| Onion (Allium cepa L.) is the worldwide vegetable cultivars. Chinese Onion production area and yield are leap into the front ranks of the world. In recent years, the rapid development of molecular biological techniques, with the accurate, rapid, widely used and reproducible features, are especially suitable for new varieties breeding of long growth cycle crop, such as onion. In order to speed up the process of onion breeding and to improve the efficiency of breeding, not only morphological indexes of37onions germplasm resources were surveyed, but also RAPD and SSR markers were used to detect genetic diversity and to analyze cluster. The results were presented as below:1. Through the survey of15morphological characters of37onion germplasm resources, we found that each of morphological index showed significant genetic differences between various germplasm. There was abundant genetic variation in stem color and skin color, which can be used as a trait in breeding improved.2. Six morphological indicators associated with the above-ground and below-ground were selected to conduct correlation analysis. We found significant positive correlation between plant height and number of leaves, plant height and bulb skin color, plant height and weight of a single ball, plant height and bulb layers, Leaf number and weight of a single ball, Leaf number and bulb layers, Leaf number and bulb skin color, weight of a single ball and the bulb layer.3. Through the principal component analysis of each morphological indicator for onion, the15morphological indicators were divided into three main components, whose cumulative contribution rate was71.9%. It could basically reflect the relationship of different quantitative character between germplasm resources. Calculating the comprehensive scores of three main components, we found that two germplasm with the highest score were the3#(Xi An Hong Pi) and26#(63) varieties, whose color were red and the bulb shapes were high-round and round-sphere respectively. With Euclidean distance of18.5as the clustering threshold, the37onion germplasm resources were divided into two categories, which could be further sub-divided into five groups. 4. The genetic diversity of37onions germplasm resources were analyzed by SSR and RAPD markers and the results of two markers were compared. The results showed that61polymorphic bands were detected by15RAPD primers and41polymorphic bands were detected by8pairs of SSR primer. Both RAPD and SSR were highly polymorphic. The percentage of polymorphic RAPD bands was84.7%. The average effective number of alleles was3.75for SSR. The average effective number of alleles, Nei’s genetic diversity index, Shannon information index for SSR markers were higher than RAPD.5. UPGMA cluster analysis indicated that both RAPD and SSR markers could divide the37germplasm into four groups and the cluster analysis result was similar. Four pairs of male sterile line and maintainer line, including32#(11,43-④A) and33#(11,43-④B),36#(8,43A) and37#(8,43B),38#(8,11,43x59-①A)and39#(8,11,43×59-①B),40#(8,43,57A)and41#(8,43,57B), were grouped together;9#(Di Qiu),28#(64) and29#(66) were clustered into one section, which were medium high-yield varieties;2#(2012-2),4#(Sheng Hong Gao Zhuang),5#(2012-4-4),21#(Mu Tong) and23#(Chuan Tian Da Bao) were clustered into one section, which were late high-yield varieties.6. The similarity that Clustering results of morphological and two kinds of molecular markers (RAPD and SSR) could clustered8#(Tian Hui Da Huang Bao),10#(Jin Bao),11#(Zi Yang Hong Bao),12#(Chuan Tian Chi Da Yu),13#(Qi Yu Zao Sheng),14#(Huang Jin Da Yu Cong),15#(Tian Hui Jin Huang Guan),16#(Feng Bao),19#(Zhong Nong Hong Deng Long) and20#(Zhong Nong Ju Feng) into one section, which were prematurity low-yield varieties. |
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