INTRODUCTION

With current trends in global climate change, both flooding episodes and higher levels of CO have been key factors to impact plant growth and stress tolerance. Very little is known about how both factors can influence the microbiome diversity and function, especially in tolerant soybean cultivars. This work aims to (i) elucidate the impact of flooding stress and increased levels of CO on the plant defenses and (ii) understand the microbiome diversity during flooding stress and elevated CO (eCO).

METHODS

We used next-generation sequencing and bioinformatic methods to show the impact of natural flooding and eCO on the microbiome architecture of soybean plants' below- (soil) and above-ground organs (root and shoot). We used high throughput rhizospheric extra-cellular enzymes and molecular analysis of plant defense-related genes to understand microbial diversity in plant responses during eCO and flooding.

RESULTS

Results revealed that bacterial and fungal diversity was substantially higher in combined flooding and eCO treatments than in non-flooding control. Microbial diversity was soil>root>shoot in response to flooding and eCO. We found that sole treatment of eCO and flooding had significant abundances of , and . Whereas the combination of flooding and eCO2 conditions showed a significant abundance of and . Rhizospheric extra-cellular enzyme activities were significantly higher in eCO than flooding or its combination with eCO. Plant defense responses were significantly regulated by the oxidative stress enzyme activities and gene expression of and in floodings and eCO treatments in soybean plant root or shoot parts.

CONCLUSION

This work suggests that climatic-induced changes in eCO and submergence can reshape microbiome structure and host defenses, essential in plant breeding and developing stress-tolerant crops. This work can help in identifying core-microbiome species that are unique to flooding stress environments and increasing eCO.