兩種寄主專一的begomoviruses於菸草粉蝨體內的相互作用及其對傳播的影響

Abstract

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Polyphagous insects can vector multiple viruses from one or various host plants that leads to mixed infection in susceptible hosts. The interaction between multiple viruses in an insect vector may be classified to be synergistic, antagonistic or neutral and may contribute to a huge shift in the disease epidemics. However, only few studies examined the virus-virus interaction in vector, and its ecological implication remains to be elucidated. The current study examined the interaction of two host-specific begomoviruses, squash leaf curl Philippines virus (SqLCPV), and tomato yellow leaf curl Thailand virus (TYLCTHV) that are transmitted by a polyphagous vector, Bemisia tabaci. A series of experiments were performed to study whether the acquisition of one virus affects the acquisition, infection and transmission of the other. The results revealed that pre-acquisition of SqLCPV had no effect on TYLCTHV acquisition, whereas acquisition of SqLCPV was restrained by TYLCTHV if the whiteflies were only fed for 3 h and the suppression gradually disappeared with increasing acquisition access period (AAP). As an approach to decipher the interaction of the two host-specific begomoviruses in B. tabaci body, quantitative polymerase chain reaction (qPCR) was performed to show the interaction of SqLCPV and TYLCTHV. The results provided a conclusive evidence that SqLCPV and TYLCTHV demonstrated a neutral interaction. Subsequently, saliva of whiteflies was collected in double-distilled water after the whiteflies acquired viruses from a virus-infected plant or two virus-infected plants successively and the titers of both viruses were quantified. The results showed that pre-acquisition of neither SqLCPV nor TYLCTHV had an interference on the counter-virus. Also to note, TYLCTHV exhibited higher titers in the saliva compared with SqLCPV, irrespective of its order of acquisition. Transmission of the two viruses to their respective host plants depicted a clear pattern of infection similar to the titers observed in the saliva of whiteflies. Higher titer of TYLCTHV and lower titer of SqLCPV in saliva corresponded to higher and lower accumulation of TYLCTHV and SqLCPV, respectively in their test plants, nevertheless other host-related factors have to be considered. Altogether, these findings illustrate a plausible neutral interaction between the two viruses in B. tabaci, and further interaction studies may have a significant impact on the disease incidence on a wide scale.