Allelic Variation in Cinnamyl Alcohol Dehydrogenase (LoCAD) Associated with Wood Properties of Larix olgensis

Cinnamyl alcohol dehydrogenase (CAD) catalyzes the key step in the lignin monomer biosynthesis pathway, but little is known about CADs in larch (Larix olgensis). Larch is one of the most important conifer plantation species and is used worldwide for reforestation and paper making. However, the presence of lignin is a significant barrier in the conversion of plant biomass to bioethanol. In the current study, 240 individuals from the Northeast Forest University provenance progeny trial population were evaluated, and 47 single-nucleotide polymorphisms (SNPs) were identified in the CAD gene. We used a candidate gene-based association mapping approach to identify CAD gene allelic variants that were associated with growth and wood property traits in L. olgensis. We found that LoCAD harbors high single nucleotide polymorphism (SNP) diversity (pi(T) = 0.00622 and theta(W) = 0.00646). The results of an association analysis indicated that nine SNPs and six haplotypes were significantly associated with wood property and growth traits, explaining between 1.35% and 18.4% of the phenotypic variance. There were strong associations between SNP (g.590G > T) and SNP (g.1184A > T) in LoCAD. These SNPs might represent two quantitative trait nucleotides that are important for the analysis of lignin content.