Chitinase-Like Protein CTL1 Plays a Role in Altering Root System Architecture in Response to Multiple Environmental Conditions
Chitinase-Like Protein CTL1 Plays a Role in Altering Root System Architecture in Response to Multiple Environmental Conditions
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DOI：
10.1104/pp.109.149849
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发表时间：
2010-02-01
期刊：
影响因子：
7.4
通讯作者：
Bush, Daniel R.
中科院分区：
文献类型：
--
作者：
Hermans, Christian;Porco, Silvana;Bush, Daniel R.
植物根系结构对养分有效性的变化有高度的反应。然而，调控根系适应环境变化的分子机制尚不清楚。对甲基磺酸乙酯诱变的拟南芥（Arabidopsis thaliana）群体进行了对高硝酸盐生长培养基中异常根构反应的筛选。在低至中等硝酸盐浓度下生长时，突变株的生长和根系结构（阴离子改变了根系形态）与野生型植物相似，但在高硝酸盐浓度下，与野生型对照相比，突变株的主根伸长减少，径向膨胀，侧根数量增加，根毛密度增加。高浓度的氯化物和蔗糖诱导了相同的表型。相比之下，黑暗中下胚轴伸长的减少与硝酸盐的有效性无关。定位克隆鉴定出编码几丁质酶相关蛋白的AtCTL1基因的一个点突变，尽管分子和生化分析表明该蛋白不具有几丁质酶活性。基于arm突变对初生根生长的组成效应及其对根构型的条件影响，CTL1似乎在植物生长发育中起着双重作用。我们假设CTL1在决定细胞壁刚性中起作用，并且其活性受到由环境条件触发的途径的差异调节。此外，我们发现纤维素合酶复合体的一些亚基突变体在非允许条件下对根结构产生条件效应，这表明它们在响应变化的环境时也受到差异调节。
Plant root architecture is highly responsive to changes in nutrient availability. However, the molecular mechanisms governing the adaptability of root systems to changing environmental conditions is poorly understood. A screen for abnormal root architecture responses to high nitrate in the growth medium was carried out for a population of ethyl methanesulfonate-mutagenized Arabidopsis (Arabidopsis thaliana). The growth and root architecture of the arm (for anion altered root morphology) mutant described here was similar to wild-type plants when grown on low to moderate nitrate concentrations, but on high nitrate, arm exhibited reduced primary root elongation, radial swelling, increased numbers of lateral roots, and increased root hair density when compared to the wild-type control. High concentrations of chloride and sucrose induced the same phenotype. In contrast, hypocotyl elongation in the dark was decreased independently of nitrate availability. Positional cloning identified a point mutation in the AtCTL1 gene that encodes a chitinase-related protein, although molecular and biochemical analysis showed that this protein does not possess chitinase enzymatic activity. CTL1 appears to play two roles in plant growth and development based on the constitutive effect of the arm mutation on primary root growth and its conditional impact on root architecture. We hypothesize that CTL1 plays a role in determining cell wall rigidity and that the activity is differentially regulated by pathways that are triggered by environmental conditions. Moreover, we show that mutants of some subunits of the cellulose synthase complex phenocopy the conditional effect on root architecture under nonpermissive conditions, suggesting they are also differentially regulated in response to a changing environment.