Abstract
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 (πT = 0.00622 and θW = 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.
Highlights
Larch (Larix olgensis) belongs to the family Pinaceae and is a rapidly growing and economically important conifer crop that produces wood for lumber, pulp, paper, and biofuel [1,2]
The genes for each step of the lignin biosynthesis pathway have been cloned, and the impact on lignin amount and composition has been explored in various species through the use of mutants or reverse genetics [6,10,11,12] little is known about the genetic variability within the genes coding for biosynthesis of lignin or other secondary cell wall components in larch
LoCAD, a highly targeted candidate gene belonging to key pathway of lignin biosynthesis, was investigated using a more comprehensive approach than those used in previous studies of conifers [42]
Summary
Larch (Larix olgensis) belongs to the family Pinaceae and is a rapidly growing and economically important conifer crop that produces wood for lumber, pulp, paper, and biofuel [1,2]. In the pulp and paper industry, lignin is an undesirable component in the conversion of wood to pulp and paper and should be eliminated by delignification during chemical pulping [8] Both the lignin content and composition influence the chemical pulping process, and trees with an altered lignin quantity or quality, or those with a desirable balance between lignin content, wood density and carbon storage are important in forest tree breeding programs. Little is known about the genetic variability within the genes that code for biosynthesis of lignin or other secondary cell wall components in larch. To develop markers associated with lignin content, we employed three methods: single SNPs, combinational-SNPs, and haplotype-based associations with wood properties and growth traits in a provenance trial These methods were used to investigate whether significant associations could be found in a Chinese larch landrace
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