Gurung Sushma, Cohen Michael F, Fukuto Jon, Yamasaki Hideo
Faculty of Science, University of the Ryukyus, Nishihara 903-0213, Japan.
J Amino Acids. 2012;2012:493209. doi: 10.1155/2012/493209. Epub 2012 Sep 11.
Floating ferns of the genus Azolla detach their roots under stress conditions, a unique adaptive response termed rapid root abscission. We found that Azolla pinnata plants exhibited dose-dependent rapid root abscission in response to the polyamines spermidine and spermine after a substantial time lag (>20 min). The duration of the time lag decreased in response to high pH and high temperature whereas high light intensity increased the time lag and markedly lowered the rate of abscission. The oxidation products of polyamines, 1,3-diaminopropane, β-alanine and hydrogen peroxide all failed to initiate root abscission, and hydroxyethyl hydrazine, an inhibitor of polyamine oxidase, did not inhibit spermine-induced root abscission. Exposure of A. pinnata to the polyamines did not result in detectable release of NO and did not affect nitrite-dependent NO production. The finding of polyamine-induced rapid root abscission provides a facile assay for further study of the mode of action of polyamines in plant stress responses.
满江红属的漂浮蕨类植物在胁迫条件下会使其根脱落，这是一种独特的适应性反应，称为快速根脱落。我们发现，经过相当长的时间延迟（>20分钟）后，羽叶满江红植株对多胺亚精胺和精胺表现出剂量依赖性的快速根脱落。时间延迟的持续时间随着高pH值和高温而减少，而高光强度则增加了时间延迟并显著降低了脱落速率。多胺的氧化产物1,3-二氨基丙烷、β-丙氨酸和过氧化氢均未能引发根脱落，多胺氧化酶抑制剂羟乙基肼也未抑制精胺诱导的根脱落。将羽叶满江红暴露于多胺中不会导致可检测到的一氧化氮释放，也不会影响亚硝酸盐依赖性一氧化氮的产生。多胺诱导的快速根脱落这一发现为进一步研究多胺在植物应激反应中的作用模式提供了一种简便的测定方法。
