| In this paper,30 Chinese fir clones were taken as the research objects in order to investigated the difference of cones and seed characters in the 1.5 generation seed orchard at beijianghe State-owned Forest Farm,rongshui,Guangxi Province.The genetic diversity of SSR markers in Chinese fir clones was analyzed by using 17 pairs of primers for SSR molecular marker PCR amplification.The main results were as follows:(1)According to the different morphological characteristics of Chinese fir cone bract scale,it can be divided into three types:tightly wrapped,loosely wrapped,and inverted warping.The percentage of cone type ranked from big to small in the order:the loose type>the tight capsule type>the reverse warping type,being of 56.67%,33.33%,10.00%.The average seed yield was 3.56%.The average seed yield of tight-capsule type was the highest,followed by the loose type.The cone types of the same clone are basically the same,but there are two or more cone types in a few clones.There are obvious phenomena of on and off year in cone yield in Chinese fir.The cone yield of most clones is greatly affected by on and off year.The cone yield of clones 24,25 and 28 is not less affected on and off-year.(2)There were significant differences in cone yield among different clones,and significant differences in cone morphological characteristics and seed traits.The variation coefficients of 11 seed and seed traits ranked from big to small:cone yield>volume>single fruit weight>1000-grain weight>germination rate>germination potential>fine degree>cone diameter>cone length>fruit shape index,being of 55.58%,51.42%,37.77%,20.99%,19.22%,18.89%,16.44%,15.43%,14.18%,8.04%.Generalized heritability ranged from big to small:1000-grain weight>single fruit weight>cone diameter>cone length>astringency rate>fruit volume>fruit shape index>germination rate>germination potential>cone yield,being of 0.988,0.977,0.976,0.976,0.966,0.963,0.949,0.934,0.873,0.610.It indicated that all characters were controlled by moderate or above.(3)There was no significant correlation between cone yield and cone morphological characteristics and seed traits,but there was a significant positive correlation between cone morphological characteristics and 1000-grain weight.There was a significant correlation among germination rate,germination potential and degree of excellence.There was a significant positive correlation between degree of excellence and germination potential.There was a significant negatively correlation with degree of excellence and percentage of astringent grain.(4)Clustering results of phenotypic traits showed,when the genetic distance was 13.75,30 clones were classified into 5 groups.Four principal components were extracted and the cumulative contribution rate was 85.491%by using principal component analysis.According to the score function,the highest synthetical score was 21,29 and 26 clones,and the lowest was 27 clones.The top 10 clones were selected,which could be used as garden materials for advanced generation seed orchards.(5)The quality and concentration of DNA extracted from Cunninghamia lanceolata meet the requirements of SSR-PCR follow-up experiments.According to the concentration,30 samples were diluted to a uniform concentration of 4.875ng/ul and stored in packages to prevent degradation caused by repeated freezing and thawing.The optimum annealing temperature and cycle number for each pair of primers were obtained by optimizing the annealing temperature and cycle number of primers on the established PCR system.The amplification effect was better when the cycle number was 33.(6)17 pairs of SSR marker primers amplified 56 polymorphic loci in 30 clones.Each pair of primers produced an average of 3.2 alleles,ranging from 2 to 6.The average effective allele was 2.2.Mean polymorphic information content(PIC)was 0.5431,ranging from 0.1285 to 0.9825.The average Nei’s diversity index was 0.4755,and the average Shannon diversity index was 0.8324,which indicated Chinese fir clones had high genetic diversity at molecular level and 17 SSR primers had high polymorphism.(7)The average genetic similarity of 30 clones was 0.6842 ranking from 0.5357～0.8929.It indicated that the genetic background between Chinese fir clones was complex.When the genetic similarity is 0.70 as the threshold,30 clones can be divided into 6 groups.The Chi-square test results showed that there was no significant correlation between phenotypic traits clustering and molecular marker clustering results,which indicated that there were abundant genetic variations in phenotypic traits and molecular level of Chinese fir. |
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