The Function Of Carotenoid Biosynthesis Genes In The Two-spotted Spider Mite

Carotenoids are conjugated isoprenoid organic pigments,which have several of species and diverse structures in nature.Carotenoids play a serious of roles in organisms,including protection of cell membrane,photosynthesis,photo-oxidation protection,diapause,vision,immunity,biological regulation and so on.Previous study has demonstrated that carotenoids generally are self-biosynthesized in plants,argaes,bacteria and funguses,but animals can only acquire carotenoids by feeding not by self-biosynthesis.Following the discovery of the aphids’ genome,researchers found carotenoid biosynthesis genes transferred from fungi in aphids’ genome,and they also confirmed the participation of these genes into the regulation of color change in aphids.Recently,study also find carotenoid biosynthesis genes in two spotted mites and gall midges,and the study demonstrated the closely relationship with funguses.So the research of the function of the transferred carotenoid biosynthesis genes in animals will make researchers to overview the origin of the carotenoids in animals,especially in arthropods,who achieve carotenoids only from diets.The two spotted spider mite is one of the most important agricultural pests,recent studies and our sequencing of the two spotted spider mites both find that the mRNA levels of carotenoid biosynthesis genes have a relationship with diapause.Our research will study the gene function from here.As we know,RNA interference is a new developmental scientific research method which has been widely and effectively applied into the study of the gene function.This use of the technology,which not only used for the study of gene function,but also provides a new effective methods for the study of the two spotted spider mites.In this study,the two-spotted spider mite has green and red strains which have a similar genetic background,so we firstly cloned these carotenoid biosynthesis genes in both two strains in the two spotted spider mite.A recent study has found that in the orange red diapause mites and red strain mites,PsLc(260)and Pds(270)two genes have a significantly increased mRNA levels in green strain statement than these red mites,so the full length of these two genes showed that there is a sequence identity up to 99%in the protein sequence,and the structure and the function domain is consistent.And then we chose the mites undergoing color change as research materials to study the dynamic expression of 6 carotenoid biosynthesis genes.The results showed that,the expression of the two genes increased along with the age changing conditions in the diapause spider mites,and both two genes’ expression model are basically the same,which means they have the highest mRNA levels in the diapause adults at the age of 3,down regulation of the overall trend in body color change stage after this increase.The down regulated genes along with the age growth showed a trend of decreased expression in diapause mites,and then down-regulated which show that they are probably not participate in the regulation of diapause process.In this study,we are trying to interference the high expressed genes in diapause to verify these functions.As RNA interference is a new method to gene research in two spotted spider mites,this study firstly established an effective RNA interference system,and successfully interference the expression of the PsLc and PDS genes in diapause mites.The results show that,after the injection of dRNA,the highest efficiency happened after the injection of 48-72h;Tne mixture or single dsRNA both can inhibit the expression of two genes in an extant,and lead to the change of the two spotted spider mites’ phenotype,which has significant influence the color change.Meanwhile,the total carotenoid contents are partly inhibited.These results validate the relationship between the carotenoid synthesis genes and color change.And the results confirmed the relationship between the contents of pigments and color change.These results provide ideas and directions to other researches in carotenoid biosynthesis process and others.Finally,it is the first time to study the carotenoid biosynthesis pathway by the upstream pathway’s regulation in transcript levels.The results demonstrated that IPP synthesis and FPP branching process is consistent with the increasing results of biosynthesis process red strains to green.The results also show that a part of Tc FPP shunting for the synthesis of juvenile hormone,and parts for the synthesis of GGPP which is a substrate of carotenoid biosynthesis.