Uncovering functional deterioration in the rhizosphere microbiome associated with post-green revolution wheat cultivars

During the Green Revolution, one of the biggest developments of wheat domestication was the development of new cultivars that respond well to fertilisers and produce higher yields on shorter stems to prevent lodging. Consequently, this change has also impacted the wheat microbiome, often resulting in reduced selection of taxa and a loss of network complexity in the rhizospheres of modern cultivars. Given the importance of rhizosphere microbiomes for plant health and performance, it is imperative that we understand if and how these changes have affected their function. Here, we use shotgun metagenomics to classify the functional potential of prokaryote communities from the rhizospheres of pre-green revolution (heritage) cultivars to compare the impact of modern wheat breeding on rhizosphere microbiome functions. Results

We found distinct taxonomic and functional differences between heritage and modern wheat rhizosphere communities and identified that modern wheat microbiomes were less distinct from the communities in the surrounding soil. Of the 113 functional genes that were differentially abundant between heritage and modern cultivars, 95% were depleted in modern cultivars and 65% of differentially abundant reads best mapped to genes involved in staurosporine biosynthesis (antibiotic product), plant cell wall degradation (microbial mediation of plant root architecture, overwintering energy source for microbes) and sphingolipid metabolism (signal bioactive molecules). Conclusions

Overall, our findings indicate that green revolution breeding has developed wheat cultivars with a reduced rhizosphere effect. The consequences of this are likely detrimental to the development of microbiome-assisted agriculture which will require a strong rhizosphere selective environment for the establishment of a beneficial plant root microbiome. We believe our results are of striking importance and highlight that implementation of microbiome facilitated agriculture will benefit from deliberately incorporating the development of beneficial plant-microbiome interactions, alongside traditional yield traits, to advance sustainable wheat production.