Map-based Cloning And Function Analysis Of Leaf Trichome Gene In Cotton

Aerial surfaces of most land plants have epidermal trichomes.This is the adaptation mechanism of plants evolved to resist adversity.Functions of plant trichomes have been categorized as to resist insect herbivores,reduce transpiration,increase freezing tolerance,and protect plants from UV radiation.Trichomes are derived from the epidermal cells of plants,from single celled to multicellular.The molecular mechanism of trichomes of Arabidopsis is studied a lot and cotton fibers,seed trichomes,have significant economic importance.So researching the mechanisms of Arabidopsis trichome morphogenesis can reveal the mechanism of cotton fiber development to a certain extent.Two cotton species,Hai7124 with glabrous leaves and T586 with trichome were used to produce BCl population.With the help of this population,we mapped and cloned the trichome gene,then silenced the trichome gene to research it’s function by TRV-VIGS.The main research results are as follows:1.Trichome gene mapping:We investigated leaf phenotype of trichomes of BCl population in cotton seedling stage,adult stage and bud stage After the test of X2,we found the trichome phenotype separated as 1:1 which indicated the trichome gene was single gene dominant inheritance Based on the[(Hai7124×T586)×Hai7124]BCl with 666 individual plants and SSR primers,the trichome gene was mapped between S1818 and S1922,from 89.75 to 93.87 in the physical map.2.Identification of the trichome candidate gene:Five genes are chosen which has similar functions to Arabidopsisl’s genes played a role in trichome development.As the results of Q-PCR three genes expressed higher in T586 than Hai7124.The candidate gene has significant correlation between a single nucleotide polymorphisms(SNP)and leaf phenotypes of trichome in the[(Hai7124xT586)xHai7124]BCl segregating population,named GhT.3.Cloning of trichome gene GhT:The gene GhT was divided into two parts and cloned each from two cotton species,T586 and Hai7124.There are 10 exons and 9 introns in this gene and the length of DNA sequence is 3100bp and cDNA is 2178bp,encoding 725 amino acids.According to the analysis of bioinformatics,we found GhT gene belong to HD-ZIP IV family specifically expressed in plant organs of the outer cells.4.The function research of GhT gene by gene silence:TRV-derived vectors was constructed to silence the trichome gene GhT.After GhT gene silenced in T586,the number of trichomes in leaves and stems is distinctly decreased comparing to the CK.The result is similar when we chose three different trichome species cotton kept by lap to silence the trichome gene.In summary,this study mapped the trichome gene(GhT)and cloned it’s sequence.After GhT gene silenced,we found the number of trichomes is distinctly decreased in different trichome species.We showed that GhT play an important role in controlling the leaf trichome development of cotton.The results laid the foundation of breeding hairy cotton species and studying the interaction of trichome and fiber.