Characterization of the salivary effectors involved in the host plant adaptation of pea aphidsCharacterization of the salivary effectors involved in the host plant adaptation of pea aphids

  • Date: Dec 1, 2021
  • Time: 02:00 PM (Local Time Germany)
  • Speaker: Po-Yuan Shih
  • Institute for Genetics, Environment and Plant Protection, Ecology and Genetics of Insects, INRA, Rennes, France
  • Location: Hybrid lecture (online via zoom & MPI-CE, A1.009 + A1.011)

Aphids are crop pests, which suck plant nutrients and transmit viral diseases. During phloem feeding, many salivary proteins are secreted into plants and function like effectors of microbial pathogens. The pea aphid, Acyrthosiphon pisum, encompasses several biotypes each specialized to a few plant species, but the mechanism of the host plant specialization is unclear. Previous genetic and transcriptomic studies of different pea aphid biotypes strongly suggest the involvement of salivary effectors in the determination of the plant specificity. Our recent results found that co-infestation of the pea-adapted biotype enhanced both survival and fecundity of alfalfa-adapted biotype on pea which is not a host of the alfalfa biotype. The electrical penetration graph analysis further demonstrated that the alfalfa biotype showed longer salivation and shorter phloem ingestion on pea compared with the pea biotype. However, the duration of phloem ingestion on pea was significantly extended in the alfalfa biotype co-infested with the pea biotype. These results suggested that pea biotype-specific factors can induce pea susceptibility to the pea non-adapted biotype. In order to evaluate whether salivary effectors are involved in the aphid adaption to pea plants, we selected several salivary effector candidates which are highly expressed in the pea biotype relative to the alfalfa biotype, and then characterized their effect on aphid fitness by transiently expressing these genes in pea. One of the candidates, Ap30, was found to enhance fecundity of pea biotype and several Ap30-interacting pea proteins were identified by a yeast-two hybrid screening, some of them potentially regulating plant immunity. In conclusion, our results support the hypothesis that biotype-specific salivary effectors may be involved in the aphid adaption to specific host plants by inducing the host susceptibility.

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