AUTHOR=Ma Long , Zhang Wanna , Liu Chen , Chen Lin , Xu Yang , Xiao Haijun , Liang Gemei 

TITLE=Methoprene-Tolerant (Met) Is Indispensable for Larval Metamorphosis and Female Reproduction in the Cotton Bollworm Helicoverpa armigera

JOURNAL=Frontiers in Physiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2018.01601

DOI=10.3389/fphys.2018.01601

ISSN=1664-042X

ABSTRACT=<p>Juvenile hormone (JH) represses larval metamorphosis and induces adult reproduction in insects. Methoprene-tolerant (Met) is identified as an intranuclear receptor that mediates JH actions. In the present study, we characterized a Met from the severe agricultural pest, <italic>Helicoverpa armigera</italic>, namely HaMet. In the larval stage, <italic>HaMet</italic> is predominantly expressed in the epidermis and midgut, and is upregulated before each molting, whereas in adults <italic>HaMet</italic> is maximally expressed in the ovary, testis, and fat body. The immunofluorescence assay revealed that HaMet was distributed in the longitudinal and circular muscle layers of midgut in larvae, whereas in the ovary of female adults, HaMet was localized in the nucleus of the oolemma. Knockdown of <italic>HaMet</italic> in final-instar larvae shortened the time of pupation, induced abnormal pupation, and dampened pupation rate. In female adults, <italic>HaMet</italic> depletion severely suppressed the transcription of <italic>Vitellogenin</italic> (<italic>Vg</italic>) and <italic>Vitellogenin Receptor</italic> (<italic>VgR</italic>), disrupted the Vg accumulation in fat body and the yolk protein uptake in oocytes, and finally led to an impaired fecundity. Our findings therefore confirmed that HaMet acted as a nuclear receptor of JH and played an essential role in larval metamorphosis, vitellogenesis, and oocyte maturation.</p>