Instar-dependent systemic RNA interference response in Leptinotarsa decemlineata larvae.
RNA interference (RNAi) is a promising approach to control Leptinotarsa decemlineata. In this study, RNAi efficiency by double-stranded RNA (dsRNA) targeting S-adenosyl-L-homocysteine hydrolase (LdSAHase) was compared among L. decemlineata first- to fourth-instar larvae. Ingesting dsLdSAHase successfully decreased the target gene expression, caused lethality, inhibited growth and impaired pupation in an instar- and concentration-dependent manner. To study the role of Dicer2 and Argonaute2 genes in RNAi efficiency, we identified LdDcr2a, LdDcr2b, LdAgo2a and LdAgo2b. Their expression levels were higher in young larvae than those in old ones. Exposure to dsegfp for 6 h significantly elevated LdDcr2a, LdDcr2b, LdAgo2a and LdAgo2b mRNA levels in the first-, second-, third- and fourth-instar larvae. When the exposure periods were extended, however, the expression levels were gradually reduced. Continuous exposure for 72 h significantly repressed the expression of LdAgo2a and LdAgo2b in the first, second and third larval instars, and the four genes in final instars. Moreover, we found that dsLdSAHase-caused LdSAHase suppressions and larval mortalities were influenced by previous dsegfp exposure: 12 h of previous exposure increased LdSAHase silencing and mortality of the final instar larvae, whereas 72 h of exposure reduced LdSAHase silencing and mortality. Thus, it seems the activities of core RNAi-machinery proteins affect RNAi efficiency in L. decemlineata.
Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China; Department of Plant Protection, Xinjiang Academy of Agricultural Sciences, Urumqi 830091, China.
Wen-Chao
WC
Guo
Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
Kai-Yun
KY
Fu
Department of Plant Protection, Xinjiang Academy of Agricultural Sciences, Urumqi 830091, China.
Shuai
S
Yang
Department of Plant Protection, Xinjiang Academy of Agricultural Sciences, Urumqi 830091, China.
Xiao-Xu
XX
Li
Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: ligq@njau.edu.cn.
Guo-Qing
GQ
Li
D043383:Adenosylhomocysteinase / Q000096:biosynthesis; D000818:Animals; D060565:Argonaute Proteins / Q000096:biosynthesis; D001517:Coleoptera / Q000235:genetics / Q000378:metabolism*; D019476:Insect Proteins / Q000096:biosynthesis; D007814:Larva; D034622:RNA Interference; D043244:Ribonuclease III / Q000096:biosynthesis
D060565:Argonaute Proteins; D019476:Insect Proteins; D043244:Ribonuclease III; D043383:Adenosylhomocysteinase
Argonaute; Dicer; Leptinotarsa decemlineata; RNA interference efficiency