State Ministry of Education Key Laboratory of Integrated Management of Crop Pests, Nanjing Agricultural University, Nanjing, China.
Plant Biol (Stuttg). 2013 Sep;15(5):841-50. doi: 10.1111/j.1438-8677.2012.00675.x. Epub 2013 May 8.
Recently we showed that the transcription activator AtMYB44 regulates expression of EIN2, a gene essential for ethylene signalling and insect resistance, in Arabidopsis thaliana (Arabidopsis). To link the transactivation with insect resistance, we investigated the wild-type and atmyb44 mutant plants, genetically Complemented atmyb44 (Catmyb44) and AtMYB44-Overexpression Transgenic Arabidopsis (MYB44OTA). We found that AtMYB44 played a critical role in Arabidopsis resistance to the phloem-feeding generalist green peach aphid (Myzus persicae Sulzer) and leaf-chewing specialist caterpillar diamondback moth (Plutella xylostella L.). AtMYB44 was required not only for the development of constitutive resistance but also for the induction of resistance by both herbivorous insects. Levels of constitutive and herbivore-induced resistance were consistent with corresponding amounts of the AtMYB44 protein constitutively produced in MYB44OTA and induced by herbivory in Catmyb44. In both cases, AtMYB44 promoted EIN2 expression to a greater extent in MYB44OTA than in Catmyb44. However, AtMYB44-promoted EIN2 expression was arrested with reduced resistance levels in the EIN2-deficient Arabidopsis mutant ein2-1 and the MYB44OTA ein2-1 hybrid. In the different plant genotypes, only MYB44OTA constitutively displayed phloem-based defences, which are specific to phloem-feeding insects, and robust expression of genes involved in the biosynthesis of glucosinolates, which are the secondary plant metabolites known as deterrents to generalist herbivores. Phloem-based defences and glucosinolate-related gene expression were not detected in ein2-1 and MYB44OTA ein2-1. These results establish a genetic connection between the regulatory role of AtMYB44 in EIN2 expression and the development of Arabidopsis resistance to insects.
最近，我们发现转录激活因子 AtMYB44 调节拟南芥（Arabidopsis）中 EIN2 的表达，EIN2 基因对乙烯信号转导和昆虫抗性至关重要。为了将这种转录激活与昆虫抗性联系起来，我们研究了野生型和 atmyb44 突变体植物、基因互补的 atmyb44（Catmyb44）和 AtMYB44 过表达转基因拟南芥（MYB44OTA）。我们发现 AtMYB44 在拟南芥对韧皮部取食的普通绿桃蚜（Myzus persicae Sulzer）和叶片取食的专食小菜蛾（Plutella xylostella L.）的抗性中发挥了关键作用。AtMYB44 不仅需要组成型抗性的发育，还需要两种取食性昆虫诱导的抗性。组成型和取食诱导抗性的水平与 MYB44OTA 中组成型产生的 AtMYB44 蛋白和 Catmyb44 中取食诱导的 AtMYB44 蛋白相对应。在这两种情况下，AtMYB44 在 MYB44OTA 中比在 Catmyb44 中更能促进 EIN2 的表达。然而，在 EIN2 缺陷型拟南芥突变体 ein2-1 和 MYB44OTA ein2-1 杂种中，AtMYB44 促进 EIN2 表达的能力受到抑制，抗性水平降低。在不同的植物基因型中，只有 MYB44OTA 表现出韧皮部防御，这是专用于韧皮部取食昆虫的防御，以及与硫代葡萄糖苷生物合成相关的基因的强烈表达，硫代葡萄糖苷是作为一般食草动物抑制剂的次生植物代谢物。在 ein2-1 和 MYB44OTA ein2-1 中未检测到韧皮部防御和硫代葡萄糖苷相关基因的表达。这些结果确立了 AtMYB44 在 EIN2 表达中的调节作用与拟南芥对昆虫抗性发展之间的遗传联系。
