GLUTATHIONE S‐TRANSFERASE Genes IN THE RICE LEAFFOLDER, Cnaphalocrocis medinalis (LEPIDOPTERA: PYRALIDAE): IDENTIFICATION AND EXPRESSION PROFILES

Abstract

In insects, glutathione S-transferases (GSTs) play critical roles in the detoxification of various insecticides, resulting in insecticide resistance. The rice leaffolder, Cnaphalocrocis medinalis, is an economically important pest of rice in Asia. GST genes have not been largely identified in this insect species. In the present study, by searching the transcriptome dataset, 25 candidate GST genes were identified in C. medinalis for the first time. Of these, 23 predicted GST proteins fell into five cytosolic classes (delta, epsilon, omega, sigma, and zeta), and two were assigned to the "unclassified" subgroup. Real-time quantitative PCR analysis showed that these GST genes were differentially expressed in various tissues, including the midgut, Malpighian tubules, and fat body of larvae, and the antenna, abdomen, and leg of adults, indicating diversified functions for these genes. Transcription levels of CmGSTd2, CmGSTe6, and CmGSTe7 increased significantly in larvae following exposure to chlorpyrifos, suggesting that these GST genes could be involved in the detoxification of this insecticide. The results of our study pave the way to a better understanding of the detoxification system of C. medinalis.

Functional characterization of a novel λ‐cyhalothrin metabolizing glutathione S‐transferase, CpGSTe3, from the codling moth Cydia pomonella

“…In B. dorsalis , the expressions of multiple GST genes were increased by β‐cypermethrin, suggesting that the GST gene may function in detoxifying β‐cypermethrin . In contrast, the mRNA transcript of the remaining GST gene CpGSTe1 was decreased after treatment with a LD 10 of λ ‐cyhalothrin for 3–12 h. Down‐regulated expression of GST genes has been also reported in P. xylostella , N. lugens , C. medinalis , and L. decemlineata after exposure to insecticides . Down‐regulation of a subset of GSTs may be an adaptive mechanism in insects for reducing the total enzymatic activity of GST enzymes to prevent exhausting the supply of GSH .…”

“…35 In contrast, the mRNA transcript of the remaining GST gene CpGSTe1 was decreased after treatment with a LD 10 of -cyhalothrin for 3-12 h. Down-regulated expression of GST genes has been also reported in P. xylostella, N. lugens, C. medinalis, and L. decemlineata after exposure to insecticides. [41][42][43][44] Down-regulation of a subset of GSTs may be an adaptive mechanism in insects for reducing the total enzymatic activity of GST enzymes to prevent exhausting the supply of GSH. 44 These results indicate that these up-regulated GST genes may be involved in detoxification of -cyhalothrin in C. pomonella.…”

Glutathione-S-Transferases in the Olfactory Organ of the Noctuid Moth Spodoptera littoralis, Diversity and Conservation of Chemosensory Clades

“…To test whether this characteristic was shared with the other members of the subclade, we first searched for SP in the sequence of AtraGST (Leal et al, 2009), MsexGST-msolf (Robertson et al, 1999; Rogers et al, 1999), CsupGSTd1 (Liu et al, 2015a) and CmedGSTd1 (Liu et al, 2015b) and we indeed identified putative SPs for all them. We then completed by bioinformatics the N-terminus sequences for the 5 other genes from this clade ( SfruGSTd2, HarmGSTd02, BmGSTd1, EposGST11 , and PxylGSTd1 ) and we also identified predicted SP for each of them.…”

“…In S. littoralis , epsilon clade accounts for almost half of the described sequences, with various expression patterns ranging from ubiquitous to antennal enriched genes. SlitGSTe clustered with lepidopteran GSTe functionally involved in insecticide conjugation and protection against oxidative stress in B. mori, H. armigera, S. litura , and S. exigua (Huang et al, 2011; Yamamoto et al, 2013; Liu et al, 2015b; Xu et al, 2015; You et al, 2015; Zhou et al, 2015; Wan et al, 2016; Zhang et al, 2016; Hirowatari et al, 2017; Labade et al, 2018). Moreover, three P. xylostella GSTe are also preferentially expressed in the antennae (He et al, 2017), suggesting a potential role in olfaction.…”

“…However, the expression of GSTs as well as their activities have been also highlighted in the olfactory organs of several insect species. Antennal expressed GSTs have been indeed identified in various moth species, such as Manduca sexta (Rogers et al, 1999), Helicoverpa armigera (Wang et al, 2004), Amyelois transitella (Leal et al, 2009), Bombyx mori (Tan et al, 2014), Chilo suppressalis (Liu et al, 2015a), Epiphyas postvittana (Corcoran et al, 2015), Cnaphalocris medinalis (Liu et al, 2015b), and Cydia pomonella (Huang et al, 2017), but also in the fruit fly Drosophila melanogaster (Younus et al, 2014) or in the beetles Agrilus planipennis (Mamidala et al, 2013), Dendroctonus valens (Gu et al, 2015), and Phyllotreta striolata (Wu et al, 2016). This particular localization led to the hypothesis of a possible dual function of GSTs in antennae where, besides their original implication in xenobiotic metabolism, they could play a role in the signal termination and in odorant clearance, as Odorant-Degrading Enzymes (ODEs, Vogt and Riddiford, 1981; Chertemps, 2017).…”