Tobacco rattle virus-inducedPHYTOENE DESATURASE(PDS)andMg-chelatase H subunit(ChlH) gene silencing inSolanum pseudocapsicumL.

Virus-induced gene silencing (VIGS) is an attractive tool for determining gene function in plants. The present study constitutes the first application of VIGS in S. pseudocapsicum , which has great ornamental and pharmaceutical value, using tobacco rattle virus (TRV) vectors. Two marker genes, PHYTOENE DESATURASE ( PDS ) and Mg-chelatase H subunit ( ChlH ), were used to test the VIGS system in S. pseudocapsicum . The photobleaching and yellow-leaf phenotypes of the silenced plants were shown to significantly correlate with the down-regulation of endogenous SpPDS and SpChlH , respectively ( P  ≤ 0.05). Moreover, the parameters potentially affecting the efficiency of VIGS in S. pseudocapsicum , including the Agrobacterium strain and the inoculation method (leaf syringe-infiltration, sprout vacuum-infiltration and seed vacuum-infiltration), were compared. The optimized VIGS parameters were the leaf syringe-infiltration method, the Agrobacterium strain GV3101 and the growth of agro-inoculated plants at 25°. With these parameters, the silencing efficiency of SpPDS and SpChlH could reach approximately 50% in S. pseudocapsicum . Additionally, the suitability of various reference genes was screened by RT-qPCR using three candidate genes, and the results demonstrated that glyceraldehyde 3-phosphate dehydrogenase ( GAPDH ) can serve as a suitable reference for assessing the gene expression levels of VIGS systems in S. pseudocapsicum . The proven application of VIGS in S. pseudocapsicum and the characterization of a suitable reference gene in the present work will expedite the functional characterization of novel genes in S. pseudocapsicum.