UDP-Glucose Pyrophosphorylase is Rate Limiting in Vegetative and Reproductive Phases in Arabidopsis thaliana
UDP-Glucose Pyrophosphorylase is Rate Limiting in Vegetative and Reproductive Phases in Arabidopsis thaliana
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DOI：
10.1093/pcp/pcq057
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发表时间：
2010-06-01
影响因子：
4.9
通讯作者：
Watanabe, Masao
中科院分区：
文献类型：
--
作者：
Park, Jong-In;Ishimizu, Takeshi;Watanabe, Masao
UDP-葡萄糖焦磷酸化酶（UGPase）是UDP-葡萄糖代谢中的重要酶，UDP-葡萄糖是合成碳水化合物细胞壁组分如纤维素和胼胝质的前体。拟南芥基因组含有两个推定的基因编码UGPase，AtUGP 1和AtUGP 2。这些基因在所有器官中都有表达。为了确定UGPase在营养和生殖器官中的作用，我们采用了反向遗传方法，使用T-DNA插入突变体atugp 1和atugp 2。尽管atugp 7和atugp 2单突变体中UGPase活性显著降低，但未观察到正常生长和繁殖的降低。与此相反，atugp 1/atugp 2双突变体显示严重的生长缺陷和雄性不育。在生殖生长期，atugp 1/atugp 2的花药中，花粉母细胞发育正常，但小孢子周围无胼胝质沉积。在纤维素和胼胝质合成途径的后续步骤中的酶编码基因也在双突变体中下调。综上所述，这些结果表明，AtUGP 1和AtUGP 2基因是功能冗余和UGPase活性是必不可少的营养和生殖阶段在拟南芥。重要的是，男性生育能力没有恢复在双敲除突变体的应用外部蔗糖，而营养生长的大小与野生型。与此相反，外部UDP-葡萄糖的应用恢复了双突变体中的雄性育性，这表明与A. thaliana.
UDP-glucose pyrophosphorylase (UGPase) is an important enzyme in the metabolism of UDP-glucose, a precursor for the synthesis of carbohydrate cell wall components, such as cellulose and callose. The Arabidopsis thaliana genome contains two putative genes encoding UGPase, AtUGP1 and AtUGP2. These genes are expressed in all organs. In order to determine the role of UGPase in vegetative and reproductive organs, we employed a reverse genetic approach using the T-DNA insertion mutants, atugp1 and atugp2. Despite a significant decrease in UGPase activity in both the atugp7 and atugp2 single mutants, no decrease in normal growth and reproduction was observed. In contrast, the atugp1/atugp2 double mutant displayed drastic growth defects and male sterility. At the reproductive phase, in the anthers of atugp1/atugp2, pollen mother cells developed normally, but callose deposition around microspores was absent. Genes coding for enzymes at the subsequent steps in the cellulose and callose synthesis pathway were also down-regulated in the double mutant. Taken together, these results demonstrate that the AtUGP1 and AtUGP2 genes are functionally redundant and UGPase activity is essential for both vegetative and reproductive phases in Arabidopsis. Importantly, male fertility was not restored in the double knockout mutant by an application of external sucrose, whereas vegetative growth was comparable in size with that of the wild type. In contrast, an application of external UDP-glucose recovered male fertility in the double mutant, suggesting that control of UGPase in carbohydrate metabolism is different in the vegetative phase as compared with the reproductive phase in A. thaliana.