TRICHOME BIREFRINGENCE and Its Homolog AT5G01360 Encode Plant-Specific DUF231 Proteins Required for Cellulose Biosynthesis in Arabidopsis
TRICHOME BIREFRINGENCE and Its Homolog AT5G01360 Encode Plant-Specific DUF231 Proteins Required for Cellulose Biosynthesis in Arabidopsis
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DOI：
10.1104/pp.110.153320
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发表时间：
2010-06-01
期刊：
影响因子：
7.4
通讯作者：
Scheible, Wolf-Ruediger
中科院分区：
文献类型：
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作者：
Bischoff, Volker;Nita, Silvia;Scheible, Wolf-Ruediger
拟南芥（Arabidopsis thaliana）毛状体双折射（tbr）突变体严重减少了毛状体中的结晶纤维素，但TBR的分子本质是未知的。我们确定TBR属于植物特异性DUF 231结构域基因家族，该家族包括拟南芥中46个未知功能的成员。这些基因具有另一个植物特异性结构域，称为TBL结构域，其包含从一些酯酶/脂肪酶已知的保守GDSL基序。TBR和TBR样3（TBL 3）分别与初级和次级纤维素合成酶（CESA）基因在转录上协调。tbr和tbl 3突变体分别在毛状体和茎中保持较低水平的结晶纤维素，并改变了果胶组成，这些组织通常被认为主要含有次生壁结晶纤维素。相反，在黄化的tbr和tbl 3下胚轴中，两种突变体的初生壁纤维素水平保持不变，而酯化果胶的量减少，果胶甲酯酶活性增加。此外，黄化的tbr下胚轴长度减少，表皮细胞肿胀，这是用纤维素合成抑制剂处理的原代cesa突变体或野生型的表型特征。两者合计，我们表明，两个TBL基因有助于次生壁纤维素的合成和沉积，大概是通过影响果胶聚合物的酯化状态。
The Arabidopsis (Arabidopsis thaliana) trichome birefringence (tbr) mutant has severely reduced crystalline cellulose in trichomes, but the molecular nature of TBR was unknown. We determined TBR to belong to the plant-specific DUF231 domain gene family comprising 46 members of unknown function in Arabidopsis. The genes harbor another plant-specific domain, called the TBL domain, which contains a conserved GDSL motif known from some esterases/lipases. TBR and TBR-like3 (TBL3) are transcriptionally coordinated with primary and secondary CELLULOSE SYNTHASE (CESA) genes, respectively. The tbr and tbl3 mutants hold lower levels of crystalline cellulose and have altered pectin composition in trichomes and stems, respectively, tissues generally thought to contain mainly secondary wall crystalline cellulose. In contrast, primary wall cellulose levels remain unchanged in both mutants as measured in etiolated tbr and tbl3 hypocotyls, while the amount of esterified pectins is reduced and pectin methylesterase activity is increased in this tissue. Furthermore, etiolated tbr hypocotyls have reduced length with swollen epidermal cells, a phenotype characteristic for primary cesa mutants or the wild type treated with cellulose synthesis inhibitors. Taken together, we show that two TBL genes contribute to the synthesis and deposition of secondary wall cellulose, presumably by influencing the esterification state of pectic polymers.