Analysis of the Arabidopsis IRX9/IRX9-L and IRX14/IRX14-L Pairs of Glycosyltransferase Genes Reveals Critical Contributions to Biosynthesis of the Hemicellulose Glucuronoxylan
Analysis of the Arabidopsis IRX9/IRX9-L and IRX14/IRX14-L Pairs of Glycosyltransferase Genes Reveals Critical Contributions to Biosynthesis of the Hemicellulose Glucuronoxylan
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DOI：
10.1104/pp.110.154971
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发表时间：
2010-06-01
期刊：
影响因子：
7.4
通讯作者：
Marchant, Alan
中科院分区：
文献类型：
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作者：
Wu, Ai-Min;Hornblad, Emma;Marchant, Alan
半纤维素葡糖醛酸木聚糖（GX）是植物次生细胞壁的主要成分。然而，我们对GX合成的理解仍然有限。在这里，我们确定并分析了两个新的基因，从拟南芥（拟南芥），不规则XYLEM 9-LIKE（IRX 9-L）和IRX 14-LIKE（IRX 14-L），编码糖基转移酶家族43成员提出木聚糖骨架延伸过程中发挥作用。我们将IRX 9-L和IRX 14-L与先前描述的六个糖基转移酶基因（IRX 9，IRX 10，IRX 10-L，IRX 14，脆性纤维8 [FRA 8]和FRA 8同源蛋白[F8 H]）置于遗传框架中，并研究它们在GX合成中的功能。双突变体分析将IRX 9-L和IRX 14-L分别鉴定为IRX 9和IRX 14的功能同源物。irx 9 irx 10 irx 14 fra 8和irx 9-L irx 10-L irx 14-L f8 h四重突变体的表征允许定义一组包含在营养发育期间GX合成中起主要作用的IRX 9、IRX 10、IRX 14和FRA 8的基因。IRX 9-L、IRX 10-L、IRX 14-L和F8 H基因能够部分取代其各自的同源物，并且通常执行次要功能。irx 14 irx 14-L双突变体实际上缺乏木聚糖，而irx 9 irx 9-L和fra 8 f8 h双突变体形成的GX量降低，显示出主链聚合度大大降低。我们的研究结果揭示了两组不同的四个基因，每一个差异有助于GX生物合成。
The hemicellulose glucuronoxylan (GX) is a major component of plant secondary cell walls. However, our understanding of GX synthesis remains limited. Here, we identify and analyze two new genes from Arabidopsis (Arabidopsis thaliana), IRREGULAR XYLEM9-LIKE (IRX9-L) and IRX14-LIKE (IRX14-L) that encode glycosyltransferase family 43 members proposed to function during xylan backbone elongation. We place IRX9-L and IRX14-L in a genetic framework with six previously described glycosyltransferase genes (IRX9, IRX10, IRX10-L, IRX14, FRAGILE FIBER8 [FRA8], and FRA8 HOMOLOG [F8H]) and investigate their function in GX synthesis. Double-mutant analysis identifies IRX9-L and IRX14-L as functional homologs of IRX9 and IRX14, respectively. Characterization of irx9 irx10 irx14 fra8 and irx9-L irx10-L irx14-L f8h quadruple mutants allows definition of a set of genes comprising IRX9, IRX10, IRX14, and FRA8 that perform the main role in GX synthesis during vegetative development. The IRX9-L, IRX10-L, IRX14-L, and F8H genes are able to partially substitute for their respective homologs and normally perform a minor function. The irx14 irx14-L double mutant virtually lacks xylan, whereas irx9 irx9-L and fra8 f8h double mutants form lowered amounts of GX displaying a greatly reduced degree of backbone polymerization. Our findings reveal two distinct sets of four genes each differentially contributing to GX biosynthesis.