The Arabidopsis irregular xylem8 mutant is deficient in glucuronoxylan and homogalacturonan, which are essential for secondary cell wall integrity
The Arabidopsis irregular xylem8 mutant is deficient in glucuronoxylan and homogalacturonan, which are essential for secondary cell wall integrity
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DOI：
10.1105/tpc.106.047720
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发表时间：
2007-01-01
期刊：
影响因子：
11.6
通讯作者：
Somerville, Chris
中科院分区：
文献类型：
--
作者：
Persson, Staffan;Caffall, Kerry Hosmer;Somerville, Chris
高等植物的次生细胞壁主要由纤维素、木质素和木聚糖组成，是许多物种生物量的主要组成部分。拟南芥不规则xylem8（irx8）突变体是矮化的，并且具有次生细胞壁厚度的显著减少。IRX8属于糖基转移酶家族8的一个亚组，称为GAUT1相关基因家族，其成员包括GAUT1（一种同型半乳糖醛酸聚糖半乳糖醛酸转移酶）和GAUT12（IRX8）。在这里，我们使用比较细胞壁分析表明，irx8突变体含有显着降低水平的木聚糖和同型半乳糖醛酸。免疫组织化学分析证实，木聚糖的水平显着降低的突变体。细胞壁聚合物的结构指纹进一步揭示了irx8缺乏葡糖醛酸木聚糖。为了探索IRX8的生物学功能，我们将irx8与irx1（影响纤维素合成酶8）杂交。纯合子irx1 irx8表现出严重的矮化表型，表明IRX8是必不可少的纤维素缺乏过程中的细胞壁完整性。两者合计，所呈现的数据表明，IRX8影响高等植物中的葡糖醛酸木聚糖和同型半乳糖醛酸的水平，并且IRX8提供木聚糖聚合物和次生细胞壁基质之间的重要联系，并直接影响次生细胞壁的完整性。
The secondary cell wall in higher plants consists mainly of cellulose, lignin, and xylan and is the major component of biomass in many species. The Arabidopsis thaliana irregular xylem8 (irx8) mutant is dwarfed and has a significant reduction in secondary cell wall thickness. IRX8 belongs to a subgroup of glycosyltransferase family 8 called the GAUT1-related gene family, whose members include GAUT1, a homogalacturonan galacturonosyltransferase, and GAUT12 ( IRX8). Here, we use comparative cell wall analyses to show that the irx8 mutant contains significantly reduced levels of xylan and homogalacturonan. Immunohistochemical analyses confirmed that the level of xylan was significantly reduced in the mutant. Structural fingerprinting of the cell wall polymers further revealed that irx8 is deficient in glucuronoxylan. To explore the biological function of IRX8, we crossed irx8 with irx1 ( affecting cellulose synthase 8). The homozygous irx1 irx8 exhibited severely dwarfed phenotypes, suggesting that IRX8 is essential for cell wall integrity during cellulose deficiency. Taken together, the data presented show that IRX8 affects the level of glucuronoxylan and homogalacturonan in higher plants and that IRX8 provides an important link between the xylan polymer and the secondary cell wall matrix and directly affects secondary cell wall integrity.