Shifts inBuchnera aphidicoladensity in soybean aphids (Aphis glycines) feeding on virus-infected soybean

Abstract

Vertically transmitted bacterial symbionts are common in arthropods. Aphids undergo an obligate symbiosis with Buchnera aphidicola, which provides essential amino acids to its host and contributes directly to nymph growth and reproduction. We previously found that newly adult Aphis glycines feeding on soybean infected with the beetle-transmitted Bean pod mottle virus (BPMV) had significantly reduced fecundity. We hypothesized that the reduced fecundity was attributable to detrimental impacts of the virus on the aphid microbiome, namely Buchnera. To test this, mRNA sequencing and quantitative real-time PCR were used to assay Buchnera transcript abundance and titre in A. glycines feeding on Soybean mosaic virus-infected, BPMV-infected, and healthy soybean for up to 14 days. Our results indicated that Buchnera density was lower and ultimately suppressed in aphids feeding on virus-infected soybean. While the decreased Buchnera titre may be associated with reduced aphid fecundity, additional mechanisms are probably involved. The present report begins to describe how interactions among insects, plants, and plant pathogens influence endosymbiont population dynamics.

Stress‐induced changes in abundance differ among obligate and facultative endosymbionts of the soybean aphid

“…This result suggests the metabolic interdependence of obligate symbiont and insect host may increase sensitivity to external stress, such that a low threshold level of aphid stress will adversely affect abundance. Similar reductions in Buchnera density have been observed in soybean aphids fed on virus-infected plants (Cassone et al 2015) and in the pea aphid following heat shock (Dunbar et al 2007). Age and aphid genotype have also proven to be primary factors contributing to changes in Buchnera titer in A. pisum (Vogel and Moran 2011;Martinez et al 2014).…”

“…Similar reductions in Buchnera density have been observed in soybean aphids fed on virus‐infected plants (Cassone et al. 2015) and in the pea aphid following heat shock (Dunbar et al. 2007).…”

The genetic diversity of SMLS (Sitobion miscanthi L type symbiont) and its effect on the fitness, mitochondrial DNA diversity and Buchnera aphidicola dynamic of wheat aphid, Sitobion miscanthi (Hemiptera: Aphididae)

“…) and plant viruses (Cassone et al . ). Hence, it is striking that there were generally higher B. aphidicola densities observed in SMLS‐infected S. miscanthi populations.…”

“…The decline and resurgence of B. aphidicola populations at the mid-stages of development were likely due to a mismatch of the rates of proliferation and consumption. It is expected that density of B. aphidicola would be suppressed by secondary symbionts (Koga et al 2003;Sakurai et al 2005) and plant viruses (Cassone et al 2015). Hence, it is striking that there were generally higher B. aphidicola densities observed in SMLS-infected S. miscanthi populations.…”

Soybean mosaic virus: a successful potyvirus with a wide distribution but restricted natural host range

“…Although A. glycines is capable of transmitting SMV experimentally (Clark and Perry, 2002;Hill et al, 2001), it is a poor vector in the field (Wang and Ghabrial, 2002). The growth rates of A. glycines on SMV-infected plants are often significantly lower than on healthy soybean plants (Cassone et al, 2015;Donaldson and Gratton, 2007;Penaflor et al, 2016). SMV isolates can differ significantly in their rates of transmission by a single aphid species Lucas and Hill, 1980;O'Connell Ziegler et al, 1986).…”