Influence of microbes in mediating sorghum resistance to sugarcane aphids

Abstract

Leaf microbiomes profoundly influence plant health and mediate interactions between plants and their environment. These interactions form a complex relationship that is influenced by the host, microbes, and environment. Similarly, insects, particularly aphids, harbor diverse  obligate symbionts that synthesize essential nutrients for insects and facultative symbionts that enhance host fitness in specific ecological contexts. Sorghum (Sorghum bicolor) is a beneficial and economical food crop that is cultivated worldwide. Since 2013, sorghum production in the United States has been negatively affected by the presence of an invasive piercing-sucking insect pest, sugarcane aphid (SCA; Melanaphis sacchari).  Using the SCA-resistant sorghum line SC265 and the SCA-susceptible sorghum line SC1345, we explored the role of the plant leaf and aphid microbiomes and its role in modulating resistance to SCA by comparing the activation of different microbes upon aphid feeding. The microbiome analysis shows a significant difference in microbial diversity and composition between resistant and susceptible sorghum lines 7 and 14 days after aphid infestation. Alpha diversity metrics, such as observed ASVs and Chao1, indicate significant distinctions. Additionally, beta diversity analysis shows significant difference in microbiome composition between lines, particularly in the absence of the obligate endosymbiont Buchnera aphidicola that resides within the insect hemocoel. These findings contribute to the understanding of the intricate interplay between plant and aphid microbiomes, shedding light on potential avenues to bolster sorghum resistance to sugarcane aphids.