Ascochyta blight (Ascochyta rabiei (Pass.) Lab.) of Chickpea (Cicer arietinum L.): Breeding Strategies for Resistance

Abstract

In the Mediterranean region, chickpea yield could be increased by shifting the sowing date from spring to winter. Nevertheless, this is hampered by the sensitivity of the crop to low temperatures and the fungal disease Ascochyta blight. Ascochyta blight, caused by Ascochyta rabiei (Pass.) Labr., is a devastating disease of chickpea (Cicer arietinum L.) in most of the chickpea-producing countries, including Iran. Severe epidemics of ascochyta blight have occurred many times in various production regions, often on cultivars previously thought to be resistant. The evolution of a new race or virulence form is frequently invoked to explain such outbreaks. Current cultivars only possess partial resistance to the pathogen and this level of resistance can breakdown easily because the pathogen is highly variable due to potential for sexual recombination. Although, the evaluation of the world collection of chickpea germplasm for resistance to ascochyta blight revealed a very low frequency of resistant lines, there are some resistant genotypes in chickpea germplasm which can be used in breeding programs. Marker Assisted Selection (MAS) would allow a better targeting of the desired genes. Genetic mapping in chickpea, for a long time hampered by the little variability in chickpea’s genome, is today facilitated by highly polymorphic, co-dominant microsatellite based markers. More durable resistance could probably be achieved by pyramiding of resistance genes via MAS and is a major challenge for chickpea breeders. Genotypic variation has been reported for ascochyta blight resistance in chickpea using both Mendelian and Quantitative Trait Loci (QTL) analyses, with conflicting reports about the mechanism of resistance. The genetics of resistance to ascochyta blight has been extensively analysed because the disease is of great agronomic and economic importance. In this review, we summarize current situations and future prospect of necessities for changing from spring to winter sowing of chickpea as well as progresses in genome mapping and QTL analysis for ascochyta blight resistance in chickpea.