Identification,fruit length variation and molecular mechanism of Cucumis sativus-C.hystrix alien addition lines
[Objectives]The paper aimed to explore the molecular mechanism of cucumber fruit shortening caused by the introduction of Cucumis hystrix chromosome 6 in alien addition lines(AAL)by analyzing the fruit differences of different C.sativus-C.hystrix A AL,so as to provide theoretical basis for excellent character mining and utilization of cucumber related wild species.[Methods]Molecular markers and Oligo-FISH were used to identify the alien chromosomes in C.sativus-C.hystrix AAL.The fruit traits of cultivated cucumber'Beijingjietou'(CC3)and different C.sativus-C.hystrix AAL were statistically analyzed,paraffin sections and transcriptome sequencing were carried out,and the results of transcriptome sequencing were verified by real-time fluorescence quantitative PCR(RT-qPCR).[Results]A total of 7 different AAL were identified,including monosomic alien additive lines with the C.hystrix chromosome 6(CC-H06),chromosome 8(CC-H08),chromosome 9(CC-H09)and chromosome 10(CC-H10);double monosomic alien additive lines with the C.hystrix chromosomes 6 and 10(CC-H06+H10);and multiple monosomic alien additional lines with the C.hystrix chromosomes 6,7 and 11(CC-H06+H07+H11)and the C.hystrix chromosomes 6,7,10,11,and 12(CC-H06+H07+H10+H11+H12),respectively.Phenotypic investigation showed that the ovary and fruit length of AAL CC-H08,CC-H09 and CC-H10 were all similar to that of CC3,while CC-H06 was significantly shorter than that of CC3,indicating that the introduction of C.hystrix chromosome 6 would lead to the fruit shortening of CC3.The results of paraffin section showed that the fruit cells of CC-H06 were larger than those of CC3,but the number of cells was significantly reduced.Transcriptomic analysis showed that there were 695 and 2 770 differentially expressed genes derived from C.hystrix and CC3 in CC-H06,respectively,which were mainly concentrated in plant hormone signal transduction,zeatin biosynthesis,diterpenoid biosynthesis,tryptophan metabolism and other hormone synthesis pathways.The results of RT-qPCR verification analysis were consistent with those of transcriptome determination,which showed that the results were true and reliable.[Conclusions]The introduction of C.hystrix chromosome 6 could cause the shortening of fruit and the decrease of fruit cell number in CC3.The fruit shortening of CC-H06 was related to the co-regulation of plant hormones such as auxin,cytokinin and gibberellin.