Study On The Exogenous GABA Inducing Tomato SlBAT1s Gene Expression And Key Technology Of Improving Fruit Quality

Tomato(Solanum lycopersicum L.)is the main vegetable crop in protected cultivation.The improvement of fruit quality has become a research hotspot in recent years,and it is also an important content of high-quality development of protected vegetables.γAminobutyric acid(GABA)is a non protein amino acid,which plays a key role in the metabolism of organic acids and amino acids in tomato fruit,However,there are few studies on the regulation of the key genes SlBAT1 and GABA as exogenous substances on tomato fruit growth and quality.Therefore,in this experiment,tomato’Dongsheng T06’was used as material.and the flowers were treated with exogenous GABA.On the basis of detecting the expression changes of slbatl and key genes of metabolic pathway in flowers.SlBAT1s gene was cloned and analyzed by bioinformatics;The effects of different concentrations of GABA,treatment times and treatment time on the quality of tomato fruit were studied.Through the determination of growth and quality indexes,the suitable GABA treatment methods were selected to improve the quality of tomato fruit and provide theoretical basis and practical reference for GABA to improve the quality of tomato.The main results are as follows:(1)The difference of key gene expression in the transport and metabolism pathway of GABA across mitochondrial membrane was as SlBAT1s>SlGABA-Ts>SlGADs>SlSSADH,which proved that slbatl s played an important role in the regulation of GABA metabolism.On this basis,three transcriptional genes SlBAT1-X1,SlBAT1-X2 and SIBAT1-X3 were cloned.encoding 534,515 and 428 amino acids,respectively.Phylogenetic analysis showed that the similarity between SlBAT1-X1 and tobacco was 88.35%,and that between SlBAT1-X2 and SlBAT1-X3 was 93.15%;SlBAT1-X1 and SlBAT1-X2 proteins have 12 transmembrane helices,and SlBAT1-X3 protein has 9 transmembrane helices.(2)Different concentrations of GABA(0,10,20,30 mM)could promote the growth and quality of tomato fruit.Compared with other treatments,20 mM had higher effects on the transverse and longitudinal diameter,single fruit weight,soluble protein,vitamin C.malic acid,malonic acid,citric acid.glutamic acid,serine and lysine of tomato fruit.The results showed that 20 mM exogenous GABA treatment was suitable for tomato fruit growth and quality improvement.(3)The effects of 20 mM GABA treatment times(1,2,4 times)on tomato fruit growth and quality were significantly different.Compared with the control,the fruit transverse diameter,single fruit weight,soluble protein and alanine content were significantly increased by different GABA treatments.The fruit longitudinal diameter,citric acid,endogenous GABA,isoleucine and leucine content were significantly increased by one treatment,which were significantly higher than those of the control,two and four treatments.The results showed that the cumulative effect of GABA treatment was not obvious,and the growth and quality index of tomato fruit could be improved after one treatment.(4)After 20 mM GABA treatment at flowering stage and young fruit stage,the growth and quality indexes of tomato fruit first increased and then decreased.After 15 days of treatment,the fruit growth and the contents of soluble solids,soluble sugar,soluble protein,vitamin C,malic acid,citric acid and amino acids were significantly higher than those of the control;However,the increase of other indexes and the ratio of sugar to acid reached the maximum at 30 days of flowering stage,except for organic acids,while the increase was lower than 15 days at young fruit stage;Both treatments showed a downward trend at 45days and 60 days,and there was little difference at 60 days compared with the control.The results showed that exogenous GABA had the best effect on the growth and quality of tomato fruit at 15～30 days after flowering and 15 days after young fruit stage.(5)The effect of applying 20 mM GABA at different time before harvest on tomato fruit quality was obvious.The contents of soluble solids,soluble sugar,soluble protein.vitamin C,lycopene,organic acid,sugar acid ratio and amino acid in the treatment of 3 days and 6 days before harvest were significantly higher than those in the control,and the treatment of 6 days had the greatest increase in lycopene,vitamin C,malic acid and citric acid.However,with the extension of treatment time,the improvement of fruit quality gradually decreased.There was no significant difference in soluble protein,vitamin C.malic acid and alanine between 9 days and 12 days treatment and the control.Lycopene.oxalic acid,aspartic acid,glutamic acid and endogenous GABA were significantly higher than those of the control at 15 days,but other indicators had little difference compared with the control.The results showed that 20 mM GABA treatment could improve the quality of tomato fruit 6 days before harvest.