Cloning And Functional Exploration Of The Key Gene Tra2 For Sex Determination In Bradysia Odoriphaga

Bradysia odoriphaga is a native root maggot in China.At present,most of the prevention and control methods of B.odoriphaga are chemical control.Unscientific drug use not only increases insect resistance,but also easily leads to human and animal poisoning and environmental pollution.Therefore,it is very important to find a green,safe and environmental protection method for the prevention and control of B.odoriphaga.In breeding,we found that the majority of B.odoriphaga were mono-sex offspring,while the number of bi-sex offspring was minority.The mechanism of sex determination and its application value aroused our interest.In this study,Botra2,a key sex determining gene,and its application were studied.The main conclusions are as follows:1.The Botra2 gene was isolated and identified,and two Botra2 transcripts were obtained,both of which were gender nonspecific splicer.2.Botra2 gene was expressed in the whole growth and development stage(egg,larva,pupa,adult)of Bradysia odoriphaga,and was highly expressed in pupal stage and adult stage.The expression level increased sharply from the fourth instar larva to the pupal stage,and the expression level of female adult was higher than that of male adult.3.After silencing the Botra2 gene of B.odoriphaga,the expression of Botra2 in both males and females was significantly down-regulated,and the expression of Botra2 in females was better inhibited.4.After RNA interference,the internal genitalia and external morphometry as well as the number of eggs laid by the female and the hatching rate of the offspring were measured.It was found that the ovary was somewhat shortened and showed some defect features,such as smaller than usual,scattered and irregular eggs.The body length and wing length of females increased significantly,whereas the body length and wing length of males were significantly shortened,and their external genitalia were reduced to a certain extent.The oviposition of single females and the oviposition of offspring decreased significantly.The results preliminarily confirmed the function of the Botra2 gene,and provided a research basis for the prevention and control of insect pests.