匍匐茎草本植物蛇莓小尺度克隆结构

采用ISSR分子标记技术比较分析了3个斑块匍匐茎草本植物蛇莓的遗传多样性、克隆多样性和克隆结构,探讨蛇莓克隆结构的形成机制及与环境的相关性.结果表明蛇莓的遗传多样性较低,多态位点百分率P为37.93%, Shannon信息指数I为0.2402, Nei指数h为0.1677;蛇莓的克隆多样性与其它克隆植物较为接近,基因型比率G/N=0.2013,Simpson多样性指数D为0.6396,基因型分布的均匀度E为0.5862;蛇莓的遗传变异大部分存在于斑块间,基因流较小,仅为0.1019.3个斑块蛇莓的遗传多样性以临海斑块(LH)最高(P=10.34%, I =0.0513, h =0.0344),安吉斑块(AJ)次之(P=10.34%, I =0.0443, h =0.027),而天台斑块(TT)最低(P=5.17%, I =0.0325, h =0.0227).基株数目、基因型比率、Simpson多样性指数和基因型分布的均匀度均表明克隆多样性以LH斑块最大(G=12, G/N=0.3077, D=0.8677, E=0.8380),AJ斑块次之(G=9, G/N=0.1800, D=0.5870, E=0.4753),TT斑块最低(G=5, G/N=0.1163, D=0.4642, E=0.4453).3个斑块中均存在优势克隆,但优势克隆的大小在3个斑块中均不相同,以LH斑块最小,AJ斑块次之,TT斑块最大.空间自相关分析显示LH斑块在20 cm和40 cm时存在显著性正相关,其X轴截矩为49.959;AJ斑块仅在20 cm时存在显著性正相关,其X轴截矩为63.333;TT斑块在20 cm、30 cm、40 cm和70 cm时均存在显著性正相关,其X-轴截矩高达90.512.这表明3个不同斑块内蛇莓基因型的空间分布距离不同,TT斑块最大,AJ斑块最小;克隆所能到达的距离也不同,TT斑块最大,LH斑块最小.3个不同斑块蛇莓的遗传多样性、克隆多样性与克隆结构具有明显的差异.蛇莓的遗传多样性与克隆多样性与蛇莓较强的克隆繁殖能力和较低的种子萌发率有关.蛇莓的遗传结构、克隆结构及克隆的空间分布格局与不同斑块所处生境的生态因子及其它因素(如干扰、演替和突变)有关.

Fine-cale clonal structure of the stoloniferous herb Duchesnea indica

Genetic diversity, clonal diversity and clonal structure within the patches of the stoloniferous herb Duchesnea indica Focke were analyzed using inter-simple sequence repeat (ISSR) techniques. The relationship between clonal structure and habitat conditions was also studied to elucidate how clonal structure of D. indica was established. Genetic diversity of D. indica was relatively low: percentage of polymorphic loci (P) 37.93%, Shannon informative index (I) 0.2402, and Nei′s gene index (h) 0.1677. Clonal diversity of D. indica was similar to that of other clonal plant species. The proportion of distinguishable genotypes (G/N) was 0.2013, Simpson′s diversity index (D) 0.6396 and genotypic evenness (E) 0.5862. Both genetic diversity and clonal diversity of D. indica were the highest within the patch in Linhai City (LH), lowest within the patch in Tiantai City (TT), and intermediate within the patch in Anju City (AJ). Dominant clones were found in all three patches, but their size was the largest in the TT path, smallest in the LH patch and intermediate in the AJ patch. Spatial autocorrelation analysis showed that in the LH patch the autocorrelation coefficient was significantly positive at distances of 20 cm and 40 cm with an X-intercept of 49.959. In the AJ patch the correlation value was significantly positive at 20 cm with an x-intercept of 63.333 and in the TT patch it is positive and significant at 20 cm, 30 cm, 40 cm and 70 cm, respectively, with an X-intercept of 90.512. This indicates that the spatial autocorrelation scale of the genotype was highest within the TT patch, lowest in the AJ patch, and that the average length of genetic patches was the largest in the TT patch and smallest in the LH patch. The genetic diversity, clonal diversity and clonal structure of D. indica in three different patches were significantly different, which might be due to vegetative spreading and also the low seed germination rate. The ecological factors, together with others such as disturbance, succession and mutation, might have played important roles in the formation of the genetic structure, clonal structure and spatial distribution patterns.