Abstract

                                Nodule associated endophytic yeasts have attracted much attention dueto its potential plant growth-promoting activities and protecting legumecrops from both biotic and abiotic stress. The present study evaluated thepotential role of an endophytic yeast Candida tropicalis VYW1 in modulatinghost fitness (blackgram) both as a single inoculant and co-inoculant withRhizobium sp. VRE1. The results showed that nodule associated endophyticyeast C. tropicalis VYW1 when co-inoculated with Rhizobium sp. VRE1significantly increased the germination percent (100%), root (34.6 cm),and shoot length (32.8 cm). The vigor index was also maximum (4250) inthe treatment that received the co-inoculation of Rhizobium sp. VRE1 andC. tropicalis VYW1 besides registering enhanced hydrolytic enzyme,α - amylase, and protein content in seeds. Metabolite profiling of bacterialprimed seed exudates revealed 30 diverse compounds belonging to theclasses viz., sugars, amino acids, organic acids, flavones, prenol lipids,and fatty acids. The blackgram seeds primed with co - inoculants releasedhydroxyl benzoic acid and galactopyranose, which act as potential chemoattractantsand involves in the lectin complement pathway regulatingfructose mannose metabolism. These metabolites lead to a significantincrease in germination and nodulation in blackgram seedlings. Hence,the study suggests the scope of enhancing the fitness of blackgram usinga co-inoculant comprising of C. tropicalis VYW1 and Rhizobium sp. VRE1.

Key words : Blackgram; Co-inoculant; Nodules; Non-Rhizobial endophytes; Rhizobium