Proteomic and Transcriptomic Analysis for Identification of Endosymbiotic Bacteria Associated with BYDV Transmission Efficiency by Sitobion miscanthi

Sitobion miscanthi, an important viral vector of barley yellow dwarf virus (BYDV), is also symbiotically associated with endosymbionts, but little is known about the interactions between endosymbionts, aphid and BYDV. Therefore, two aphids' geographic populations, differing in their BYDV transmission efficiency, after characterizing their endosymbionts, were treated with antibiotics to investigate how changes in the composition of their endosymbiont population affected BYDV transmission efficiency. After antibiotic treatment, Rickettsia was eliminated from two geographic populations. BYDV transmission efficiency by STY geographic population dropped significantly, by -44.2% with ampicillin and -25.01% with rifampicin, but HDZ geographic population decreased by only 14.19% with ampicillin and 23.88% with rifampicin. Transcriptomic analysis showed that the number of DEGs related to the immune system, carbohydrate metabolism and lipid metabolism did increase in the STY rifampicin treatment, while replication and repair, glycan biosynthesis and metabolism increased in the STY ampicillin treatment. Proteomic analysis showed that the abundance of symbionin symL, nascent polypeptide-associated complex subunit alpha and proteasome differed significantly between the two geographic populations. We found that the endosymbionts can mediate vector viral transmission. They should therefore be included in investigations into aphid-virus interactions and plant disease epidemiology. Our findings should also help with the development of strategies to prevent virus transmission.