Guo Qiao, Sun Yifan, Ji Chenglong, Kong Zirong, Liu Zhe, Li Yulong, Li Yunzhou, Lai Hangxian
College of Natural Resources and Environment, Northwest A&F University, Xianyang, China.
College of Agriculture, Guizhou University, Guiyang, China.
Front Microbiol. 2023 Oct 6;14:1251698. doi: 10.3389/fmicb.2023.1251698. eCollection 2023.
Tomato yellow leaf curl virus (TYLCV), which is a typical member of the genus , causes severe crop yield losses worldwide. RNA interference (RNAi) is an important antiviral defense mechanism in plants, but whether plant beneficial microbes used as biocontrol agents would modulate RNAi in defense against TYLCV remains unclear.
Here, we employed whole-transcriptome, bisulfite, and small RNA sequencing to decipher the possible role of Ba13 as a bacterial biocontrol agent against TYLCV in RNAi modulation.
Potted tomato plants were exposed to whiteflies for natural viral infection 14 days after bacterial inoculation. Compared with non-inoculated controls, the abundance of TYLCV gene in the leaves of inoculated plants decreased by 70.1% at 28 days post-infection, which mirrored the pattern observed for plant disease index. The expression of the ARGONAUTE family genes (e.g., , and ) involved in antiviral defense markedly increased by 2.44-6.73-fold following bacterial inoculation. The methylation level at CpG site 228 (in the open reading frame region of the RNA interference suppressing gene AV2) and site 461 (in the open reading frame regions of and ) was 183.1 and 63.0% higher in inoculated plants than in non-inoculated controls, respectively. The abundances of 10 small interfering RNAs matched to the TYLCV genome were all reduced in inoculated plants, accompanied by enhancement of photosystem and auxin response pathways.
The results indicate that the application of Ba13 enhances plant resistance to TYLCV through RNAi modulation by upregulating RNAi-related gene expression and enhancing viral genome methylation.
番茄黄化曲叶病毒（TYLCV）是该属的典型成员，在全球范围内导致严重的作物产量损失。RNA干扰（RNAi）是植物中一种重要的抗病毒防御机制，但用作生物防治剂的植物有益微生物是否会调节RNAi以抵御TYLCV仍不清楚。
在此，我们采用全转录组、亚硫酸氢盐和小RNA测序来解读Ba13作为一种细菌生物防治剂在RNAi调节中对TYLCV的可能作用。
在细菌接种14天后，将盆栽番茄植株暴露于粉虱中以进行自然病毒感染。与未接种的对照相比，接种植株叶片中TYLCV基因的丰度在感染后28天下降了70.1%，这与观察到的植物病害指数模式一致。接种细菌后，参与抗病毒防御的AGO蛋白家族基因（如、和）的表达显著增加了2.44 - 6.73倍。接种植株中RNA干扰抑制基因AV2开放阅读框区域的CpG位点228以及和开放阅读框区域的位点461的甲基化水平分别比未接种对照高183.1%和63.0%。接种植株中与TYLCV基因组匹配的10种小干扰RNA的丰度均降低，同时伴随着光系统和生长素反应途径的增强。
结果表明，Ba13的应用通过上调RNAi相关基因表达和增强病毒基因组甲基化来调节RNAi，从而增强植物对TYLCV的抗性。
