Apoplastic alterations as a common mechanism to freezing avoidance and growth cessation/dormancy induction through temperature-mediated pectin gelation

质外体改变是通过温度介导的果胶凝胶化避免冷冻和生长停止/休眠诱导的常见机制

• 批准号: 97642-2012
• 负责人: Tanino, Karen
• 金额: $ 1.82万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=545104
• 关键词: Apoplastic; alterations; common; mechanism; freezing

Lack of plant synchrony with the environment is the primary cause of abiotic stress injury resulting in significant economic loss. Plants are stationary organisms and must adapt to their environment in order to survive. Temperature has been a key driver to adaptation throughout plant evolutionary history. However, the mechanism of these thermal adaptations is still not understood. The apoplastic space represents a key region regulating both ice propagation and cell growth. Apoplastic regions are permeability barriers to avoid ice propagation directly into the plant cell through arabinoxylan polymers or Anti-Freeze Proteins. The cell wall fraction is a biphasic structure consisting of cellulose microfibrils held together by a gel-like matrix. This gel-like matrix constitutes up to two-thirds of the cell wall's dry weight (47% of primary cell walls of Populus), and is composed of cross-linking extensin glycoproteins and non-cellulosic polysaccharides including pectins (polygalacturonic acids (PGAs), and rhamnogalacturonan (RG) I and II) and hemicelluloses. Pectins are the major regulatory molecule dictating the porosity of cell walls. The gelation, rigidity and subsequent permeability of the apoplast is dictated by the pectin matrix through Pectin Methyl Esterase (PME) which removes pectin methyl groups, allowing Ca2+ binding to the carboxylate ions and creating calcium cross-linkages. This rigidity and pectic gel formation also influences key cell expansion parameters of water flow and turgor pressure through changes in water permeability. PME's and pectin gelation are dynamic and temperature-sensitive but most of the evidence comes from the food processing literature. Remarkably, there are only a limited number of such studies in plants. This project will address the following overarching hypothesis through 1 Ph.D. student, 1 M.Sc. student and 4 undergraduate summer students: Apoplastic alterations through pectin gelation result in: a) freezing avoidance by reduced ice propagation into the intracellular space, and b) temperature-dependent dormancy induction through reduction of water flow.

缺乏与环境同步的植物同步是造成非生物压力损伤的主要原因，导致经济损失巨大。植物是固定的生物，必须适应其环境才能生存。 温度一直是整个植物进化史适应的关键驱动力。 但是，这些热适应的机制仍然尚不清楚。塑料空间代表调节冰繁殖和细胞生长的关键区域。 塑料区域是渗透性屏障，可以通过阿拉伯素聚合物或抗冻结蛋白直接避免进入植物细胞。细胞壁分数是一种双相结构，由纤维素微纤维组成，由凝胶样基质组成。 这种类似凝胶的基质构成了细胞壁干重的三分之二（占植物的原代细胞壁的47％），由交联的延伸蛋白糖蛋白和非纤维素多糖组成，包括果胶（包括聚半乳酸（PGAS）（PGAS）和Rhammnog Acturonan和Hemellonan和Hemellonan和Hemlonan和Hemlonan和HemloNAn（Rhamlacturonics）和HemloNAn和Hem ii（Rhamnognog）和Hem ii（rhamnoganog）和Hem ii。 果胶是决定细胞壁的孔隙率的主要调节分子。 蛋白质成形体的凝胶化，刚度和随后的渗透性由果胶基质通过果胶甲基酯酶（PME）决定，该基质去除果胶甲基，从而使Ca2+结合羧酸盐离子并产生钙交叉链接。 这种刚性和果胶的形成还通过变化水的渗透性来影响水流量和thergor压力的关键细胞膨胀参数。 PME和果胶凝胶化是动态和温度敏感的，但大多数证据来自食品加工文献。 值得注意的是，植物中只有有限的研究。 该项目将通过1博士学位解决以下总体假设。学生，1 M.Sc.学生和4名本科夏季学生：通过果胶凝胶化的凋亡改变导致：a）通过减少冰的传播到细胞内空间的冰冻回避，b）通过减少水流来诱导温度依赖性休​​眠。