Application of VIGS system to explore the function of common wheat TaADF7

As an allohexaploid plant, common wheat has a complex gene structure, making it difficult to study its gene function. Virus-induced gene silencing (VIGS) is an important tool for the rapid analysis of plant gene function. In this study, the gene silencing system, namely, barley stripe mosaic virus (BSMV)-VIGS induced by BSMV was used to silence the wheat phytoene desaturase (TaPDS) and actin depolymerization factor (TaADF7) genes and determine the effect of gene silencing on wheat. TaPDS was used as an indicator gene to determine the feasibility of VIGS system, while TaADF7 was used as a test gene to determine its effect on wheat growth. Results showed that the leaves of tobacco and wheat were bleached by the mixture of pCaBS-α, pCaBS-β, and pCaBS-γ::TaPDS, indicating that the TaPDS gene was silenced, and the bleached leaves had physiological activity as determined by trypan blue staining. Therefore, the VIGS system was efficient and available. After the tobacco was treated with pCaBS-α, pCaBS-β, and pCaBS-γ::TaADF7, the viral suspension was obtained. The expression of TaADF7 gene was downregulated after wheat leaves were infected by friction, indicating that the expression of TaADF7 was silenced. Laser confocal scanning microscopy showed that the silencing of TaADF7 enhanced the fluorescence of microfilament skeleton in mesophyll protoplasts and significantly reduced the plant height. Results showed that TaADF7 affected cell division and plant growth by inhibiting microfilament depolymerization. In conclusion, the BSMV-VIGS system was used to silence wheat TaPDS and TaADF7 genes. Bleaching phenomenon was observed in wheat leaves after TaPDS silencing. After TaADF7 silencing, microfilaments in wheat mesophyll cells gathered into coarse bundles, which affected the dynamics of microfilaments and inhibited plant growth.