关键词: 格木, 濒危植物, 天然种群, 表型多样性, 表型性状, 种质资源

Abstract: [Objective] The phenotypic traits of pod and seed from an endangered plant Erythrophleum fordii were measured to investigate the phenotypic diversity and variation pattern of populations. And combing with geographical and climatic information, the factors affecting the phenotypic variation were discussed. This study provides a basis for genetic diversity conservation, restoration, and cultivation of E. fordii.[Method] The phenotypic characteristics of thirteen pods and seeds from 114 individuals of eight natural populations were measured. Nested analysis of variance, multi-comparison, correlation analysis, principal components analysis, and cluster analysis were used to study phenotypic diversity,evolution and adaptive potential, patterns of phenotypic variation, level of phenotypic differentiation, cluster of populations, and the correlation between phenotypic traits and climate factors, respectively.[Result] E. fordii showed a modest level of phenotypic diversity, the range of Shannon-Wiener index is from 1.911 1 (Shape index of seed) to 2.103 9 (Perimeter of pod)with an average of 2.027 8. The range of Shannon-Wiener index of eight populations is from 0.920 9(P6)to 1.885 6(P8) with an average of 1.474 7. The range of variation of variance among the 13 traits was from 7.544 6% (Length of seed)to 18.868 5%(Area of pod)with an average of 12.410 9%. The range of variation of variance among the eight populations was from 8.852 9%(P1) to 13.984 8%(P5) with an average of 12.410 9%. The range of times of maximum and minimum was from 1.395 2(Shape index of seed) to 2.805 6(Number of seeds in pod)with an average of 1.791 7. Analysis of nested variance showed that there was a significant differences (P<0.01) among and within populations, suggesting that abundant variation among and within populations. The within-population variation(40.387 1%) was much larger than the among-population variation(11.948 9%); and the average phenotypic population differentiation coefficient was 21.857 9% with a range from 7.476 5% (Shape index of seed)to 38.674 0% (Width of pod). Correlation analysis revealed that there were significant correlations among most phenotypic traits. The significantly negative correlation between the width of pod, length of seed and perimeter of seed was detected, whereas, there were significantly positive correlations between width of pod and latitude. The pod and seed were mostly found small in the areas with high temperature and rainfall in general, and the size of pod and seed became bigger and bigger along with the increase of the latitude and the decrease of the temperature. Principal component analysis showed that the four principal components added up to 87.382% of the variation. The eight natural populations were divided into three groups by UPGMA cluster analysis based on Euclidean distance calculated from phenotypic traits. The first group was comprised of populations with small pods and small seeds, which are located in the south of the natural distribution. The second group has characteristics of big pods and big seeds, which are located in the north of the natural distribution, and only one population is located in the south of the distribution. Populations with small pods, big and thin seeds are located in the middle of the distribution, belonging to the third group.[Conclusion] E. fordii has the modest level of phenotypic diversity, there were abundant variations among and within populations. The degree of phenotypic variation was slight and stable, and there was low level of population differentiation in E. fordii. Within-population variation was the main source of variation. For germplasm collection and preservation, the number of populations can be reduced while the number of individual trees within populations can be increased, especially the individuals with unique phenotypic characteristics. Rongxian and Longxu of Guangxi are the most important regions for genetic conservation and germplasm collection. Temperature was the most important factor affecting the phenotypic traits and distribution of E. fordii. Pod and seed sizes are the basis for populations clustering.

Key words: Erythrophleum fordii, endangered plant species, natural population, phenotypic diversity, phenotypic traits, germplasm resources