基于种实表型性状和SSR标记的杉木2代种子园遗传多样性分析

Genetic diversity analysis of 2-generation seed orchard of Cunninghamia lanceolata based on phenotypic cone and seed traits and SSR marker

【目的】从表型和分子2个角度评估江西信丰县国家杉木良种基地杉木2代种子园的遗传多样性,明确种子园的遗传背景,为后期种子园的改良(去劣疏伐)、重建(亲本选择与配置)等提供依据,同时为开展杂交育种提供遗传信息。【方法】以江西信丰杉木2代种子园内51个建园无性系为研究对象,通过分析8个种实表型性状掌握种子园不同无性系间种实性状的差异,同时利用SSR标记从DNA水平进行遗传多样性评估。【结果】供试51个无性系在种实表型性状和DNA水平上均存在明显的变异和较丰富的遗传多样性。8个表型性状变异系数为10.53%~37.04%,其中球果和种子的平均变异系数分别为18.99%和14.01%,种子的变异系数较小,表明种子的稳定性要比球果的高;种实性状的Shannon-Weaver多样性信息指数平均为2.060,表明种实性状的多样性较丰富。在DNA水平,14个SSR标记在51个无性系中共扩增出68个等位位点,平均Shannon’s信息指数、平均Nei’s遗传多样性指数、平均观测杂合度和平均期望杂合度分别为0.925、0.506、0.486和0.511,表明信丰杉木2代种子园遗传多样性较丰富。基于种实表型性状和SSR标记均可将51个无性系分为两大类群,但两者的具体聚类结果存在较大差异,Mantel检验显示种实性状与SSR标记之间不存在相关性(r=0.064,P=0.870>0.05)。【结论】信丰杉木2代种子园遗传多样性较丰富,具有再选择空间和改良潜力。

【Objective】To evaluate the level of genetic diversity and genetic background of 2-generation seed orchard of Cunninghamia lanceolata based on phenotypic cone and seed traits and SSR marker,and provide a basis for the improvement,reestablishment of seed orchard,meanwhile provide the genetic information for crossbreeding.【Method】The 2-generation seed orchard of C.lanceolata at Xinfeng forest farm were used to analyze their difference in the cone and seed by phenotypic traits,and to analyze their genetic diversity by SSR markers.【Result】There were high levels of genetic diversity existed in 2-generation seed orchard.The coefficients of variation of the 8 phenotypic traits ranged from 10.53%to 37.04%,the variation coefficients of cone and seed phenotypic traits were 18.99%and 14.01%,respectively.The stability of cone was lower than that of seed.The mean Shannon-Wiener index of phenotypic cone and seed traits was 2.060,indicating that the diversity of cone and seed traits was abundant.A total of 68 alleles were detected in 51 clones using 14 SSR markers,the means of Shannon’s information index,Nei’s genetic diversity index,observed heterozygosity,and expected heterozygosity were 0.925,0.506,0.486,and 0.511,respectively.It indicated that the genetic diversity of 2-generation seed orchard of C.lanceolata at Xinfeng forest farm was high.Both phenotypic trait analysis and the SSR marker analysis classified the 51 clones into two groups,however,there was no correlation between them by mantel test(r=-0.064,P=0.870>0.05),which mean the results obtained by the two methods were different.【Conclusion】There were abundant genetic diversity with re-selected spaces and potential of genetic improvement in 2-generation seed orchard in Xinfeng.