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RNA-dependent RNA polymerase 1 delays the accumulation of viroids in infected plants |
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| Authors: | Shuai Li Zhixiang Zhang Changyong Zhou Shifang Li |
| Institution: | 1. State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
Citrus Research Institute, Chinese Academy of Agricultural Sciences/Southwest University, Chongqing, China;2. State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China;3. Citrus Research Institute, Chinese Academy of Agricultural Sciences/Southwest University, Chongqing, China |
| Abstract: | RNA-dependent RNA polymerase 1 (RDR1) is essential for plant antiviral defence, but its role in plant defence against viroid infection remains unknown. The present study aimed to identify the function and mechanism of RDR1 in plant resistance to viroid infection. Overexpression of Nicotiana tabacum RDR1 (NtRDR1) delayed the accumulation of potato spindle tuber viroid (PSTVd) genomic RNA and PSTVd-derived small RNA (sRNA) in Nicotiana benthamiana plants at the early invasion stage, but not in the late stage of infection. Conversely, virus-induced gene silencing of tomato RDR1 (SlRDR1a) increased the susceptibility to PSTVd infection (increased viroid accumulation). Salicylic acid (SA) pretreatment induced SlRDR1a expression and enhanced the defence against PSTVd infection in tomato plants. Our study demonstrated that RDR1 is involved in SA-mediated defence and restricts the early systemic invasion by PSTVd in plants. The decreased PSTVd accumulation in N. benthamiana was not caused by efficient accumulation of PSTVd sRNAs. These results deepen our understanding of the mechanism of RDR1 in plant defence responses to viroid attack. |
| Keywords: | RDR1 resistance RNA silencing SA salicylic acid tobacco tomato viroid |