Salicylic acid deficient Nicotiana benthamiana attenuated virus induced gene silencing but did not affect transgene-induced posttranscriptional gene silencing nor general biogenesis of microRNAs

摘要

RNA interfering (RNAi) is a conserved mechanism in plants which plays a vital role in plant development, response to abiotic stress and biotic stress mediated by endogenous small RNAs and miRNAs as well as small RNAs originated from exogenic RNAs. Salicylic acid (SA) is an important signal in plant resistance to viral infection, functioning in R-gene mediated resistance as well as RNAi. NIbV3, Nicotiana benthamiana (N.benthamiana) transformed with nuclear inclusion b (NIb) gene of plum pox potyvirus (PPV), was reported to recover from PPV infection via virus induced gene silencing (VIGS). In our study, SA deficient NIbV3 plant (NIbV3 expression NahG) delayed recovery from PPV infection; RDR6-deficient NIbV3 (NIbV3 RDR6i) plant could not recovery form PPV infection; furthermore, RDR6i and SA double deficient NIbV3 plant (NIbV3 NahG/RDR6i) accumulated much more virus compared with NIbV3 RDR6i plant. There are no differences between 16c (green fluorescent protein transgenic N. benthamiana) plant and 16c/NahG (SA deficient 16c) plant regarding to GFP mRNA and small interference RNAs accumulation after infiltrated with 35S-GFP or 35S-Fi to trigger post transcriptional gene silencing (PTGS). Among the four selected miRNAs, only miR393 accumulated less in NIbV3/NahG plant than in NIbV3 plant regardless of PPV infection. Other three miRNAs miR159, miR164 and miR167 accumulated similarly between the two genotype plants. Based on our results, we can infer that: 1) SA is an enhancer of VIGS; 2) SA neither affects PTGS nor influences the general miRNAs biogenesis.