Abstract: Integrin are transmembrane heterodimers composed of α and β subunits, playing an important role in regulating cell proliferation. This study investigates how integrin β functions during embryonic proliferation in Macrocentrus cingulum. Mcitg-β (GenBank accession no. KC784942) was successfully cloned by PCR. It has an open reading frame of 2 526 bp, encodes an 841 amino-residual protein, and contains typical function domains of integrin genes. Alignment results showed that Mcitg-β is a member of insect integrin gene family, and phylogenetic analysis showed that it shares the highest nucleotide sequence identity (up to 76%) with the integrin gene from Bombus impatiens.  qRT-PCR results revealed that Mcitg-β was expressed in primary embryos and secondary embryos, especially highly in eggs, but none in morulae. After RNA interference with dsMcitg-β or siMcitg-β in culture medium, the expression of Mcitg-β mRNA and proliferation ability of embryos were decreased. Furthermore, injecting dsMcitg-β into the parasitized larvae of host Ostrinia furncalis decreased the number of wasp’s offsprings in each host larva. These results initially prove that Mcitg-β may play important roles in regulating the proliferation of embryos in M. cingulum.

Key words: Macrocentrus cingulum, integrin &beta, subunit, gene cloning, RNA interference (RNAi), embryonic proliferation