| Osmanthus fragrans(Thunb.)Lour,belonging to Oleaceae,is the traditional ornamental scent plant native to China.Guangdong with the subtropical climate was generally considered being southern margin of Sweet Osmanthus species distribution area where the systemic investigation for Sweet Osmanthus resources was not reported so far.Therefore,It is of great significance to initiate a survey and study on the germplasm resources of Sweet Osmanthus in Guangdong for enriching the research on Sweet Osmanthus in China,creating new germplasm and promoting the effective utilization and industrial development of Sweet Osmanthus in Guangdong Province.This research combined general survey and key survey methods to conduct a investigation on the ancient Sweet Osmanthus tree resources in Guangdong,the growth index and morphological traits were measured;in addition,wild Sweet Osmanthus populations were investigated by quadrat method,and the phenotypic traits were measured.Moreover,the kinship of 53 samples were analyzed by clustering on the basis of using principal component analysis to select the important trait indicators through the trait coding method;furthermore,the characteristics of six DNA sequences of 73 samples were analyzed through amplification and sequencing,the genetic diversity of the germplasm resources were analyzed based on the cp DNA sequences,and the genetic relationship between resources were analyzed by constructing a molecular phylogenetic tree of cp DNA sequences and nuclear gene ITS based on Maximum Likelihood.The main results are as follows:Ancient Sweet Osmanthus tree resources recorded 520 trees in Guangdong were abundant in Guangdong,mainly distributed in the north of the Tropic of Cancer in this province,and preserved in Fengshui forest,temples,Taoist temples and so on.The old age of these ancient Sweet Osmanthus trees was up to 1200 a,mostly below 300 a,which had strong growth potential with large crown width,great height.The coefficient of variation of the phenotypic traits of these resources varied from 15.49% to 63.55%,and the Shannon-Wiener diversity index H’ was in the range of 1.1661 to 2.2427,which indicated that flowers and leaves of these resources were rich in variation and higher in genetic diversity.According to the flowering period,it can be classified as Group Autumn Flower and Group Four Seasons Flower,and Group Autumn Flower had the largest proportion.The colors recorded were dark yellow,golden,light yellow,yellowish white,and white.The wild species communities were found in Qingyuan city,Shaoguan city and Heyuan city in Guangdong Province,covering the latitude from 24°03′16.19″ to 25°09′56.08″.Sweet Osmanthus was habited in the evergreen broad-leaved forests or evergreen broad-leaved mixed deciduous forests of the limestone hillsides,in which Sweet Osmanthus was a species located in the middle and lower layers of the forest.The community in which Sweet Osmanthus was the dominant species was also found in the limestone hillsides of Lianzhou.The population density of surveyed communities was over1 plants/m2.The population of growth type accounted for 85.71%,and the population of stable type accounted for 14.29%.The population with androdioecious reproductive system set fruit or no fruit,the ratio of them was close to 1: 1.The renewal of those wild population were by both seed and clonal.The coefficient of variation of the phenotypic traits of wild Sweet Osmanthus varied from 13.99% to 49.30%,and the Shannon-Wiener diversity index H’was in the range of 0.3912 to 2.0348.leaf length,leaf width,petiole length,number of flowers per inflorescence,corolla diameter,pedicel length,6 traits had significant or extremely significant differences among populations.The average coefficient of variation and the average relative range of the quantitative traits of different populations was 17.45%and 41.53% respectively,which indicated that the phenotypic diversity was high.The cluster analysis results of the phenotypic traits of the leaves showed that the population had an obvious regional distribution.The leaf length and leaf width of the population showed extremely significant negative correlation and significant negative correlation with longitude,respectively,which showed that the leaves tended to become smaller from west to east.The Phenotypic quantitative classification results based on 53 samples showed that resources with the same regional source were roughly divided into one category,and the kinship of Sweet Osmanthus resources from the same area was closer.The result of genetic analysis of 73 samples based on DNA sequences of trn S-G,psb J-pet A,psb A-trn H,rpl32-trn L,ITS1,ITS2 indicated that the ratios of the variable sites and parsim-informative sites of psb J-pet A sequence were the largest,being 4.147% and 2.304% respectively.Based on the analysis of the four combined sequences of cp DNA,haplotype diversity of the wild type,ancient type,and native cultivated type of Sweet Osmanthus tree resources were respectively 0.8327,0.9167,0.9244,which showed that the genetic diversity of these resources were all high.molecular system tree clustering results based on 73 samples showed that Sweet Osmanthus resources including the wild type,ancient trees,and native cultivated type had regional differentiation phenomenon and the kinship of resources with the same regional source was closer. |
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