Analysis Of GAD Polymorphism In Chenopodium Quinoa And Gene Mapping Of A Dewarf Mutant Of Arabidopsis Thaliana

Gamma-aminobutyric acid（GABA）is a ubiquitous four-carbon nonprotein amino acid found in eukaryotes and prokaryotes.In mammalian,GABA is the major inhibitory neurotransmitter in the central nervours system.Until now,GABA in plant is not only a metabolite,but a signal molecule.Its function is versatile including responding to abiotic and biotic stress,maintaining C/N balance,involving in plant development.Glutamate decarboxylase（GAD）is a pyridoxal 5’-phosphate（PLP）-dependent enzyme in cytosol.GAD is the key step-limting enzyme and catalyzes the irreversible decarboxylation reaction from L-glutamate to GABA.GAD activity is related with the GABA content.The polymorphism of functional gene is important in metabolism of secondarymetabolites.In this study,weanalyze the gene polymorphism of Cq GAD and try to clarify the relation of Cq GAD polymorphism and GABA content.Firstly,we analyzed the genome sequence of Chenopodium quinoa.There were eight genes encoding GAD in quinoa genom.Then the polymorphism of AUR62038577 was analyzed in 796 quinoa species through this SSR marker and the quinoa species were fell into the different groups based on the type of PCR bands.Then two quinoa species were selected from one group and the GABA content of them was determined by automatic amino acid analyzer.Finally,the c DNAs of Cq GAD of four species（two of them have the highest GABA content and two have the lowest GABA content）were cloned by RT-PCR and analyze the relation of GABA content and c DNA sequence variation.Besides the study of GAD polymorphism,the phenotype of a dewarf mutant of Arabidopsis thaliana was identified.This mutant is a T-DNA insertion mutant and was backcrossed with the wild type Ws for three times.Because the T-DNA losed in this mutant,so we obtained the mutant site by map position.The mutated gene was lacated in the region of18.42M bp and 18.79M bp on the 2^nd chromasome of Arabidopsis.Then the mutant was re-sequenced and some sites of In Del or SV was found in this region and verified one by one.