摘要
以采自广西区 11个西南桦 (Betulaalnoides)天然居群的种子培育出的幼苗为材料 ,取其嫩叶开展 2 1种酶系统的水平切片淀粉凝胶电泳实验 ,运用作者改进的Tris_马来酸提取缓冲液 (含 30 %PVP 40 0 0 0和 1% 2_巯基乙醇 ) ,筛选出AMP(氨基肽酶Aminopeptidase)、FBA(果糖二磷酸酶Fructose_bisphosphatealdolase)、GDH(谷氨酸脱氢酶Glutamatedehydrogenase)、G6PD(6_磷酸葡萄糖脱氢酶Glucose_6_phosphatedehydrogenase)、IDH(异柠檬酸脱氢酶Isoci tratedehydrogenase)、MDH(苹果酸脱氢酶Malatedehydrogenase)、PGD(6_磷酸葡萄糖酸脱氢酶Phosphogluconatedehydro genase)、PGI(磷酸葡萄糖异构酶Phosphoglucoisomerase)、PGM(磷酸葡萄糖变位酶Phosphoglucomutase)和SKD(莽草酸脱氢酶Shikimatedehydrogenase)等 10种酶 ,获得了清晰且可重复的酶谱。通过谱带遗传分析确定了 15个位点 ,其中有 6个单态位点 ,9个多态位点 (0 .95标准 ) ,具 40个等位基因。在居群水平上 ,西南桦的多态位点百分数 (P)为5 5 .2 % ,平均每个位点的等位基因数 (A)为 2 .0 0 ,平均预期杂合度 (He)为 0 .2 0 4。均超过Hamrick (1992 )等提出的远交风媒木本植物的平均值 (5 3 .0 % ,1 84%和 0 15 4) ,表明西南桦的遗传变异水平高。在 11个?
Betula alnoides is a valuable tree species in tropical and warm sub_tropical areas in South_east Asia and China. Its natural populations have become increasingly fragmented due to over_harvesting for local economic development in Guangxi, China during the last decade. Thus conservation of its genetic resources is of urgent need for future genetic improvement programs and sustainable management. Here, the allozyme diversity of Betula alnoides was analyzed by starch gel electrophoresis with improved Tris_maleate extraction buffer. Young leaves were collected from seedlings grown by seeds from 11 natural populations in Guangxi, China. Of the 21 enzymes tested, 10 (AMP, FBA, GDH, G6PD, IDH, MDH, PGD, PGI, PGM and SKD) could be consistently resolved and scored. Among 15 interpretable loci there were 9 polymorphic loci (0.95 criterion); the remaining 6 loci were monomorphic. High genetic variability was quantified by three indices: percentage of polymorphic loci ( P ), mean number of alleles per locus ( A ) and mean expected heterozygosity ( He ). The observed values of these indices were 55.2%, 2.00 and 0.204 respectively, all of which were higher than the averages of outcrossing wind_pollinated woody species (53.0%, 1.84 and 0.154, summarized by Hamrick et al., 1989). Ho was always higher than He in the 11 populations, indicating an excess of heterozygotes, which perhaps resulted from a higher probability of survival for heterozygous individuals. No significant correlation was detected between the genetic diversity and geographic variables of these populations. It is worth noting that populations 2 (Dizhou, Jingxi County), 5 (Haicheng, Pingguo County) and 9 (Zhemiao, Tianlin County) should be selected and managed as in_situ conservation localities, because they contain a majority of alleles and high levels of genetic diversity. The method and findings in this study could be applied in further studies on the genetic structure, diversity and genetic improvement of this species and other spec
出处
《植物生态学报》
CAS
CSCD
北大核心
2003年第1期66-72,共7页
Chinese Journal of Plant Ecology
基金
国家科技攻关项目 ( 96-0 11-0 2-0 2-0 3
2 0 0 2BA5 15B0 2 0 4)
关键词
广西区
西南桦
天然居群
遗传多样性
Betula alnoides, Natural population, Allozyme, Genetic diversity
