Genetic Structure in a Core Subset of Pinus Massoniana Lamb. Germplasm

The genetic structure of a plant species gene pool has become increasingly important in plant association mapping research. Many advanced molecular techniques have been applied to assess the genetic diversity in a plant gene pool. Masson pine (Pinus massoniana Lamb.) is one of the most important native coniferous trees for timber plantation and resin production in southern China. A core subset of 121 Masson pine individuals, representing 33 populations from two gene pools, was planted at Guiyang National Orchard in Hunan province and were screened using 11 ISSR markers. The ISSR primers detected 258 polymorphic bands with frequencies ranging from 0.053 to 0.936 (mean 0.457). Population-specific ISSR variation (P) ranged from 68.46% to 94.23% (mean 81.04%) among 10 geographical distribution populations. The genetic differentiation among populations revealed different patterns of ISSR variation, of which 10.77% ISSR variation among 33 populations, 6.88% variation among 10 geographical distributions, 5.45% variation among different seed sources, and 2.46% ISSR variation in agronomic traits such as DBH. The above germplasm classification was further supported from principal component and neighbor-joining analyses. The most genetically distinct germplasm was identified with the individuals’ dissimilarity that ranged from 0.322 to 0.426. A mini core subset of 50 genotypes from 33 populations representing 10 geographical distributions was thus developed for further structural inferences. The inferred optimal clusters provided the best possible structural description of the current Masson pine gene pool. This characterization effort could provide a set of baseline information for the future masson pine research associated with gene mapping and marker-assisted breeding.