红树植物木榄(Bruguiera gymnorrhiza)种群的交配系统

MATING SYSTEM OF BRUGUIERA GYMNORRHIZA POPULATIONS OF MANGROVE, CHINA

利用等位酶多态位点作遗传标记 ,采用水平切片淀粉凝胶电泳技术检测了我国福建浮宫 (2 4°2 4′)、广东深圳福田 (2 2°32′)、广西山口合浦 (2 1°2 8′)和海南东寨港 (19°5 1′) 4个红树植物分布区内木榄种群的基因型 ,进而利用多位点异交率估测程序 (ML T)估测其交配系统。所用多态酶位点在浮宫、广西、海南均为 Mdh- 1、Mdh- 2、Me- 1,在深圳为 Mdh- 1、Mdh- 2、Aat- 1、Aat- 2。结果表明 :各种群多态位点异交率之间有很大差别 ,浮宫种群最大 ,为 0 .845 ;海南种群最小 ,为 0 .2 6 7。多位点异交率与单位点异交率平均值的差值显示出除广西种群为随机交配外 ,其余 3个种群都存在轻度的双亲近交。因此 ,木榄属于混合交配类型 ,以杂交为主。这主要受植物种群密度、结构 。

We investigated genotypic variation in 4 Bruguiera gymnorrhiza (mangrove) populations using horizontal sliceable gel electrophoresis for polymorphic loci of allozymes as a genetic marker. Mating system was also investigated with MLT. The four populations studied were located between 24°24′N and 19°51′N on the Chinese coast at (from N to S) Fugong (Fujian), Futian (Guangdong), Shankou(Guangxi) and Dongzhai Horbor (Hainan). The polymorphic loci selected for analysis differed among the four populations: Mdh-1, Mdh-2,Me-1 in Fugong, Guangxi and Hainan and Mdh-1,Mdh-2,Aat-1,Aat-2 in Shenzhen. A strong difference in outcrossing rates of polymorphic loci was found: Fugong, at 0 845, had the highest rate while Hainan, 0 267, was the smallest. The difference between outcrossing rates of polymorphic loci and the mean outcrossing rates of monomorphic loci in these four areas also varied, showing slight biparental inbreeding in the mating system of the Fugong, Guangxi and Hainan populations but random crossing in the Guangxi population. We conclude the Bruguiera gymnorrhiza is a mixed-mating species and the mating system is mainly outcrossing.This is influenced by factors such as plant population density and structure and the adaptability of pollinator as well the presence or absence of self-incompatibility mechanisms.