Abstract: 【Aim】 The objective of this study is to clone phospholipid hydroperoxide glutathione peroxidase (PHGPX) genes from Bemisia tabaci MEAM1 cryptic species, to identify their expression levels in whiteflies at different developmental stages and in female adults treated with imidacloprid for different time, and to elucidate their function in the whitefly in response to environmental pressure. 【Methods】 The cDNAs of PHGPX genes were cloned by 3′RACE from B. tabaci MEAM1 cryptic species, and the putative amino acid sequences were analyzed by bioinformatics methods. The expression levels of PHGPX genes in the whitefly at different developmental stages and in female adults treated with imidacloprid for different time were analyzed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). 【Results】 The full-length cDNA sequences of two PHGPX genes were obtained from B. tabaci MEAM1 cryptic species, and named as BtB-PHGPX1 (GenBank accession no.: KY312116) and BtB-PHGPX2 (GenBank accession no.: KY312117), respectively. Sequence analysis indicated that the open reading frame of BtB-PHGPX1 is 732 bp in length encoding 243 amino acids, while that of BtB-PHGPX2 is 567 bp in length encoding 188 amino acids. Sequence alignment result showed that the encoded proteins of both genes have conserved cysteine, glutamine and tryptophan residues of glutathione peroxidase. The mRNA level of BtB-PHGPX1 in egg was significant higher than those in nymph, pseudopupa, female adult and male adult of the whitefly, while that of BtB-PHGPX2 in egg was significant lower than those in nymph, pseudopupa and female adult (P<0.05). The mRNA levels of both BtB-PHGPX1 and BtB-PHGPX2 in female adults were significant higher than those in male adults (P<0.05). Furthermore, the expression levels of BtB-PHGPX1 and BtB-PHGPX2 significantly increased in female adults at 2 h after treatment with imidacloprid as compared with their respective control (P<0.05), but decreased significantly at 5, 10 and 24 h after treatment (P<0.01). 【Conclusion】 In this study, the full-length sequences of two PHGPX genes were cloned from B. tabaci MEAM1 cryptic species, and their differential expression at different developmental stages and in female adults treated with imidacloprid for different time was clarified. It is speculated that PHGPX may play an important defense role in B. tabaci under environmental stress and insecticide treatment.

Key words: Bemisia tabaci, MEAM1 cryptic species, phospholipid hydroperoxide glutathione peroxidase, oxidative stress, imidacloprid