Cyanobacteria is uniquely enriched in the roots of grain amaranths

Abstract

Plants and microbes have coexisted for millions of years and some have evolved mechanisms to achieve symbiosis driving positive selection. The bartering of chemicals produced by soil microbes and plants favour enrichment of certain types of bacteria near the roots that offers selective advantage to the plant under a given environment. Grain amaranths display certain important agronomic characteristics like C4 dicot, high protein and high lysine grains, resistance to biotic and abiotic stress, which can be translated to other crops. Considering an unusual collection of desirable traits shown by grain amaranths, it is worth pondering if symbiosis with bacteria has played any role in these traits. The objective of this study is to identify bacterial root microflora unique to grain amaranths. Here, by comparing rhizospheric and endophytic composition of 16S rRNA from various sections of roots from selected species under major plant orders including the three varieties of grain amaranths, we report that Cyanobacteria are uniquely enriched by grain amaranths. The diversity in OTUs among the Cyanobacteria also significantly increased among samples from amaranth species compared to negative control. This finding is also validated using root transcriptome of Amaranthus hypochondriacus, where we observe relative increase in Cyanobacterial population between day 15 to day 30 compared to other abundant phylum during this period.