Sympatric ascochyta complex of wild Cicer judaicum and domesticated chickpea

Abstract

The aim of this study was to isolate, identify and characterize ascochyta blight pathogens from Cicer judaicum, a wild annual Cicer species which grows in Israel and other Mediterranean countries in sympatric distribution with legume crops, and determine their virulence and aggressiveness to other wild and domesticated legumes. Native C. judaicum plants exhibited symptoms resembling ascochyta diseases of grain legume crops. Two distinct pathogens were isolated and identified as Phoma pinodella and Didymella rabiei using morphological and molecular tools; their infectivity was verified using Koch's postulates. The virulence of these pathogens was examined on 13 legume species, of which P. pinodella was virulent to Pisum sativum, P. fulvum, C. judaicum, C. arietinum, C. reticulatum, C. pinnatifidum and C. bijugum. Didymella rabiei infected all these Cicer species, but not the other legume species tested. Aggressiveness of the pathogens was tested on wild and domesticated chickpea and pea. Didymella rabiei isolated from C. judaicum had significantly higher (P < 0·001) aggressiveness than P. pinodella from C. judaicum on both wild and domesticated chickpea. Disease severity on the former species ranged from 62·5% to 70% and on the latter from 41% to 56%. Phoma pinodella isolates from C. judaicum were more aggressive on C. arietinum and P. sativum than on C. judaicum and P. fulvum. Results of the current study suggest that C. judaicum may serve as an alternative host to ascochyta pathogens that endanger chickpea and possibly other crops and wild species growing in close proximity.