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This research aimed to study the ectomycorrhiza formed by basidiospores attached to the outer surface of Shorea leprosula (Dipterocarpaceae) seed collected from a lowland tropical dipterocarp forest. Two groups of seeds were collected: control seeds collected from plastic net hanging 2 m above the ground and forest floor seeds collected on the forest floor. Before planting, 15 seeds from each group were observed for basidiospores attached to the seed. Ten of the 3-week-old S. leprosula seedlings of each group were individually grown in 1.5 kg of sterile zeolite for 8 months in a greenhouse. Pots were fertilized with MMN solution containing half the strength of phosphate. Fungal identity, ectomycorrhizal root tip colonization and anatomy, plant growth, and phosphate uptake were measured. The control seeds did not have basidiospores attached, whereas the forest floor seeds had 2 × 10 basidiospores of Tomentella. Bioassay test results indicate that the seedlings from the control seeds did not form ectomycorrhiza, whereas those seedlings from the forest floor seeds formed 3 morphotypes of ectomycorrhizae. Based on ITS1, 5.8S, and ITS2 rDNA region analyses, the 3 morphotypes belonged to Tomentella sp. HBT2, Tomentella sp. HBT4, and Scleroderma sp. HBS3. Root colonization percentage was above 70% for all three morphotypes. Root colonization in general increased plant growth and phosphate uptake. This is the first report of Tomentella basidiospores attached on the seed surface as a functional inoculum and of Tomentella ectomycorrhiza from dipterocarps lowland tropical forest. [ABSTRACT FROM AUTHOR]

We developed microsatellite markers from newly isolated expressed sequence tags of an endangered tropical tree species, Shorea leprosula (Dipterocarpaceae). Twenty-four loci exhibited clear, polymorphic amplification patterns among 52 individuals from a population in Indonesia, with two to 16 alleles per locus. No locus showed significant departure from Hardy-Weinberg equilibrium, and no significant genotypic disequilibrium was detected for any pair of loci after sequential Bonferroni correction. [ABSTRACT FROM AUTHOR]

Shorea (Dipterocarpaceae) is a large genus in which many closely related species often grow together in Southeast Asian lowland tropical rain forests. Many Shorea species share common pollinators, and earlier studies suggested occurrence of interspecific hybridization and introgression. Here, we show morphological and molecular evidence of hybridization between Shorea species. In the census of all the trees of Shorea curtisii, Shorea leprosula, and Shorea parvifolia (>30 cm dbh) within the 164-ha area of Bukit Timah Nature Reserve in Singapore, we found 21 morphologically recognizable hybrid individuals. All of the putative hybrids could be distinguished obviously from the parental species on the basis of vegetative characters. Population genetic analysis of DNA sequences of two nuclear ( GapC and PgiC) and chloroplast ( trnL- trnF) regions demonstrated that each of the three species had several species-specific mutations. The nuclear sequences of the putative hybrids were heterozygote at all the species-specific sites between two parental species. Hybrid between S. curtisii and S. leprosula was found most, while S. curtisii × S. parvifolia and S. leprosula × S. parvifolia hybrids were also found. Almost no shared polymorphism between populations of the parental species suggests rarity of introgression. The study indicated that natural hybridization between sympatric Shorea species should not be uncommon, but all of the hybrid individuals were F, and the post-F hybrids were considerably rare. [ABSTRACT FROM AUTHOR]

Phosphorus concentrations in many south-east Asian tropical rain forest soils are very low. To determine the growth responses of seedlings of a light-demanding ( Shorea leprosula) and a more shade-tolerant ( Hopea nervosa) dipterocarp species to increasing P, we carried out a nursery fertilisation experiment. Responses of symbiotic ectomycorrhizal (EcM) fungi to the treatments were also determined. Seedlings were grown under high light (13 mol m−2 d−1) or moderate light (4 mol m−2 d−1) in shade-chambers and were fertilised with a solution containing 0, 1, 10 or 100 mg L−1 P. The growth of Hopea and Shorea showed different responses to the light and P fertilisation treatments with Hopea having greater growth under moderate light conditions and Shorea having greater growth under high light conditions. Shorea responded to P fertilisation by increasing its foliar P concentrations and growth rates, whereas Hopea did not take up additional P and did not improve its growth rates. There was no effect of either light or P fertilisation on total EcM colonisation or EcM diversity, but around half of the EcM morphotypes observed were affected by one of these two abiotic perturbations, most notably for Riessiella sp. which increased with P fertilisation suggesting it may not be a mutualistic fungus. These results show how niche partitioning in both dipterocarp seedlings and EcM fungi can be divided along contrasting axes. [ABSTRACT FROM AUTHOR]

The genetic diversity within and among populations of Shorea leprosula and Shorea parvifolia from Indonesia was investigated using amplified fragment length polymorphisms (AFLPs). The results indicated that S. leprosula is genetically more variable than S. parvifolia. At the population level, a higher level of genetic diversity was revealed for S. leprosula with a percentage of polymorphic loci (PPLp) of 53.32% and an expected heterozygosity ( H ep) of 0.16 in comparison with S. parvifolia showing PPLp of 51.79% and H ep of 0.14. At the species level, S. leprosula showed PPLs of 92.86% and H es of 0.21, while S. parvifolia showed PPLs of 85.71% and H es of 0.21. Genetic differentiation ( G st) indicated that 25 and 31% of total genetic diversity in S. leprosula and S. parvifolia, respectively, were attributed to the differences among populations. An analysis of molecular variance (AMOVA) at two hierarchical levels exhibited that most genetic variation resided within populations with proportion of 70.2% for S. leprosula and 66.2% for S. parvifolia. The AMOVA at three hierarchical levels performed for S. leprosula and S. parvifolia together revealed that the genetic difference between the two species was remarkably higher with a proportion of 44.1% than the differences within and among populations (38.1 and 17.8%, respectively). The genetic differentiation between islands was significant for S. leprosula but not for S. parvifolia. The observed genetic diversity agreed with the life history traits of Shorea species. Highly differentiating individual AFLP markers were found for each species, which will serve as diagnostic markers for the identification of wood of different species, from different islands and regions. [ABSTRACT FROM AUTHOR]