Genome and transcriptome–wide analysis of WRKY transcription factors for Pratylenchus coffeae resistance in banana.

Abstract

Plant WRKY transcription factors (WRKY TFs) have a long evolutionary history and are involved in the regulation of various physiological processes, such as development, senescence and in-plant response to many biotic and abiotic stresses. To understand the role of WRKY TFs during a Musa-Pratylenchus coffeae (root lesion nematode) interaction, genome- and transcriptome-wide analyses were carried out. A total of 153 banana WRKY TFs (MusaWRKYs) were identified using public databases. According to their structural and phylogenetic features, they were classified into three main groups. In order to identify the role of MusaWRKY genes in the banana reaction to P. coffeae, the MusaWRKY expression profiles were examined from the nematodechallenged and unchallenged transcriptomic data both from a resistant cultivar ‘Karthobiumthum’ (ABB) and a susceptible cultivar ‘Nendran’ (AAB). It was observed that 121 MusaWRKYs were expressed in both the resistant and susceptible cultivar, whereas 32 MusaWRKYs were not expressed even after having been challenged with P. coffeae. Interestingly it was noted that more MusaWRKYs were significantly upregulated in the resistant (39.6%) than in the susceptible (28.5%) cultivar. Upregulation of more number of group IIc WRKYs (13 genes) in resistant cultivar revealed the significance of group IIc WRKYs in nematode resistant mechanism. Significant expression of MusaWRKY95 only in the nematode-challenged resistant cultivar emphasizes the importance of its role in Musa-P. coffeae incompatible interaction. Thus, isolation of full length genes of MusaWRKY95 and MusaWRKY142 are in progress for understanding their function during Musa-P. coffeae interaction, particularly with regard to any role in pathogen resistance.