Identification of Novel Sources of Ascochyta Blight Resistance in Wild Relatives of Chickpea

Abstract

Ascochyta blight, caused by Ascochyta rabiei, is the most devastating disease affecting global chickpea production and is currently managed with partially resistant varieties and multiple fungicide applications in years of the epidemic. However, the identification of new pathotypes that are resistant to commonly used fungicides and increased aggressiveness against the current germplasm puts the sustainability of chickpea production under constant threat. Thus, identifying novel sources of genetic resistance against highly aggressive Ascochyta rabiei pathotypes followed by transfer to chickpea varieties is the first step in effective disease management. In this study, 90 chickpea accessions representing eight Cicer species were evaluated for ascochyta blight resistance using a reliable controlled conditions screening method against an A. rabiei pathotype prevalent in the Pacific Northwest, USA. The mean disease score across accessions ranged from 1.25 to 9 on a 1–9 rating scale, with 1 being the most resistant. Out of the eight Cicer species, the highest level of disease resistance was identified in C. bijugum and C. echinospermum germplasm, with the lowest disease scores of 1.25 and 2.82, respectively. Additional germplasm characterization based on the mean disease and disease spread across biological replicates revealed six novel accessions with a high level of genetic resistance, with a mean disease score between 1.25 and 1.8.