School of Natural and Environmental Sciences, Newcastle University, Newcastle-Upon-Tyne, NE1 7RU, UK.
College of Biotechnology, Misr University for Science and Technology, Giza, Egypt.
Transgenic Res. 2018 Aug;27(4):355-366. doi: 10.1007/s11248-018-0078-x. Epub 2018 May 17.
Plants have co-evolved with a diverse array of pathogens and insect herbivores and so have evolved an extensive repertoire of constitutive and induced defence mechanisms activated through complex signalling pathways. OXI1 kinase is required for activation of mitogen-activated protein kinases (MAPKs) and is an essential part of the signal transduction pathway linking oxidative burst signals to diverse downstream responses. Furthermore, changes in the levels of OXI1 appear to be crucial for appropriate signalling. Callose deposition also plays a key role in defence. Here we demonstrate, for the first time, that OXI1 plays an important role in defence against aphids. The Arabidopsis mutant, oxi1-2, showed significant resistance both in terms of population build-up (p < 0.001) and the rate of build-up (p < 0.001). Arabidopsis mutants for β-1,3-glucanase, gns2 and gns3, showed partial aphid resistance, significantly delaying developmental rate, taking two-fold longer to reach adulthood. Whilst β-1,3-glucanase genes GNS1, GNS2, GNS3 and GNS5 were not induced in oxi1-2 in response to aphid feeding, GNS2 was expressed to high levels in the corresponding WT (Col-0) in response to aphid feeding. Callose synthase GSL5 was up-regulated in oxi1-2 in response to aphids. The results suggest that resistance in oxi1-2 mutants is through induction of callose deposition via MAPKs resulting in ROS induction as an early response. Furthermore, the results suggest that the β-1,3-glucanase genes, especially GNS2, play an important role in host plant susceptibility to aphids. Better understanding of signalling cascades underpinning tolerance to biotic stress will help inform future breeding programmes for enhancing crop resilience.
植物与多种病原体和昆虫食草动物共同进化，因此进化出了广泛的组成型和诱导型防御机制，这些机制通过复杂的信号通路激活。OXI1 激酶是激活丝裂原活化蛋白激酶（MAPK）所必需的，是将氧化爆发信号与各种下游反应联系起来的信号转导途径的重要组成部分。此外，OXI1 水平的变化似乎对适当的信号传递至关重要。胼胝质沉积也在防御中起关键作用。在这里，我们首次证明 OXI1 在抵御蚜虫方面起着重要作用。拟南芥突变体 oxi1-2 在种群积累（p<0.001）和积累速度（p<0.001）方面都表现出显著的抗性。β-1,3-葡聚糖酶的拟南芥突变体 gns2 和 gns3 表现出部分蚜虫抗性，显著延迟发育速度，达到成年期的两倍长。虽然β-1,3-葡聚糖酶基因 GNS1、GNS2、GNS3 和 GNS5 在 oxi1-2 中没有被诱导响应蚜虫取食，但 GNS2 在相应的 WT（Col-0）中以高水平表达响应蚜虫取食。在 oxi1-2 中，几丁质合酶 GSL5 被上调以响应蚜虫。结果表明，oxi1-2 突变体的抗性是通过 MAPKs 诱导胼胝质沉积，从而导致 ROS 诱导作为早期反应。此外，结果表明，β-1,3-葡聚糖酶基因，特别是 GNS2，在宿主植物对蚜虫的易感性中起重要作用。更好地了解耐受生物胁迫的信号级联将有助于为提高作物弹性的未来育种计划提供信息。
