Woldemariam Melkamu G, Ahern Kevin, Jander Georg, Tzin Vered
a Biology Department , School of Science, The College of New Jersey , Ewing Township , NJ , USA.
b Boyce Thompson Institute , Ithaca , NY , USA.
Plant Signal Behav. 2018 Jan 2;13(1):e1422462. doi: 10.1080/15592324.2017.1422462. Epub 2018 Jan 17.
Feeding by Spodoptera exigua (beet armyworm) larvae on Zea mays (maize) induces expression of 9-lipoxygenases to a greater extent than 13-lipoxygenases. Whereas 13-lipoxygenases have an established role in the synthesis of jasmonates that serve as defense signaling molecules in many plant species, relatively little is known about the role of 9-lipoxygenases in herbivore defense. Phylogenetic analysis of lipoxygenases from maize inbred lines B73 and W22 shows that, although most Lox genes are present in both lines, Lox12, a 9-lipoxygenase that has been implicated in fungal defense, is truncated and unlikely to encode a functional protein in W22. Two independent Mutator transposon insertions in another 9-lipoxygenase, Lox4, caused improved S. exigua growth on the mutant lines relative to wildtype W22. This observation suggests a function in herbivore defense for metabolic products downstream of maize Lox4, either through direct toxicity or a perhaps an as yet unknown signaling function.
甜菜夜蛾幼虫取食玉米会比13-脂氧合酶更大程度地诱导9-脂氧合酶的表达。虽然13-脂氧合酶在茉莉酸合成中具有既定作用，茉莉酸在许多植物物种中作为防御信号分子，但关于9-脂氧合酶在草食动物防御中的作用知之甚少。对玉米自交系B73和W22中的脂氧合酶进行系统发育分析表明，尽管大多数Lox基因在两个品系中都存在，但Lox12（一种与真菌防御有关的9-脂氧合酶）在W22中被截断，不太可能编码功能性蛋白质。另一种9-脂氧合酶Lox4中的两个独立的Mutator转座子插入导致相对于野生型W22，甜菜夜蛾在突变品系上的生长得到改善。这一观察结果表明，玉米Lox4下游的代谢产物在草食动物防御中具有功能，要么通过直接毒性，要么可能通过一种尚未知晓的信号功能。
