Characterization of resistance to ascochyta blight of selected wild Cicer germplasm

Abstract

The resistance of 24 perennial Cicer accessions to Ascochyta rabiei (Pass.) Labr. was assessed under field and greenhouse conditions. Two perennial and two annual Cicer accessions with superior resistance were examined and compared with susceptible (‘CDC Xena’) and resistant (‘CDC Frontier’) domesticated Cicer arietinum L. (chickpea) cultivars in terms of pathogen colonization, symptom development, host autofluorescence, and hydrogen peroxide generation. Colonizing hyphae on the four wild Cicer genotypes were pigmented, but hyaline on cultivated chickpea. The morphology of colonizing hyphae differed on the six genotypes, with wider hyphae observed on the most resistant genotype, Cicer anatolicum Alef. PI 383626. Inoculation of leaves of the top five nodes indicated that infection rates were highest on the youngest unfurled leaf for C. anatolicum PI 383626, Cicer oxyodon Boiss. & Hoh. PI 561103, Cicer bijugum Rech.f. ILWC 260, and ‘CDC Frontier’. Observations of hyphal pigmentation, modified hyphal growth, and low infection rates on fully developed leaves of wild Cicer plants suggest that components of the plant surface play an important role in disease resistance. Localized autofluorescence in response to infection was observed in the two perennials, but not in the other genotypes examined. The distinct resistance strategy observed in these perennial accessions make them interesting but challenging candidates for introgression of resistance into cultivated chickpea.