A major genetic locus in neighbours controls changes of gene expression and susceptibility in intra-specific rice mixtures.

Reports indicate that intra-specific neighbours alter the physiology of focal plants and with a few exceptions, their molecular responses to neighbours is unknown. Recently, changes of susceptibility to pathogen resulting from such interactions were demonstrated, a phenomenon called NMS (Neighbour-Modulated Susceptibility). However, the genetics of NMS and the associated molecular responses are largely unexplored. Here we analysed in rice the modification of biomass and susceptibility to the blast fungus pathogen in the Kitaake focal genotype in the presence of 280 different neighbours. Using GWAS we identified the loci in the neighbour that determine the response in Kitaake. Using a targeted transcriptomic approach, we characterized the molecular responses in focal plants co-cultivated with various neighbours inducing a reduction of susceptibility. Our study demonstrates that NMS is controlled by one major locus in the rice genome of its neighbour. Furthermore, we show that this locus can be associated with characteristic patterns of gene expression in focal plant. Finally, we propose an hypothesis where Pi could play a role in explaining this case of NMS. Our study sheds lights on how plants affect the physiology in their neighbourhood and opens perspectives for understanding plant-plant interactions.