Transcriptomic Analysis Preliminarily Revealed The Molecular Mechanism Of Fruit Variation Of Short Fruit 1 In Cucumber

Fruit length is a highly valuable external quality trait in cucumber(Cucumis sativus L.).The short fruit 1(sf1)mutant is a natural mutant with short fruit and other changed fruit characteristics,which was isolated from ‘Nongcheng 2' inbred line and controlled by a recessive gene,so sf1 is a good material for studying the appearance and inner quality of cucumber fruits.More variations of sf1 compared with wild type(WT)were discovered in this study: bigger stigma,longer spine and larger seed cavity.In order to understand the molecular mechanism of the appearance and inner quality of cucumber fruit,the fruits at 9 days after anthesis from sf1 and non-mutation of F2 were used for transcriptomic analysis,respectively.478 genes were found to be differentially expressed,among which 200 genes were significantly up-regulated and 278 down-regulated in sf1 compared with WT.For these differentially expressed genes(DEGs),the most significantly enriched GO terms were metabolic process and cellular process in the biological process group,and catalytic activity and binding in the molecular function group.The key genes in the pathways of auxin and cytokinin signal transduction and gibberellins biosynthesis were differentially expressed,and the contents of auxin,cytokinin and gibberellins were changed accordingly,which were consistent with the larger cell size and less cell number of sf1 fruits.Some DEGs encode the key enzymes in the pathway of lignin biosynthesis,which were consistent with higher content of lignin in sf1 fruits.The differential expression of the key genes involved in carotenoid biosynthesis should be the cause of lower content of carotenoid in pericarp of sf1 fruits.In addition,to understand the function of the two MADS-box genes from DEGs,they were transformed into tomato,but the transgenic lines have no obvious variation.In conclusion,the molecular base of the important traits of sf1 fruit affected by sf1 was preliminarily revealed,which offered a theoretical basis for sf1 cloning and functional studying of sf1.