Genetic diversity of parental and offspring populations in a Pinus merkusii seedling seed orchard detected by microsatellite markers

Abstract

A seedling seed orchard (SSO) of Pinus merkusii was established by planting representatives of selected families from thirteen districts of Java Island, Indonesia over six years (1978-1983). The genetic diversity of the parental populations planted each year, and their offspring populations, was analyzed and compared using five microsatellite markers. The genetic differentiation among parent trees representing different districts was very small (FST=0.008), indicating (in accordance with previous proposals) that the genetic origins of the material in the SSO are limited. Consequently, values of FIS and L-D were significantly high in the parental populations. Differences in the values of genetic diversity parameters were statistically significant between the parental populations and their offspring populations. HE and Ne were higher in the offspring (mean=0.545 and 606.2, respectively) than in the parental populations (mean=0.489 and 486.5, respectively) in most of the blocks. The FST value of among population was smaller for the offspring populations that for the parental populations, 0.029 and 0.038, respectively. The results suggest that mating was random, or nearly random, and that gene flow was extensive in the orchard. New alleles were detected in offspring populations that were not found in the corresponding parental populations, indicating that gene flow from other blocks within the SSO, or from outside the SSO, has occurred.インドネシア，ジャワ島の13地域の人工林から選抜された家系を用いて1978年から1983年の間に造成された実生採種園において，母樹集団とそれから生産された次世代集団の遺伝的多様性を，5個のマイクロサテライトマーカーにより明らかにした。選抜地域間の遺伝的分化は，FST=0.008と小さかった。このことから，採種園の遺伝的由来は限られていることが分かった。その結果として，母樹集団ではFISが有意に大きくL-Dが高かった。遺伝的多様性のパラメーターの値は，母樹集団と次世代集団では有意に異なっており，ヘテロ接合度の期待値（HE）と集団の有効サイズ（Ne）は，次世代集団で平均0.545，606.2と，母樹集団のそれ（0.489と486.5）よりも高かった。FSTの値は次世代集団間で0.029，母樹集団間で0.038と次世代で集団間の分化程度が低かった。これらの結果から，採種園内で任意交配あるいはそれに近い交配が起こっており，遺伝子流動が盛んであることが推察された。次世代集団で母樹集団にはない新たな対立遺伝子が見られることから，他のブロックや採種園の外部からの園外花粉の流入が生じていることが示唆された