UDP-glucose 4-epimerase isoforms UGE2 and UGE4 cooperate in providing UDP-galactose for cell wall biosynthesis and growth of Arabidopsis thaliana
UDP-glucose 4-epimerase isoforms UGE2 and UGE4 cooperate in providing UDP-galactose for cell wall biosynthesis and growth of Arabidopsis thaliana
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DOI：
10.1105/tpc.106.049619
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发表时间：
2007-05-01
期刊：
影响因子：
11.6
通讯作者：
Seifert, Georg J.
中科院分区：
文献类型：
--
作者：
Rosti, Johannes;Barton, Christopher J.;Seifert, Georg J.
拟南芥中编码UDP-葡萄糖4-差向异构酶（UGE）的5个基因代表了两个古老的植物UGE分支，可能参与细胞壁碳水化合物的生物合成调控。我们在全基因组反向遗传研究中验证了这一假设。尽管每个基因对总UGE活性的贡献很大，但没有一个是土壤正常生长所必需的。UGE 2、UGE 4表现出显著的一般生长缺陷，而其它突变体组合是部分异常的。UGE 2和UGE 3共同影响花粉发育。UGE 2和UGE 4协同影响细胞壁半乳糖含量，这与芽生长。UGE 2通过影响半乳聚糖含量而影响根系生长和细胞壁半乳糖含量，而UGE 1和UGE 5的作用较弱。相比之下，只有UGE 4影响根中的木葡聚糖半乳糖基化。次生下胚轴加厚和木质部薄壁组织中阿拉伯半乳聚糖蛋白碳水化合物结构依赖于UGE 2和UGE 4的组合。与细胞壁半乳糖含量相反，对外部半乳糖的耐受性严格限制总UGE活性。我们建议逐步招募个别UGE亚型到特定的角色。UGE 2和UGE 4影响整个植物的生长和细胞壁碳水化合物的生物合成，UGE 3专门用于花粉发育，UGE 1和UGE 5可能在胁迫情况下起作用。
Five Arabidopsis thaliana genes that encode UDP-glucose 4-epimerase (UGE) and represent two ancient plant UGE clades might be involved in the regulation of cell wall carbohydrate biosynthesis. We tested this hypothesis in a genome-wide reverse genetic study. Despite significant contributions of each gene to total UGE activity, none was essential for normal growth on soil. uge2 uge4 displayed dramatic general growth defects, while other mutant combinations were partially aberrant. UGE2 together with UGE3 influenced pollen development. UGE2 and UGE4 synergistically influenced cell wall galactose content, which was correlated with shoot growth. UGE2 strongly and UGE1 and UGE5 lightly supported UGE4 in influencing root growth and cell wall galactose content by affecting galactan content. By contrast, only UGE4 influenced xyloglucan galactosylation in roots. Secondary hypocotyl thickening and arabinogalactan protein carbohydrate structure in xylem parenchyma depended on the combination of UGE2 and UGE4. As opposed to cell wall galactose content, tolerance to external galactose strictly paralleled total UGE activity. We suggest a gradual recruitment of individual UGE isoforms into specific roles. UGE2 and UGE4 influence growth and cell wall carbohydrate biosynthesis throughout the plant, UGE3 is specialized for pollen development, and UGE1 and UGE5 might act in stress situations.