Rajasekhar VK, Lamb C, Dixon RA
Plant Biology Division, Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401 (V.K.R., R.A.D.).
Plant Physiol. 1999 Aug;120(4):1137-46. doi: 10.1104/pp.120.4.1137.
Soybean (Glycine max) cv Williams 82 suspension cultures exhibit an oxidative burst approximately 3 h after challenge with Pseudomonas syringae pv glycinea (Psg) harboring the avrA (avirulence) gene. Pretreatment with the tyrosine (Tyr) kinase inhibitor herbimycin A or the serine/threonine kinase inhibitor K252a abolished the burst and subsequent induction of glutathione S-transferase. However, imposition of a 45-min rest period between pathogen challenge and subsequent addition of the kinase inhibitors resulted in escape from inhibition by herbimycin A, whereas inhibition by K252a persisted. Suramin, a G-protein inhibitor, inhibited the burst if added up to 90 min after pathogen challenge. The burst was also induced by the ion channel generator amphotericin B, and this induction was sensitive to suramin and K252a. Conversely, the ion channel blocker anthracene-9-carboxylate inhibited the Psg:avrA-induced burst. Psg:avrA rapidly induced Tyr phosphorylation of several proteins, and this was inhibited by herbimycin A or anthracene 9-carboxylic acid. These data suggest that the activation of ion channels is followed by an upstream Tyr kinase before the serine/threonine kinase-dependent steps in the signal pathway leading to the oxidative burst. Psg:avrA-dependent induction of phenylalanine ammonia-lyase was not inhibited by herbimycin or suramin, suggesting the operation of different signal pathways for the oxidative burst and phenylpropanoid-derived defense responses.
大豆（Glycine max）品种Williams 82悬浮培养物在用携带avrA（无毒）基因的大豆丁香假单胞菌（Psg）激发后约3小时会出现氧化爆发。用酪氨酸（Tyr）激酶抑制剂除莠霉素A或丝氨酸/苏氨酸激酶抑制剂K252a预处理可消除爆发以及随后谷胱甘肽S-转移酶的诱导。然而，在病原体激发与随后添加激酶抑制剂之间设置45分钟的静止期，会导致细胞逃脱除莠霉素A的抑制，而K252a的抑制作用仍然存在。苏拉明，一种G蛋白抑制剂，如果在病原体激发后90分钟内添加，会抑制氧化爆发。离子通道诱导剂两性霉素B也可诱导氧化爆发，并且这种诱导对苏拉明和K252a敏感。相反，离子通道阻滞剂蒽-9-羧酸盐可抑制Psg:avrA诱导的氧化爆发。Psg:avrA可迅速诱导几种蛋白质的酪氨酸磷酸化，而这会被除莠霉素A或蒽-9-羧酸抑制。这些数据表明，在导致氧化爆发的信号通路中，在丝氨酸/苏氨酸激酶依赖性步骤之前，离子通道的激活之后是上游酪氨酸激酶的作用。Psg:avrA依赖性苯丙氨酸解氨酶的诱导不受除莠霉素或苏拉明的抑制，这表明氧化爆发和苯丙烷类衍生防御反应存在不同的信号通路。
