Chen Chao-Wen, Yang Yun-Wei, Lur Hur-Sheng, Tsai Yeou-Guang, Chang Men-Chi
Department of Agronomy, National Taiwan University, Taipei, ROC.
Plant Cell Physiol. 2006 Jan;47(1):1-13. doi: 10.1093/pcp/pci216. Epub 2005 Nov 18.
Plant roots retain developmental plasticity and respond to environmental stresses or exogenous plant growth regulators by undergoing profound morphological and physiological alteration. In this study, we investigated the effects of exogenous ABA on root growth and development in Taichung native 1 (TN1) rice. Exogenous application of 10 microM ABA leads to swelling, root hair formation and initiation of lateral root primodia in the tips of young, seminal rice roots. Cortex cells increased in size and were irregularly shaped. ABA treatment significantly increased 2, 3, 5-triphenyl tetrazolium chloride (TTC) reductase ability in the root tips and the exudation rate of xylem sap. In addition, the K(+) ion content in xylem sap increased nearly 2-fold, but not that of Ca(2+) or Mg(2+). Analysis of proteins expressed in the root tips identified several ABA-induced or -repressed proteins, including actin depolymerization factor (ADF), late embryo abundant protein (LEA), putative steroid membrane-binding protein, ferredoxin thionine reductase and calcium-binding protein. The effects of ABA on root morphogenesis change were Ca(2+) dependent and required the participation of calmodulin and de novo protein synthesis. A model is presented that illustrates how ABA acts through a potential cellular and signal transduction mechanism to induce morphological and physiological changes in rice roots.
植物根系具有发育可塑性，通过经历深刻的形态和生理变化来响应环境胁迫或外源植物生长调节剂。在本研究中，我们研究了外源脱落酸（ABA）对台中本地1号（TN1）水稻根系生长发育的影响。外源施加10微摩尔ABA会导致水稻幼嫩种子根根尖肿胀、形成根毛并引发侧根原基。皮层细胞体积增大且形状不规则。ABA处理显著提高了根尖中2,3,5-三苯基氯化四氮唑（TTC）还原酶活性以及木质部汁液的渗出率。此外，木质部汁液中的钾离子含量增加了近2倍，但钙离子或镁离子含量未增加。对根尖中表达的蛋白质进行分析，鉴定出了几种ABA诱导或抑制的蛋白质，包括肌动蛋白解聚因子（ADF）、胚胎后期丰富蛋白（LEA）、假定的类固醇膜结合蛋白、铁氧还蛋白硫氧还蛋白还原酶和钙结合蛋白。ABA对根系形态发生变化的影响依赖于钙离子，并且需要钙调蛋白和从头蛋白质合成的参与。本文提出了一个模型，阐述了ABA如何通过潜在的细胞和信号转导机制诱导水稻根系的形态和生理变化。
