Department of Biochemistry and Molecular Biology, Mississippi State University, Mississippi State, MS 39762, USA.
J Chem Ecol. 2010 Feb;36(2):179-91. doi: 10.1007/s10886-010-9752-z. Epub 2010 Feb 11.
This study was conducted to determine if constitutive levels of jasmonic acid (JA) and other octadecanoid compounds were elevated prior to herbivory in a maize genotype with documented resistance to fall armyworm (Spodoptera frugiperda) and other lepidopteran pests. The resistant inbred Mp708 had approximately 3-fold higher levels of jasmonic acid (JA) prior to herbivore feeding than the susceptible inbred Tx601. Constitutive levels of cis-12-oxo-phytodienoic acid (OPDA) also were higher in Mp708 than Tx601. In addition, the constitutive expression of JA-inducible genes, including those in the JA biosynthetic pathway, was higher in Mp708 than Tx601. In response to herbivory, Mp708 generated comparatively higher levels of hydrogen peroxide, and had a greater abundance of NADPH oxidase transcripts before and after caterpillar feeding. Before herbivore feeding, low levels of transcripts encoding the maize insect resistance cysteine protease (Mir1-CP) and the Mir1-CP protein were detected consistently. Thus, Mp708 appears to have a portion of its defense pathway primed, which results in constitutive defenses and the ability to mount a stronger defense when caterpillars attack. Although the molecular mechanisms that regulate the constitutive accumulation of JA in Mp708 are unknown, it might account for its enhanced resistance to lepidopteran pests. This genotype could be valuable in studying the signaling pathways that maize uses to response to insect herbivores.
本研究旨在确定在具有抗秋粘虫（Spodoptera frugiperda）和其他鳞翅目害虫记录的玉米基因型中，茉莉酸（JA）和其他十八碳烷酸化合物的组成水平是否在取食前升高。具有抗性的近交系 Mp708 在取食前的茉莉酸（JA）水平比易感近交系 Tx601 高约 3 倍。Mp708 中的顺式-12-氧-植二烯酸（OPDA）组成水平也高于 Tx601。此外，JA 诱导基因的组成型表达，包括 JA 生物合成途径中的基因，在 Mp708 中比 Tx601 更高。对取食的反应，Mp708 产生相对较高水平的过氧化氢，并且在毛毛虫取食前后 NADPH 氧化酶转录本的丰度更高。在取食前，一直检测到编码玉米抗虫半胱氨酸蛋白酶（Mir1-CP）和 Mir1-CP 蛋白的低水平转录本。因此，Mp708 似乎已经启动了其防御途径的一部分，这导致其具有组成型防御能力，并在毛毛虫攻击时能够发动更强的防御。尽管调节 Mp708 中 JA 组成型积累的分子机制尚不清楚，但它可能解释了其对鳞翅目害虫增强的抗性。这种基因型在研究玉米用于应对昆虫取食者的信号通路方面可能具有价值。
