| Machilus pauhoi Kanchira?Machilus?is an important tree species for quality timbers as well as for ornamental and the raw material for spices or medical use.It is naturally distributed in the subtropical regions in China,covering Guangdong,Guangxi,Fujian,Hunan,Jiangxi,Zhejiang and Anhui Provinces.The germplasm resources of M.pauhoi were collected from its natural area throughout China for the first time in this study.Geographic variation of seed traits,seedling growth traits and leaves volatile oil traits from different provences of M.pauhoi were studied.Besides,SRAP and SSR molecular marker techniques were used to analyse the genetic diversity of M.pauhoi as well.The main results were as following.1.There were significant differences in seed traits among provences.The aspect ratio became larger with the change of seed collection zone from south to north,and also the width thickness ratio became larger with the annual extreme maximum temperature of seed collection zone increased.Besides,the seed traits of length,width,thickness and hundred-seed weight increased with the average relative humidity of seed collection zone increased as well.The average variation of seed length,seed width,seed thickness and hundred-seed weight were 68.46%.It showed that the variation mainly existed among provenances.The 20 provenances were divided into three groups by cluster analysis.The first group included Chong-yi?CY?,Shun-chang?NP?and Jian-ou?JO?with the larger seed traits.The second group included Quan-nan?QN?,Ping-yang?PY?,Yong-chun?YC?and Long-yan?LY?with the smaller seed traits.And the third group included the rest of thirteen provences with the medium seed traits.2.There were significant differences in seedling height and diameter among different provences.The seedling height increased with the change of seed collection zone from west to east and the increase of elevation or the annual extreme maxium temperature.The heritability of seedling height and diameter were 0.9669 and 0.9652,respectively,which belonged to high heritability.The greater genetic gain could obtain in provenances selection.Such as Yong-chun?YC?,Xing-an?XA?,Yang-shan?YS?and Zhao-ping?ZP?were the fine provenances with greater additive effect value of seedling height and diameter in early seedling stage in Guangzhou province.3.The growth of seedling height and diameter showed the trend of slow-fast-slow.The seedling height and diameter growth had obvious asynchrony,and the rapid growth period of seedling diameter lagged behind the seedling height.There were two growth peaks of the seedling diameter in one year which means it was the growing tree species in Guangzhou province.4.The six kinds of aldehyde compounds were mainly found in the leaves volatile oil from different provences of M.pauhoi.Such as Octadecenal,Tetradecenal,Undecanal,Dodecyl aldehyde,Nonanal,Decanal.The Decanal and Dodecyl aldehyde were found in ten provences,while Nonanal was found in nine provences,Tetradecenal was found in eight provences,?-Caryophyllene was found in four provences and?-Cadinene was found in three pronvences.Other compounds were found only in one or two provences.The provenance Yang-shan?YS?contained fifty-seven chromatographic peaks which haved forty-seven compounds.The content of seven aliphatic compounds and forty terpenoids in the forty-seven compounds,were 81.85%and 18.15%,respectively.5.The results based on SSR marker were as following,the average number of alleles?Na?,effective alleles?Ne?,polymorphism information content?PIC?value,the observed heterozygosity?Ho?and expected heterozygosity?He?were 15.083,4.558,0.722,0.576 and 0.751,respectively.No significant linkage disequilibrium was detected among twelve SSR loci,suggesting independent segregation between different loci.The results based on SSR marker were as following,a total of 107 polymorphic bands with 145 bands were amplified by 12 SRAP primers.The average PIC,Shannon's information index?I?and Nei's gene diversity index?H?were 0.35,0.2515 and 0.1702,respectively.6.The means Na among twenty-four provences of M.pauhoi was 5.02�2.20.The Na values changed from 6.0 in Guangxi Province to 5.0 in Guangdong and Jiangxi Province,and to 3.0 or 4.0 in Fujian Province.There were many private alleles in the populations at the east side of the Xuefeng Mountain,such as Ling-chuan?GO?,Gong-cheng?GT?,Yang-shuo?GR?,Xing-an?XA?,Zhao-ping?ZP?and He-zhou?HE?.So the ranges could provide some refugia for plants during the Pleistocene glaciation.7.A further analysis with STRUCTURE indicating that the twenty-four populations were appropriately divided into three groups.Group I included Jian-ou?JO?,Shun-chang?NP?and Jiang-le?FO?in Fujian Province.Group II included Ling-chuan?GO?,Gong-cheng?GT?,Yang-shuo?GR?and Xing-an?XA?from Guangxi Province,Yong-chun?YC?and Long-yan?LY?from Fujian Province,and Chong-yi?CY?and Quan-nan?QN?from Jiangxi Province.Group III included the remaining thirteen provences.Group II was separated into two parts,with four populations?GO,GT,GR,and XA?being close to the Xuefeng Mountain and the other four populations?YC,LY,QN,and CY?at the east sides of the distribution.8.There was higher genetic diversity in M.pauhoi population.Population genetic differentiation in M.pauhoi(Gst=0.164)was medium and the genetic variation was mainly within provenances.Weak but significant effects of the isolation-by-distance existed in maintaining the population genetic variation in space.There was a certain gene flow?Nm=1.500?among the provences and a general northeastward dispersal in the distribution of M.pauhoi.All results implyed the mountain ranges was the major barrier to gene flow.9.The correlation between the similarity coeffcients matrix of SSR and SRAP was r=0.5029?P<0.050?,therefore SSR and SRAP were mismatched. |
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