植物系统性获得抗病性的产生机理和途径

MECHANISMS AND PATHWAYS OF PLANT SYSTEMIC ACQUIRED RESISTANCE

坏死型病原物侵染或某些生化制剂诱导处理后,植株未受侵染或处理部位产生对随后病原物侵染的抗性,称为植物系统性获得抗性(systemic acquired resistance,SAR)。SAR具有抗性表现系统、持久、抗病对象广谱三大特点。坏死型病原物侵染或某些生化制剂处理后,植株受处理部位迅速产生系统性信号,经韧皮部传导到未侵染或处理部位,诱发SAR基因表达。水杨酸是诱发SAR的系统性信号之一。此外,上部非处理部位处于敏化状态(conditioning或sensitizing),能更迅速有效地产生针对挑战接种病原物的防卫反应。敏化状态产生依赖于SA对防卫反应信号放大和强化(signal potentiation)机制。SAR信号传导途径错综复杂,通过诱变筛选获取了一系列SAR突变体,已克隆数个编码SAR信号传导途径成分的基因,并分析了其产物功能。

The mechanism and pathways of plant systemic acquired was reviewed. After plant is inoculated with a necrotizing pathogen or treated with some chemicals, the uninoculated or untreated parts of the plant will demonstrate resistance to the infection of a second pathogen, which is called plant systemic acquired resistance (SAR). SAR is systemic, long lasting resistance to a wide range of pathogens. The inoculated or treated parts immediately produce systemic signal, which is translocated to the uninoculated or untreated parts of the plant, and induce the expression of SAR genes. Salicylic acid (SA) is one of the signal molecules inducing SAR. When plants are pretreated with a necrotizing pathogen of a SAR activator, the upper untreated leaves turn into conditioning or sensitizing situation. They react more rapidly and more efficiently to a challenge infection with a virulent pathogen. SA in the sensitized tissue activates the pathogen-dependent fine control mechanism, which potentiates the nonspecific pathogen signal, and activates nonspecific defense response mechanisms, then makes it show SAR. The signal transduction pathway of SAR is complicated. A series of SAR mutants have been selected, several genes encoding components of SAR signal transduction pathway have been cloned, and their functions were analyzed in several laboratories.