RAPD And SCAR Molecular Markers For Male Trait In Caric Papaya L. And Phylogenetic Analysis Of Papaya Cultivars By RAPD

Papaya, Carica papaya L., which originated in tropical America, is a polygamous diploid (2n=18) plant species with three sex types, i.e. male, female and hermaphrodite. Papaya is an excellent quality fruit in south of China. There are more 300 years since papaya was first planted in China.It speads widely in our country, especially in Guangdong, Guangxi, Fujian, Taiwan, Hainan province, and so on.The papaya is regarded as a fair source of iron and calcium; a good source of vitamins A and an excellent source of vitamin C (ascorbic acid). Papaya contains an enzyme known as papain, present in the fruit, stem and leavesThe green fruit of papaya is the source of the enzyme papain, which is used in meat tenderizers and many other biologically active phyto - chemicals. Papaya is very important not only as a food but also economically and socially due to its high acceptance on the international market.It is needed to develop papaya breeding for improved seed quality. In our country, research of papaya germ plasm resources lag in the breeding practice, It is lack of enough research to many kinds of type local resources or the ecotype in the heredity difference and the existing papaya variety heredity. The research to papaya germ plasm mainly limits to exterior shape and the agronomic characters domestic. It is short of research from the cell heredity and the molecular heredity level conducts the to the papaya existing germ plasm and the introduction germ plasm, these resons cause papaya germ plasm not to be able to used effectively and blindness in the hybrid parent match, which has affected the breeding efficiency enhancement. Because the varities of papaya mostly named by combining with the place of production and fruit characters, probably brought about synonym and homonym. The papaya usually uses the grown directly from seed reproduction, thus in grows seedlings in the process to appear some male plants, It creates waste during produces. Moreover, if we remain plants in papaya orchard with male plants could cause the seedling which later will reproduced to appear massive male plants. 6～8 months later, the papaya would enter blossom the fruiting period ,only in this period can accurate judgment of adult plant sex from the shape be got to and can we root out male plants.According to the above-mentioned some mainly questions, the experiment was carried out by RAPD and SCAR technology. Materials used for this experiment were 17 papaya cultivars, the genetic diversity and the sex diagnostic of papaya were analyzed. This experiment provides a technological basis for future molecular studies in breeding and sex diagnostic of papay. The main results were as follows:In this experiment, 16 primers were selected from 214 random primers and could be successfully used for amplifying the DNA of 17 papaya cultivars and showing polymorphism. 120 bands were obtained, among which 77 bands were polymorphic, amounting to 64.17%. Each polymorphic primer can amply 7 bands on average with rang from 5 to 10 bands. The lenth of most amplified fragment ranged from 180 to 1800bp. According to the RAPD data, the dendrogram obtained with unweighted pair group method of averages (UPGMA) showed genetic distance ranging from 0.05 to 0.23 among all style accessions, and four clusters were defined at 0.17 genetic distance. Xiangfei and Taiguohongrou papaya as a group respectively, Zhongcun No.3, Zhongcun No.l,Tainong No.5 and Xialan as a group. The largest group included the other 11 species as follows: Suizhonghong, Hongfei, Hongling, Sunrise, Tainong No.2, Lingnanzhong-GY, Meizhonghong, Xinshiji, Hongmi, Xiangmi. It is feasible to evaluated papaya germ plasm by using RAPD technique.The random amplified polymorphic DNA (RAPD) and SCAR techniques were used to determine the male trait of Carica papaya L. . 214 10-mer primers were tested. A male-associated fragment with a lenth of about 1 kb was generated with Z18 primer. The marker fragment, named Z18-1000 exists in all male plants but not in the female and hermaphrodite plants so far analyzed. The fragment was cloned and sequenced. The results showed that this marker consisted of 1001 bp with specific nucleotide sequence. The sequence data have been submitted to GenBank. The GenBank accession number was DQ787854. Four primers were designed based on the sequence to transform RAPD marker into SCAR marker. The RAPD marker was successfully converted into a SCAR marker, which was designated SD1000.