Genome-Wide Identification of Dicer-Like, Argonaute, and RNA-Dependent RNA Polymerase Gene Families inBrassicaSpecies and Functional Analyses of Their Arabidopsis Homologs in Resistance toSclerotinia sclerotiorum.
RNA silencing is an important mechanism to regulate gene expression and antiviral defense in plants. Nevertheless, RNA silencing machinery in the important oil cropBrassica napusand function in resistance to the devastating fungal pathogenSclerotinia sclerotiorumare not well-understood. In this study, gene families of RNA silencing machinery inB. napuswere identified and their role in resistance toS. sclerotiorumwas revealed. Genome of the allopolyploid speciesB. napuspossessed 8Dicer-like(DCL), 27Argonaute(AGO), and 16RNA-dependent RNA polymerase(RDR) genes, which included almost all copies from its progenitor speciesB. rapaandB. oleraceaand three extra copies ofRDR5genes, indicating that theRDR5group inB. napusappears to have undergone further expansion through duplication during evolution. Moreover, compared with Arabidopsis, someAGOandRDRgenes such asAGO1, AGO4, AGO9, andRDR5had significantly expanded in theseBrassicaspecies. Twenty-one out of 51DCL, AGO, andRDRgenes were predicted to contain calmodulin-binding transcription activators (CAMTA)-binding site (CGCG box).S. sclerotioruminoculation strongly induced the expression ofBnCAMTA3genes while significantly suppressed that of some CGCG-containing RNA silencing component genes, suggesting that RNA silencing machinery might be targeted by CAMTA3. Furthermore, Arabidopsis mutant analyses demonstrated thatdcl4-2, ago9-1, rdr1-1, rdr6-11, andrdr6-15mutants were more susceptible toS. sclerotiorum, whiledcl1-9was more resistant. Our results reveal the importance of RNA silencing in plant resistance toS. sclerotiorumand imply a new mechanism of CAMTA function as well as RNA silencing regulation.
Institute of Biotechnology, College of Agriculture and Biotechnology, Zhejiang University Hangzhou, China.
Jia-Yi
JY
Cao
Center of Analysis and Measurement, Zhejiang University Hangzhou, China.
You-Ping
YP
Xu
Institute of Biotechnology, College of Agriculture and Biotechnology, Zhejiang University Hangzhou, China.
Wen
W
Li
Institute of Biotechnology, College of Agriculture and Biotechnology, Zhejiang University Hangzhou, China.
Shuang-Sheng
SS
Li
Institute of Biotechnology, College of Agriculture and Biotechnology, Zhejiang University Hangzhou, China.
Hafizur
H
Rahman
Institute of Biotechnology, College of Agriculture and Biotechnology, Zhejiang University Hangzhou, China.
Xin-Zhong
XZ
Cai
Argonaute (AGO); Brassica napus; CAMTA3; Dicer-like (DCL); RNA silencing; RNA-dependent RNA polymerase (RDR); Sclerotinia sclerotiorum