| Bananas are the most abundantly produced fruit varieties in the tropical areas of China. It belongs to the genus Musa (family Musaceae), and the "banana" is a generic term for edible bananas. The Chinese banana, also known as Cavendish, is triploid varieties evolved from natural hybrid breeding in M. acuminate. Although the pedigree of hybrid variety is well defined the Cavendish breed has several different names, which pose confusion and obstacle to the development and production of this species.In recent years, the RAPD molecular marker technology has been widely used in molecular breeding and the analysis of the diversity of banana. However, the disadvantages of using the RAPD molecular marker include poor reproducibility and low stability, which, to a certain extent, lead to unreliability of the analysis results. The SCAR molecular marker technology, developed based on the RAPD marker, overcomes the drawback of RAPD markers while retaining the good features of RAPD marker. It has been successfully applied in the study of different varieties of rice, tea and other crops, but there is no similar research report about the variety differentiation and diversity analysis in Cavendish varieties of banana.By using RAPD-SCAR molecular marker technologies for the study of36Cavendish varieties from the Banana Germplasm Resources Garden and Banana Germplasm Resources Garden of TCGRI of CATAS and4test varieties, this paper aims to distinguish, classify Cavendish varieties and provide basis for its accurate naming. In the first place, the genetic diversity among40Cavendish varieties was studied by using RAPD molecular marker. In the second place, the sequencing analysis of differential DNA fragments was conducted. According to sequencing results of the differential DNA fragments, the design of corresponding SCAR primers was inward stretched out10bp oligonucleotides on the basis of the original RAPD primers. Then the verification was initated to determine whether amplifying a single band with the difference was possible, based on using SCAR primers for PCR amplification and the genomic DNA of the40Cavendish varieties as templates. Lastly, the combined use of SCAR markers of different Cavendish varieties would lead to the development of a rapid identification protocol for40Cavendish varieties. The major results are summarized as follows:(1) The RAPD-PCR among40Cavendish varieties was amplified by using RAPD primers. Six RAPD primers that could stably amplify differential DNA fragments were selected:A15, B04, B06, B13, B17, B20, SS262. A15could stably amplified2differential DNA fragments. A total of8differential DNA fragments were obtained. Their lengths were respectively,416bp,664bp,781bp,481bp,1057bp,410bp,694bp, and1053bp, with no higher homology sequence after analysis.(2) According to DNA sequences of the8differential DNA fragments, corresponding SCAR primers were designed and8successful SCAR markers were converted.(3) The combined use of8SCAR markers enabled the recognition of14cultivars in 40Cavendish varieties:Nong Ke No.1, Tai Jiao3Hao, Tai Jiao4Hao, Nan Tian Hong, Kang Ku No.5, Tian Bao Zhong Ba, Hai Jiao No.1, Qing Gan Ba Xi, EPI, He Kou Zhong Ba, Chang Guo Ba Xi, Tian Bao Jiao, Long You, and Long Xuan. In addition,26cultivars were classified into3distinct groups:the first group including Ba Xi, Bei Jiao, Xin Bei Jiao, Nan Tian Huang, Kang Ku No.1, and Bao Dao Jiao; the second group including Ba Xi Huang Zhong, and Guang Xi Ai Jiao and the third group including Wiliams8818, Wiliams B6, Hai Nan Tai Wan Jiao, Hai Nan Tai Guo Jiao, Guang Dong No.1, Guang Dong No.2, Zhong Jiao Qing Ya Jiao, Da Zhong Gao Ba, Da Zhong Gao Ba Gao, Williams (big), He Kou Ai Jiao, Hong He Ai Jiao, Jian Feng Ling Ai Jiao, Dong Guan Zhong Ba, Ai Jiao Dun Di Lei, Gao Jiao Dun Di Lei, Zhang Xuan Yi Hao, and Zhang Xuan Er Hao. |
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