Microsatellite analysis of the mating system of Bruguiera gymnorrhiza and Kandelia obovata

¹ Universitas Sumatera Utara, Department of Forestry, Faculty of Forestry, Jl. Tri Dharma Ujung No. 1 Medan, North Sumatera 20155, Indonesia
² Universitas Sumatera Utara, Mangrove and Bio-Resources Group, Center of Excellence for Natural Resources Based Technology, Medan North Sumatera 20155, Indonesia
³ University of the Ryukyus, International Society for Mangrove Ecosystems, Faculty of Agriculture, 1 Senbaru, Nishihara, Okinawa 903-0213, Japan
⁴ University of the Ryukyus, Molecular Biotechnology Group, Tropical Biosphere Research Center, 1 Senbaru, Nishihara, Okinawa 903-0213, Japan

^* Corresponding author: m.basyuni@usu.ac.id

Abstract

Microsatellite loci were used for estimating mating system for three populations of B. gymnorrhiza and K. obovata (Rhizophoracea) in Okinawa, Japan. Mother trees and thirty offspring of individual samples representing the population of both species were genotyped at five microsatellites. The mating system was examined using two approaches: a mixed mating model of multilocus testing, implemented by MLTR program and outcrossing rate from the level of inbreeding. Mating system analysis showed multilocus outcrossing rates (tm) for both species was 0.850-1.000 and 0.780-0.938 respectively. By contrast, according to inbreeding level, tm was lower than MLRT: 0.495-1.028 and 0.480-0.612 of both species respectively. However, biparental inbreeding (tm- ts) was diverse from zero both species for all three populations, showing that cross-fertilization events may ensue between the relatives both species. This data as well means the genetic relatedness (r) for B. gymnorrhiza and K. obovata were 0.108±0.025 and 0.032±0.09 respectively. Average relatedness was below 0.25, the value for a half-sib relationship. These results suggest that postulation of a half-sib relationship among progeny of open-pollinated families is opposed for both mangrove tree species.