National Institute of Plant Genome Research, New Delhi, India.
PLoS One. 2013 Sep 30;8(9):e76029. doi: 10.1371/journal.pone.0076029. eCollection 2013.
Monoterpenes, which are among the major components of plant essential oils, are known for their ecological roles as well for pharmaceutical properties. Geraniol, an acyclic monoterpene induces cell cycle arrest and apoptosis/senescence in various cancer cells and plants; however, the genes involved in the process and the underlying molecular mechanisms are not well understood. In this study, we demonstrate that treatment of tomato plants with geraniol results in induction of senescence due to a substantial alteration in transcriptome. We have identified several geraniol-responsive protein encoding genes in tomato using suppression subtractive hybridization (SSH) approach. These genes comprise of various components of signal transduction, cellular metabolism, reactive oxygen species (ROS), ethylene signalling, apoptosis and DNA damage response. Upregulation of NADPH oxidase and antioxidant genes, and increase in ROS level after geraniol treatment point towards the involvement of ROS in geraniol-mediated senescence. The delayed onset of seedling death and induced expression of geraniol-responsive genes in geraniol-treated ethylene receptor mutant (Nr) suggest that geraniol-mediated senescence involves both ethylene dependent and independent pathways. Moreover, expression analysis during tomato ripening revealed that geraniol-responsive genes are also associated with the natural organ senescence process.
单萜类化合物是植物精油的主要成分之一,它们不仅具有生态作用,还具有药用特性。香叶醇是一种无环单萜,它能诱导多种癌细胞和植物发生细胞周期停滞和细胞凋亡/衰老;然而,涉及该过程的基因及其潜在的分子机制尚不清楚。在这项研究中,我们证明了香叶醇处理番茄植株会导致转录组发生重大改变,从而诱导衰老。我们使用抑制性消减杂交(SSH)方法在番茄中鉴定了几个香叶醇响应蛋白编码基因。这些基因包括信号转导、细胞代谢、活性氧(ROS)、乙烯信号转导、细胞凋亡和 DNA 损伤反应的各种成分。香叶醇处理后 NADPH 氧化酶和抗氧化基因的上调以及 ROS 水平的增加表明 ROS 参与了香叶醇介导的衰老。在乙烯受体突变体(Nr)中,香叶醇处理后幼苗死亡延迟和香叶醇响应基因的诱导表达表明,香叶醇介导的衰老既涉及乙烯依赖途径,也涉及乙烯非依赖途径。此外,在番茄成熟过程中的表达分析表明,香叶醇响应基因也与自然器官衰老过程有关。