Isolation and analysis of candidate ascochyta blight defence genes in chickpea. Part II. Microarray expression analysis of putative defence-related ESTs

Using microarray technology and previously identified defence-related ESTs from chickpea (Cicer arietinum L.), the ascochyta blight (Ascochyta rabiei (Pass.) Labrousse) resistance response was studied in a highly resistant chickpea accession (ICC3996) and a susceptible cultivar (Lasseter). The time-series expression patterns of 20 defence-related ESTs were studied after inoculation with A. rabiei. Ten of the defence-related ESTs displayed up- or down-regulation in ICC3996 and/or Lasseter compared to uninoculated control samples. Hierarchical clustering grouped the ESTs into clusters of similar observations, revealing that three defence related ESTs showed differential up-regulation in ICC3996 when compared to Lasseter-a leucine zipper protein, SNAKIN2 antimicrobial peptide precursor, and elicitor-induced receptor protein. The potential involvement of these ESTs in effective chickpea defence against ascochyta blight is discussed. The microarray expression analysis of defence-related ESTs in chickpea represents the first study of this type, and future work will focus on large-scale expression studies aimed at further elucidating the function of genes involved in ascochyta blight resistance and the pathway of their action.