder growing season (2001). Mean values of leaf infection index in the studied oat genotypes for the 2 years varied from 5.65 (CHD 2100) to 10.33 (Akt). After artificial inoculation in the growth chamber, symptoms were similar but leaf infection index was much higher – from 15.0 (Bajka) to 41.3 (STH 4699). High-performance liquid chromatography showed that anthraquinone derivatives produced by strain 1 of D. avenae include anthraquinone compaunds – cynodontin and helminthosporin. These compounds are known to limit the growth of some other pathogens and saprophytes.Plamistość liści owsa (Avena sativa L.) powodowana jest przez gatunek Drechslera avenae (Drechslera chaetomioides, Helmintosporium avenae). Podatność wybranych odmian i rodów hodowlanych owsa na infekcję przez ten patogen badano w warunkach polowych w latach 2001–2002 oraz w fitotronie. W wyniku naturalnej infekcji w warunkach polowych, brązowe lub brązowo-czerwone plamy, powodowane przez D. avenae stwierdzono w przypadku wszystkich genotypów owsa w obu latach badań, ale występowały one w mniejszym nasileniu w sezonie bardziej suchym i chłodniejszym (2001). Średnie wartości indeksu porażenia liści w przypadku badanych genotypów owsa wynosiły od 5.65 (CHD 2100) do 10.33 (Akt). W wyniku sztucznej inokulacji liści owsa w warunkach fitotronowych objawy na liściach były podobne, ale indeks porażenia liści znacznie wyższy – od 15.0 (Bajka) do 41.3 (STH 4699). Badania przy zastosowaniu wysokorozdzielczej chromatografii cieczowej wykazały zdolność do produkcji przez szczep D. avenae nr 1 pochodnych antrachinonowych – cynodontyny i helmintosporyny. Związki te mogą ograniczać wzrost niektórych patogenów i saprotrofów

Epifitoza brunatnej plamistosci lisci w uprawie pszenicy i pszenzyta - badania porownawcze

Development of tan spot epiphytosis in wheat and triticale has been investigated during three years of cropping seasons 1998-2001. The infection level of plants was scored in four stages of cereals development at the end of tillering (GS 29), shooting (GS 35-37), heading (GS 55-59) and milk maturity (GS 73-77). The monitoring performed on population of 327 wheat and 352 triticale genotypes indicated that the both cereals can be heavy infected by P. tritici-repentis, although the reaction of these hosts differed significantly. On triticale developed small, minute black spots usually without typical for wheat yellow halo. Moreover, the progress of tan spot of triticale over time was less rapid and disease intensity lower in the all plant growth stages during three years of studies.Badano rozwój epifitozy brunatnej plamistości liści w uprawie pszenicy i pszenżyta w okresie trzech sezonów wegetacyjnych obejmujących okres 1998-2001. Stopień porażenia roślin oceniano stosując pięciostopniową skalę i przeprowadzano w fazach: krzewienia, strzelania w źdźbło, kłoszenia i dojrzałości mlecznej zbóż. Wykonany monitoring obejmujący populację 327 genotypów pszenicy i 352 pszenżyta wskazał, że obydwa gatunki mogą ulegać silnemu porażeniu. Stwierdzono, że porażenie pszenżyta we wszystkich fazach rozwojowych trzech kolejnych sezonów wegetacyjnych było istotnie niższe niż pszenicy a przebieg epifitozy mniej gwałtowny. Poza istotnymi różnicami o charakterze ilościowym na pszenżycie w początkowych fazach rozwoju choroby reagowało tworząc bardzo drobne nekrozy bez typowego dla pszenicy halo

Formation and Properties of the Ta-Y2O3, Ta-ZrO2, and Ta-TaC Nanocomposites

The nanocrystalline tantalum-ceramic composites were made using mechanical alloying followed by pulse plasma sintering (PPS). The tantalum acts as a matrix, to which the ceramic reinforced phase in the concentration of 5, 10, 20, and 40 wt.% was introduced. Oxides (Y2O3 and ZrO2) and carbides (TaC) were used as the ceramic phase. The mechanical alloying results in the formation of nanocrystalline grains. The subsequent hot pressing in the mode of PPS results in the consolidation of powders and formation of bulk nanocomposites. All the bulk composites have the average grain size from 40 nm to 100 nm, whereas, for comparison, the bulk nanocrystalline pure tantalum has the average grain size of approximately 170 nm. The ceramic phase refines the grain size in the Ta nanocomposites. The mechanical properties were studied using the nanoindentation tests. The nanocomposites exhibit uniform load-displacement curves indicating good integrity and homogeneity of the samples. Out of the investigated components, the Ta-10 wt.% TaC one has the highest hardness and a very high Young’s modulus (1398 HV and 336 GPa, resp.). For the Ta-oxide composites, Ta-20 wt.% Y2O3 has the highest mechanical properties (1165 HV hardness and 231 GPa Young’s modulus)