Microsatellite Paternity Analysis Used for Evaluation of Outcrossing Rate Among Five Hevea Rubber Clones in a Systematic Seed Orchard

Afirstgenerationofsyntheticrubber�(Hevea brasiliensis) clones derived from a polycross among multiple parents was produced to establish a seed orchard that will be useful to systematically enhance cross-pollination among several clones and breed superior rubber genotypes. The objective of thisstudywastoevaluatethefloweringpatternsandoutcrossingrateamongfiveHevea rubber clones within this seed orchard using microsatellite markers. Five rubber clones (AVROS 2037, BPM 1, IAN 873, PB 260 and RRII 118) were systematically grown in a random design with spacing of 7 × 7 m in a seed orchard at the Phetchabun Highland Agricultural Development and Research Center, KhaoKho, Phetchabun (16°35" N and 100°57" E), Thailand. Five pairs of polymorphic microsatellite primers were usedtoanalyze�288�seedlingsderivedfromtheseedorchard.�Thefivemicrosatellitelocichosenforthis� study were highly polymorphic, with a mean of 5.8 alleles per locus and a combined exclusion probability of�0.988553,�bothofwhichweresufficientlyhightocorrectlyassignparentage.�Individualfemale� parents varied in their estimated outcrossing rate from 58.62 to 98.36%, while the overall outcrossing rateintheseedorchardwas�79%�andselfingratewas�21%.�Pollencontaminationwasnotobservedin� this seed orchard. The high outcrossing level and the lack of pollen contamination may be useful for the establishment of a seed production facility and for the management of hybrid production.