干扰LYC-B基因调控番茄果实挥发性物质及主要品质性状

Down-Regulated Expression of LYC-B Gene by RNA Interference Regulates the Volatiles and Main Quality Traits of Tomato Fruits

构建含有番茄红素β-环化酶(lycopeneβ-cyclase,LYC-B)基因LYC-B中801 bp和301 bp两段保守序列的RNA干扰植物表达载体,农杆菌果实注射法遗传转化紫色番茄果实,通过卡那霉素抗性筛选、聚合酶链式反应及LYC-B基因表达量鉴定获得转基因植株,并对转基因植株成熟果实的挥发性物质及主要品质性状进行测定。结果表明,干扰LYC-B基因后番茄果实中检测到的挥发性物质主要为醇类、醛类、酮类、酯类和其他类。与野生型相比,转基因植株中总挥发性物质种类增加了6种:醛类3种、酮类2种、酯类1种;醇类个数不变;其他类减少1种。醛类物质相对含量不变,醇类物质相对含量减少,酮类、酯类和其他类相对含量增加。特征挥发性物质反-2-庚烯醛、6-甲基-5-庚烯-2-酮、水杨酸甲酯和2-异丁基噻唑等的相对含量增加。番茄红素的含量增加了16.78%,可溶性固形物、抗坏血酸和总酸等含量增加,β-胡萝卜素和总糖含量变化显著。干扰LYC-B基因不仅影响了番茄果实的挥发性物质,还增加了番茄红素、可溶性固形物、抗坏血酸、总酸等的含量。

This work aimed to regulate the volatile components and major quality traits of tomato fruits by down-regulation of the expression of lycopene β-cyclase（LYC-B） gene using antisense RNA interference technique.Purple tomato fruits were transformed by injection of the plant expression vector containing two conserved sequences（801 and 301 bp,respectively）of LYC-B gene.The transgenic plants were obtained kanamycin resistance screening,polymerase chain reaction and quantification of LYC-B gene expression.The volatile substances and major quality traits of ripe tomato fruits were compared between the transgenic and wild-type（WT） plants.The results showed that alcohols,aldehydes,ketones,esters and other volatiles were detected in transgenic tomato fruits.Compared with the wild-type control,six new volatile compounds were identified from the transgenic fruits,consisting of three aldehydes,two ketones,and one ester,and one compound belonging to another chemical class was detected in the control rather than the transgenic fruits.In addition,the same relative content of aldehydes was observed between both fruits,but the transgenic fruits showed decreased relative content of alcohols and increased relative contents of ketones,esters and other compounds.The characteristic volatile compounds were also increased,such as（E） 2-heptenal,6-methyl 5-hepten-2-one,methyl salicylate and 2-isobutylthiazole,and lycopene increase by 16.78%compared with the wild-type fruits.In addition,the contents of soluble solids,ascorbic acid and total acid were also increased.On the other hand,the contents of β-carotene and total sugar were identical to those of the WT fruits.Therefore,down-regulated expression of LYC-B gene by RNA interference can affect volatile substances and enhance the contents of lycopene,soluble solids,ascorbic acid and total acid,thereby improving the nutritional quality of tomato fruits.