Symbiont dominance and microbiome dysbiosis in wheat-aphid revealed through 16 S rRNA gene amplicon sequencing analysis.

Insect herbivory represents a major biotic stress that leads to significant losses in crop yield and quality worldwide. Aphids, in particular, damage wheat (Triticum aestivum L.), a staple crop that provides nearly 20% of the global protein and caloric intake, and also harbor diverse bacterial symbionts that can influence plant health. In this study, 16 S rRNA gene amplicon sequencing was used to characterize the bacterial communities associated with healthy and aphid-infested wheat plants. Alpha-diversity indices, including Simpson, Shannon, Chao1, and ACE, revealed statistically significant variation (P < 0.05) in bacterial richness and diversity across the samples. Richness estimates ranged from 101.25 to 137.2 (Chao1) and 106.04 to 139.37 (ACE), while diversity metrics ranged from 0.428 to 1.243 for the Shannon index, with Faith's phylogenetic diversity varying from 1.27 to 1.48 and Pielou's evenness from 0.626 to 0.740. In healthy wheat plants, Spirodela accounted for approximately 4% of the bacterial community, whereas about 95% of taxa remained unclassified. In contrast, aphid-infested wheat plants contained 3% Spirodela, 7% Buchnera, and 89% unclassified taxa. The aphid microbiome itself was strongly dominated by Buchnera (86%), followed by Pseudomonas (2%) and other minor taxa (1%), with approximately 10% remaining unclassified. The pronounced abundance of Buchnera in both aphids and infested wheat plants highlights its essential nutritional role and its long-standing obligate endosymbiotic association with aphids. Overall, these findings provide new insights into wheat-aphid-microbiome interactions and establish a foundation for developing microbiome-informed pest management strategies.