Mating System Analysis of <i>Acacia auriculiformis</i> in First and Second Generation Orchard Populations

Abstract

Acacia auriculiformis A.Cunn.ex Benth is one of the fast growing exotic timber species. Thorough understanding of mating systems is influencing towards an efficient tree breeding design. Thus plant mating systems play an important role in shaping the genetic composition of progeny generations. Institute of Forest Genetics & Tree Breeding (IFGTB), Coimbatore has established Seedling Seed Orchards of Acacia auriculiformis in Southern States (Tamil Nadu and Kerala) of India. Two successive generations of this species were studied for its mating system based on microsatellite markers. Five microsatellite loci were studied among the three hundred half-sib progenies of both first and second orchard populations. Out-crossing rate was estimated The range of the maternal, paternal genotypes among the individuals in the family was also studied in the orchards. The present study indicated high out-crossing rate in first and second generation orchards population and it reflects that this species is highly out-crossed. The gene frequency estimates of the first and second generation progenies were studied that there was no significant variation in the pollen and ovule gene frequency estimate in both generations. The range of the maternal genotypes was 1 to 2 among the individuals in the family. The high out-crossing rate (tm=0.98; SE= 0.05; tm=1.0; SE=0.02) in the orchards indicated that the species is predominantly out-crossed.