Single nucleotide polymorphisms in two GID1 orthologs associate with growth and wood property traits in Populus tomentosa

Abstract

Gibberellic acids (GAs) have multiple functions in various stages of plant growth and wood development, and GA receptor GIBBERELLIN INSENSITIVE DWARF 1 (GID1) is a key player in GA signaling. Here, we used association studies to examine the allelic variation within PtoGID1a and PtoGID1b associated with growth and wood properties in a natural population of Populus tomentosa. We isolated two full-length PtoGID1a and PtoGID1b cDNA by reverse transcription PCR, and both of these two genes had an open reading frame with the same length (1035 bp) and encoded a protein of 344 amino acids. Analysis of tissue-specific expression profiles indicated that these two genes had similar transcription patterns, being expressed predominantly in leaves. Nucleotide diversity and linkage disequilibrium (LD) analysis showed that PtoGID1a and PtoGID1b harbor high single nucleotide polymorphism (SNP) diversity (π Τ = 0.08237 and 0.00921, respectively) and low LD (r 2 > 0.1, within 350 and 1000 bp, respectively). SNP- and haplotype-based association tests identified that six single SNPs (Q < 0.05) and six haplotypes (P < 0.05, Q < 0.10) were significantly associated with growth and wood properties, explaining 0.99–10.28 and 3.10–5.39 % of the phenotypic variance, respectively. Therefore, isolation of PtoGID1a and PtoGID1b and dissection of their allelic polymorphisms open an avenue to understand the regulation of PtoGID1 in the growth and wood formation in trees.