National Engineering Laboratory for Tree Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China.
PLoS One. 2013 Apr 16;8(4):e60880. doi: 10.1371/journal.pone.0060880. Print 2013.
In woody crop plants, the oligosaccharide components of the cell wall are essential for important traits such as bioenergy content, growth, and structural wood properties. UDP-glucuronate decarboxylase (UXS) is a key enzyme in the synthesis of UDP-xylose for the formation of xylans during cell wall biosynthesis. Here, we isolated a multigene family of seven members (PtUXS1-7) encoding UXS from Populus tomentosa, the first investigation of UXSs in a tree species. Analysis of gene structure and phylogeny showed that the PtUXS family could be divided into three groups (PtUXS1/4, PtUXS2/5, and PtUXS3/6/7), consistent with the tissue-specific expression patterns of each PtUXS. We further evaluated the functional consequences of nucleotide polymorphisms in PtUXS1. In total, 243 single-nucleotide polymorphisms (SNPs) were identified, with a high frequency of SNPs (1/18 bp) and nucleotide diversity (πT = 0.01033, θw = 0.01280). Linkage disequilibrium (LD) analysis showed that LD did not extend over the entire gene (r (2)<0.1, P<0.001, within 700 bp). SNP- and haplotype-based association analysis showed that nine SNPs (Q <0.10) and 12 haplotypes (P<0.05) were significantly associated with growth and wood property traits in the association population (426 individuals), with 2.70% to 12.37% of the phenotypic variation explained. Four significant single-marker associations (Q <0.10) were validated in a linkage mapping population of 1200 individuals. Also, RNA transcript accumulation varies among genotypic classes of SNP10 was further confirmed in the association population. This is the first comprehensive study of the UXS gene family in woody plants, and lays the foundation for genetic improvements of wood properties and growth in trees using genetic engineering or marker-assisted breeding.
在木本作物中，细胞壁中的低聚糖成分对于生物能源含量、生长和结构性木材特性等重要性状至关重要。UDP-葡萄糖醛酸脱羧酶（UXS）是细胞壁生物合成过程中形成木聚糖的 UDP-木糖合成的关键酶。在这里，我们从毛白杨中分离出一个多基因家族的七个成员（PtUXS1-7），这些成员编码 UXS，这是对树种中 UXS 进行的首次研究。基因结构和系统发育分析表明，PtUXS 家族可以分为三组（PtUXS1/4、PtUXS2/5 和 PtUXS3/6/7），与每个 PtUXS 的组织特异性表达模式一致。我们进一步评估了 PtUXS1 中核苷酸多态性的功能后果。总共鉴定出 243 个单核苷酸多态性（SNP），SNP 频率高（1/18bp），核苷酸多样性（πT=0.01033，θw=0.01280）。连锁不平衡（LD）分析表明，LD 没有扩展到整个基因（r（2）<0.1，P<0.001，在 700bp 内）。SNP 和单倍型关联分析表明，在关联群体（426 个个体）中，有 9 个 SNP（Q<0.10）和 12 个单倍型（P<0.05）与生长和木材特性显著相关，解释了 2.70%至 12.37%的表型变异。在 1200 个个体的连锁图谱群体中验证了 4 个显著的单标记关联（Q<0.10）。此外，在关联群体中还进一步证实了 SNP10 的基因型类别的 RNA 转录积累存在差异。这是木本植物中 UXS 基因家族的首次全面研究，为利用遗传工程或标记辅助选择进行树木的木材特性和生长的遗传改良奠定了基础。
