Self-incompatibility of Samanea saman (raintree) as revealed by microsatellite analysis.

• Main Author: Poh, Kai Ling.
• Other Authors: Hong Yan
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Science::Biological sciences::Botany::Plant ecology
• Online Access: http://hdl.handle.net/10356/18961
• Institution: Nanyang Technological University

The raintree, Samanea saman, was first introduced into Singapore in 1876. Since then, it has beautified our landscape and offered welcome shade. However, there are no detailed records regarding the origin of these seed-derived trees. To better understand the genetic diversity of this important urban tree locally for future urban planning, we aim to study the pollination pattern and gene flow dynamics of S. saman using microsatellites. Microsatellites are invaluable tools for studying population genetics and mating systems. A total of 12 microsatellite loci (averaging 4.5 alleles each) were isolated, all of which displayed 100% polymorphism for S. saman. After genotyping with the 12 microsatellite loci, paternity analysis of 203 offspring was performed based on 11 mature trees in the study population, four of which were the seed parents. Even though the seed parents had viable pollen, paternity analysis revealed self-pollination in only 0.99% of the offspring. This led us to conclude that S. saman is predominantly self-incompatible. Observed heterozygosity among the offspring ranged from 0.384 to 0.897, indicating a satisfactory level of genetic diversity. Finally, the lack of strong correlation between cross-pollination pattern and physical distance between trees suggested that insects are the main pollinators of S. saman.