| Cucumber(Cucumis sativus L.,2n = 14)plays an important role in the vegetable industry in China and has high economic value.Fruit size and shape are the important quality characteristics of cucumber fruits,as well as the important agronomic traits concerned with cucumber yield.In this study,the cucumber chromosome fragment substitution lines CSSL3-7 and CSSL3-9 constructed previously in our laboratory were used for the mapping of Csfl3.2 and Csfl3.3 controlling respectively,and the candidate genes in their mapping interval were predicted and analyzed.The results are as follows:1)The phenotypic identification showed that the fruit length and fruit shape index at anthesis stage and commercial stage were both greater in CSSL3-7 and CSSL3-9compared with the recurrent parent RNS7,but the fruit transverse diameter has no difference.These data indicated that there are genes controlling cucumber fruit length in these two lines.2)Genetic analysis of BC4F2 generation plants from which CSSL3-7 and CSSL3-9 came showed that both CSSL3-7 and CSSL3-9 lines complied with Mendelian separation law of 3:1(short fruit: long fruit),indicating that the long fruit phenotype of both lines was controlled by a recessive single gene,respectively.Due to the overlapping regions(23.38Mb～29.59 Mb)of the replacement fragments of the CSSL3-7 and CSSL3-9 lines,further mapping was needed to determine whether the long-fruit phenotypes of the two lines were controlled by the same gene or by two different genes.3)After preliminary mapping,we located the QTL of CSSL3-7 between the markers m3-9and m3-10(19.05 Mb ～ 24.38 Mb);and the QTL of CSSL3-9 between the markers m3-14 and m3-15(32.63 Mb ～ 34.17 Mb).Therefore,each of CSSL3-7 and CSSL3-9 has a locus that controls the fruit shape of cucumber,and they were named Csfl3.2 and Csfl3.3,respectively.4)The microscopic results showed that,the cell volume of the fruit outer epidermis and pulp were decreased in Csfl3.2-NIL and Csfl3.3-NIL compared with the parent RNS7 and the cell number was increased.Real-time quantitative PCR analysis showed that the key genes of cytokinin signal transduction pathway in the fruits of Csfl3.2-NIL and Csfl3.3-NIL were expressed differentially,suggesting that Csfl3.2 and Csfl3.3 may increase the cell number through cytokinin,and thus lead to longer fruits of Csfl3.2-NIL and Csfl3.3-NIL.5)The soluble protein and soluble sugar contents were significantly increased in Csfl3.2-NIL and Csfl3.3-NIL compared with RNS7,indicating that Csfl3.2 and Csfl3.3also affect cucumber quality.6)Based on the gene annotations of the genes in the two members of IQD(SUN)family,CsaV3＿3G023520(Cs SUN11)and CsaV3＿3G040780(Cs SUN13),were found to be in the target region of Csfl3.2 and Csfl3.3.Sequencing results showed that there was a 57 bp deletion in the Cs SUN11 allele from RNS7.q RT-PCR results showed that the expression of Cs SUN11 and Cs SUN13 in the donor parent CNS21 with long fruit was significantly higher than that in the recurrent parent RNS7 with round fruit.Therefore,Cs SUN11 and Cs SUN13 may be the candidate genes regulating cucumber fruit length.7)In order to clarify the potential function of IQD(SUN)gene family in cucumber,genome-wide identification and analysis were conducted on the members of IQD(SUN)gene family in the cucumber genome of version 3.The results show that the cucumber version 3 genome contains 29(SUN)family members,possessing a conservative structure domain of IQ67.There are many cis-elements responsive to phytohormones and botic and abiotic stresses in the promotor region of SUN family members.Through the analysis of the published transcriptomes,some Cs SUN genes in cucumber may play important roles both in fruit growth and development and in biotic and abiotic stresses.These results provide a better understanding of the functions of Cs SUN genes in cucumber. |
PDF Full Text Request