Highly variable pollination patterns in Magnolia obovata revealed by microsatellite paternity analysis

The pattern and amount of effective pollen movement determine the regeneration process and the genetic structure of plant populations and are important for conservation measures. We inferred the pattern of effective pollen movement of the temperate canopy tree species Magnolia obovata from seedling paternity analysis using microsatellite markers. The 69-ha research site contained 83 reproductive trees of M. obovata. We analyzed 322 seedlings germinated from seeds collected from 14 flowers from three adult trees for their paternity. The proportion of seedlings originating from self-pollination was high ( 238 of 332, 70.8%). In contrast, no saplings at the site originated from self-pollination. Of 332 seedlings, 94 (29.2%) originated from outcrossing, with 35 (10.9%) sired by trees within the research site and 59 (18.3%) sired by unknown trees outside it. The composition of male parents, the rate of self-pollination, and long-distance pollen movement differed remarkably at the level of both flowers and trees, showing that the pollination process is highly variable. Relatively infrequent visits of effective pollinators and inbreeding depression seemed to determine the genetic characteristics of seedlings of M. obovata.