Single nucleotide polymorphism (SNP) characterization of drought-responsive genes to estimate genetic variation of Populus tremula var. davidiana and eight other Populus species.

To reveal the genetic mechanisms behind drought tolerance, we attempted to identify the drought-responsive genes in Populus tremula var. davidiana (Dode) C.K. Schneid. and eight other species of Populus. Nine drought-responsive genes were assayed by single nucleotide polymorphism (SNP) genotyping using TaqMan probe-based real-time PCR. A total of 346 SNPs were found from the 101 sequences of the nine genes. Among them, 57 primers were selected for SNP genotyping and haplotype determination. For the SNP genotyping, 56 assays were applicable to section Leuce Duby, 53 to section Aigeiros Duby, 50 to Populus maximowiczii Henry, and 52 to Populus simonii Carrière. The expectation maximization algorithm was implemented to determine haplotypes among species and sections. A total of 78 haploid types were estimated from nine drought-responsive gene loci, and the average number of haploid types per locus was 8.67. The analysis of genetic diversity revealed that P. tremula var. davidiana had substantial levels of genetic variation for the nine drought-responsive genes, which was higher than the eight other species. The means of observed number of alleles ( NA) and heterozygosity ( Ho) were 5.33 and 0.6609, respectively. Analysis of the genetic differentiation of P. tremula var. davidiana showed that 7.52% of genetic variation was among populations and the remaining was within a population. [ABSTRACT FROM AUTHOR]