The WRKY family of transcription factors orchestrate the reprogrammed expression of the complex network of defense genes at various biotic and abiotic stresses. Within the last 96 million years, three rounds of Musa polyploidization events had occurred from selective pressure causing duplication of MusaWRKYs with new activities. Here, we identified a total of 153 WRKY transcription factors available from the DH Pahang genome. Based on their phylogenetic relationship, the MusaWRKYs available with complete gene sequence were classified into the seven common WRKY sub-groups. Synteny analyses data revealed paralogous relationships, with 17 MusaWRKY gene pairs originating from the duplication events that had occurred within the Musa lineage. We also found 15 other MusaWRKY gene pairs originating from much older duplication events that had occurred along Arecales and Poales lineage of commelinids. Based on the synonymous and nonsynonymous substitution rates, the fate of duplicated MusaWRKY genes was predicted to have undergone sub-functionalization in which the duplicated gene copies retain a subset of the ancestral gene function. Also, to understand the regulatory roles of MusaWRKY during a biotic stress, Illumina sequencing was performed on resistant and susceptible cultivars during the infection of root lesion nematode, Pratylenchus coffeae. The differential WRKY gene expression analysis in nematode resistant and susceptible cultivars during challenged and unchallenged conditions had distinguished: 1) MusaWRKYs participating in general banana defense mechanism against P.coffeae common to both susceptible and resistant cultivars, 2) MusaWRKYs that may aid in the pathogen survival as suppressors of plant triggered immunity, 3) MusaWRKYs that may aid in the host defense as activators of plant triggered immunity and 4) cultivar specific MusaWRKY regulation. Mainly, MusaWRKY52, -69 and -92 are found to be P.coffeae specific and can act as activators or repressors in a defense pathway. Overall, this preliminary study in Musa provides the basis for understanding the evolution and regulatory mechanism of MusaWRKY during nematode stress.

Yam bean (Pachyrhizus erosus (L.) Urban) is an underutilised tuberous legume crop which has great potential as a food crop. As a root crop, it produces high yields and as a legume, it can produce protein‐rich food. The phenological growth stages of yam bean are first described here using BBCH (Biologische Bundesanstalt, Bundessortenamnt and Chemische Industrie) scale. We have developed a basic and extended numerical BBCH scale for the identification of different phenological growth stages of yam bean. All phenological stages, including germination (stage 0), leaf development (stage 1), formation of side shoots (stage 2), stem elongation (stage 3), tuber formation (stage 4), inflorescence emergence (stage 5), flowering (stage 6), development of pods (stage 7), ripening of pods (stage 8) and senescence (stage 9) are described using the BBCH scale. This BBCH phenological study in yam bean will be helpful for better crop management, crop improvement and characterisation of germplasm. This scale will also be useful for the yield enhancement of this crop as an emerging underutilised tuber crop.