The cathepsin S cysteine proteinase of the burrowing nematode Radopholus similis is essential for the reproduction and invasion.
BACKGROUND
The nematode Radopholus similis is an important migratory endoparasite of plants. Cysteine proteinases such as cathepsin S (CPS) play key roles during embryonic development, invasion, and pathogenesis in nematodes and many other animal parasites. This study was designed to investigate the molecular characterization and functions of a cathepsin S protease in R. similis and to find new targets for its control.


RESULTS
Rs-CPS of R. similis, Hg-CPS of Heterodera glycines and Ha-CPS of H. avenae are closely genetically related and share the same branch of the phylogenetic tree. Rs-cps is a multi-copy gene that is expressed in the esophageal glands, ovaries, testes, vas deferens, and eggs of R. similis. Rs-cps mRNA transcripts are expressed at varying levels during all developmental stages of R. similis. Rs-cps expression was highest in females. The neurostimulant octopamine did not significantly enhance the ingestion of the dsRNA soaking solution by R. similis but instead had a detrimental effect on nematode activity. The dsRNA soaking solution diffused into the body of R. similis not only through the esophageal lumen but also through the amphids, excretory duct, vagina, anus and cloacal orifice. We confirmed that RNAi significantly suppressed the expression level of Rs-cps and reproductive capability and pathogenicity of R. similis.


CONCLUSIONS
Our results demonstrate that Rs-cps plays important roles in the reproduction, parasitism and pathogenesis of R. similis and could be used as a new potential target for controlling plant parasitic nematodes.
Laboratory of Plant Nematology and Research Center of Nematodes of Plant Quarantine, Department of Plant Pathology, South China Agricultural University, Guangzhou, 510642 China.
Ke
K
Wang
Laboratory of Plant Nematology and Research Center of Nematodes of Plant Quarantine, Department of Plant Pathology, South China Agricultural University, Guangzhou, 510642 China.|Department of Plant Pathology, Henan Agricultural University, Zhengzhou, 450002 China.
Yu
Y
Li
Laboratory of Plant Nematology and Research Center of Nematodes of Plant Quarantine, Department of Plant Pathology, South China Agricultural University, Guangzhou, 510642 China.
Xin
X
Huang
Laboratory of Plant Nematology and Research Center of Nematodes of Plant Quarantine, Department of Plant Pathology, South China Agricultural University, Guangzhou, 510642 China.
Dong-Wei
DW
Wang
Laboratory of Plant Nematology and Research Center of Nematodes of Plant Quarantine, Department of Plant Pathology, South China Agricultural University, Guangzhou, 510642 China.
Chun-Ling
CL
Xu
Laboratory of Plant Nematology and Research Center of Nematodes of Plant Quarantine, Department of Plant Pathology, South China Agricultural University, Guangzhou, 510642 China.
Hui
H
Xie
Cathepsin S; Cysteine proteinase; Pathogenicity; RNAi; Radopholus similis; Reproduction