Abstract
Background: Endophytic bacterial community of plant helps in plant growth and health. However, compositional and functional responses of bacterial endophyte communities in black rice and its correlation with antioxidant property are still not understood. Black scented rice, Chakhao ( Oryza sativa L.) is important for its unique fragrance, high antioxidant and anthocyanin content. Here, the compositional and functional role of the endophytic bacterial community, associated with black scented rice - Chakhao ( Oryza sativa L.) at young and mature stage of plant growth, in correlation with antioxidant property has been elucidated.Result: Bray–Curtis community dissimilarity analysis confirmed overlapping of community in shoot and root tissues at the young stage, but not in mature plants. Proteobacteria was found to be the most dominant phyla, and along with Cyanobacteria and Planctomycetes, it dominated the core endospheric microbiome. The genera Agrobacterium, Pleomorphomonas, Bradyrhizobium, Novasphingobium, Caulobacter, Devosia were the most abundant. The antioxidant activity of mature stage plants was found to be higher in comparison to young plants. The total polyphenol content (TPC) was found to be highest in root of Sempak variety (89.06 µg GAE/g). The relative abundance of Pleomorphomonas was positively correlated with TPC, while Gemmata , Unclassified Pirellulaceae , Unclassified Stramenopiles positively correlated with total flavonoid content (TFC). Accordingly, functional metagenome analysis of the endophytic microbiome revealed that few unique genes (naringenin-3-dioxygenase and anthocyanidin-3-O-glucosyltransferases) for flavonoid and anthocyanin synthesis were abundant in mature stage of plant development. Specific enrichment of the antioxidant producing genes in the mature plant endophytic microbiome was assigned to bacteria such as Streptomyces, Pantoea and Bradyrhizobium , which might have contributed to the common pathway of flavonoid synthesis. Conclusion: This study allows us to recognize the linkage between the endophytic bacterial community dynamics and antioxidant activity of scented black rice plant and its comparative account at young and mature stages of growth.
Effects of gamma radiation on the stability and degradation kinetics of phenolic compounds and antioxidant activity during storage of (Oryza sativa L.) black rice flour
