With the development of genetic maps and the identification of the most-likely positions of quantitative trait loci (QTLs) on these maps, molecular markers for lodging resistance can be identified. Consequently, marker-assisted selection (MAS) has the potential to improve the efficiency of selection for lodging resistance in a breeding program. This study was conducted to identify genetic loci associated with lodging resistance, plant height and reaction to mycosphaerella blight in pea. A population consisting of 88 recombinant inbred lines (RILs) was developed from a cross between Carneval and MP1401. The RILs were evaluated in 11 environments across the provinces of Manitoba, Saskatchewan and Alberta, Canada in 1998, 1999 and 2000. One hundred and ninety two amplified fragment length polymorphism (AFLP) markers, 13 random amplified polymorphic DNA (RAPD) markers and one sequence tagged site (STS) marker were assigned to ten linkage groups (LGs) that covered 1,274 centi Morgans (cM) of the pea genome. Six of these LGs were aligned with the previous pea map. Two QTLs were identified for lodging resistance that collectively explained 58% of the total phenotypic variation in the mean environment. Three QTLs were identified each for plant height and resistance to mycosphaerella blight, which accounted for 65% and 36% of the total phenotypic variation, respectively, in the mean environment. These QTLs were relatively consistent across environments. The AFLP marker that was associated with the major locus for lodging resistance was converted into the sequence-characterized amplified-region (SCAR) marker. The presence or absence of the SCAR marker corresponded well with the lodging reaction of 50 commercial pea varieties.

SummaryWe initiated a proteomics‐based approach to identify root proteins affected by salinity in pea (Pisum sativum cv. Cutlass). Salinity stress was imposed either on 2‐wk old pea plants by watering with salt water over 6 wk or by germinating and growing pea seeds for 7 days in Petri dishes. Concentrations of NaCl above 75 mM had significant negative effects on growth and development of peas in both systems. Salinity‐induced root proteome‐level changes in pea were investigated by 2‐D electrophoresis of proteins from control, 75 and 150 mM NaCl‐treated plants and seedlings. The majority of the protein spots visualised showed reproducible abundance in root protein extracts from whole plants and seedlings. Of these proteins, 35 spots that exhibited significant changes in abundance due to NaCl treatment were selected for identification using ESI‐Q‐TOF MS/MS. The identities of these proteins, which include pathogenesis‐related (PR) 10 proteins, antioxidant enzymes such as superoxide dismutase (SOD) as well as nucleoside diphosphate kinase (NDPK) are presented, and the roles of some of them in mediating responses of pea to salinity are discussed. This is the first report of salinity‐induced changes in the root proteome of pea that suggests a potential role for PR10 proteins in salinity stress responses. Our findings also suggest the possible existence of a novel signal transduction pathway involving SOD, H2O2, NDPK and PR10 proteins with a potentially crucial role in abiotic stress responses.

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2007. Sensitivity of field populations of Ascochyta rabiei to chlorothalonil, mancozeb, and pyraclostrobin fungicides, and effects of strobilurin fungicides on the progress of ascochyta blight of chickpea. Can. J. Plant Sci. 87: 937-944. Chickpea production faces a major challenge from ascochyta blight (Ascochyta rabiei), a devastating disease that can cause total crop loss. To assess the effect of repeated fungicide application on disease progress, strobilurin fungicides, primarily alternating pyraclostrobin and azoxystrobin treatments, were applied up to five times per year in each of 2 yr. A single application or two early applications reduced blight severity. A third application resulted in additional benefits in 1 of 2 yr, but additional applications did not reduce severity further. To monitor for fungicide tolerance in populations of A. rabiei, 66 single-spore isolates were collected and grown on growth media amended with chlorothalonil, mancozeb, or pyraclostrobin. Insensitivity to one or more of the fungicides was detected in 49 (74%) of the isolates. Based on the effect on conidial germination, insensitivity to pyraclostrobin or chlorothalonil was observed in 26 of 37 isolates (70%). Repeated fungicide application may be selecting for insensitive isolates of the pathogen; fungicide application should be combined with cultural measures to control ascochyta blight. des populations naturelles de Ascochyta rabiei au chlorothalonil, au mancozèbe et à la pyraclostrobine, et incidence des fongi-cides à la strobilurine sur la progression de la brûlure ascochytique chez le pois chiche. Can. J. Plant Sci. 87: 937-944. La brûlure ascochytique (Ascochyta rabiei), maladie dévastatrice pouvant détruire complètement une culture, pose un sérieux prob-lème aux producteurs de pois chiches. Afin d'évaluer l'incidence d'un usage répétitif de fongicide sur la progression de la mal-adie, les auteurs ont appliqué des fongicides à la strobilurine, principalement de la pyraclostrobine et de l'azoxystrobine en alternance, jusqu'à cinq fois par année pendant deux ans. Une seule application ou deux applications précoces de fongicide atténu-ent la gravité de la maladie. Une troisième application a eu des effets bénéfiques additionnels une année mais pas l'autre. Les applications supplémentaires n'ont pas réduit la gravité de la maladie davantage. Pour déterminer la tolérance de A. rabiei aux fongicides, les auteurs ont recueilli 66 isolats d'une spore qu'ils ont cultivés sur un milieu de croissance contenant du chlorothalonil, du mancozèbe ou de la pyraclostrobine. Quarante-neuf (74 %) des isolats étaient insensibles à un ou à plusieurs fongicides. D'après la germination des conidies, on a décelé l'insensibilité à la pyraclostrobine ou au chlorothalonil chez 26 des 37 isolats (70 %). L'application répétitive de fongicide pourrait favoriser la sélection d'isolats insensibles du pathogène; il con-viendrait de combiner le traitement antiparasitaire à des méthodes de lutte culturales pour combattre la brûlure ascochytique.

. 2003. Etiology, impact and control of rhizoctonia seedling blight and root rot of chickpea on the Canadian Prairies. Can. J. Plant Sci. 83: 959-967. Studies were undertaken to assess the impact of seedling blight and root rot caused by Rhizoctonia solani AG-4 on nodulation and seed yield of chickpea. The effects of pathogen inoculum concentration and seed damage on disease severity were also measured. Chickpea seedlings were grown under controlled-environment conditions in sterilized soil amended with pathogenic isolates of R. solani and in field plot experiments where the inoculum was incorporated with the seed at planting. In greenhouse experiments, emergence and dry matter production declined and root rot severity increased with increasing inoculum concentration. Root rot reduced nodulation where lesions covered more than 25% of the root surface. For chickpea cultivar Sanford this level of infection was sufficient to reduce root mass, but for the cultivar Tyson, more than half of the root was covered with lesions before root mass began to decline. In a comparison of seed treatment fungicides, thiram + carbathiin (Vitaflo 280) and carbathiin + thiabendazole (Crown at 6 mL of product kg -1 seed) significantly increased seedling emergence and seed yield compared to the inoculated control. In an assessment of the effects of seed damage, seedling survival and seed yield were similar for both healthy and mechanically damaged seed. Rhizoctonia solani has the potential to be an important constraint to chickpea production in the prairie region of western Canada. 83: 959-967. Les auteurs ont essayé d'évaluer l'incidence de la brûlure et du piétin causés par Rhizoctonia solani AG-4 sur la nodulation et le rendement grainier du pois chiche. Ils ont aussi déterminé dans quelle mesure la gravité de la maladie était influencée par la concentration de l'inoculum pathogène et les graines abîmées. Les plantules de pois chiche ont été cultivées en milieu contrôlé, dans du sol stérilisé auquel on a ajouté un isolat pathogène de R. solani, et sur des parcelles expérimentales, au sol desquelles on a incorporé l'inoculum avec la graine, à la plantation. Lors des expériences en serre, l'usage d'un inoculum de plus en plus concentré entraîne une baisse du taux de levée et de la production de matière sèche ainsi qu'une hausse de la gravité du piétin. Le piétin réduit la nodulation quand les lésions couvrent plus de 25 % de la surface des racines. Avec le cultivar Sanford, ce degré d'infection suffit à réduire la masse des racines, mais avec de Tyson, cette dernière ne diminue que lorsque plus de la moitié des racines sont couvertes de lésions. Lors d'un essai comparatif sur les fongicides destinés aux semences, l'usage de thiram + carbathiin (Vitaflo 280) et de carbathiin + thiabendazole (Crown, à raison de 6 ml par kg de semences) entraîne une hausse sensible du taux de levée et du rendement grainier par rapport au témoin inoculé. En ce qui concerne les graines endommagées, le taux de survie des plantules et le rendement grainier r...