Istituto di Agronomia, Genetica e Coltivazioni erbacee, Università Cattolica del Sacro Cuore, Via Emilia Parmense 84, 29100 Italy.
J Plant Physiol. 2010 Nov 1;167(16):1398-406. doi: 10.1016/j.jplph.2010.05.015. Epub 2010 Jul 21.
Fusarium verticillioides is the causal agent of ear rot in most maize-growing areas of southern Europe. F. verticillioides produces fumonisins commonly found at biologically significant concentrations in maize grain; the molecular interaction between the fungus and the plant is not well known, and little information is currently available about the defense response of maize against F. verticillioides infection. We attempted to identify genes that may be involved in Fusarium ear rot resistance using resistant and susceptible maize genotypes. Kernels of the resistant inbred showed significantly reduced incidence of infection by F. verticillioides, limited amounts of total fumonisin content and reduced fungal growth, as indicated by a lower copy number of β-tubulin 2 and FUM 21 genes of F. verticillioides. Gene expression data were obtained from microarray hybridizations using maize seeds infected with F. verticillioides, by comparing seeds at 0 and 48h after infection. Differentially expressed sequences were identified and classified into 11 functional categories. Most of the differentially expressed genes were assigned to the category "cell rescue, defense and virulence" in both resistant and susceptible maize lines. These genes encode for PR proteins, detoxification enzymes and β-glucosidases. Most of the pathogenesis-related genes were differentially activated after F. veticillioides infection, depending on the resistance level of the maize genotypes. In kernels of the resistant line, the defense-related genes assayed were transcribed at high levels before infection and provided basic defense against the fungus. In the susceptible kernels, the defense-related genes were induced from a basal level, responding specifically to pathogen infection. The qRT-PCR in infected silks showed that PR1, PR5, PRm6 and thaumatin genes had lower expression ratios in the resistant line compared to the susceptible one.
镰刀菌（Fusarium verticillioides）是欧洲南部大部分玉米种植区穗腐病的病原体。F. verticillioides 通常会在玉米籽粒中产生生物意义上浓度较高的伏马菌素；真菌与植物之间的分子相互作用尚未得到很好的认识，目前关于玉米对 F. verticillioides 感染的防御反应的信息很少。我们试图使用抗感玉米基因型来鉴定可能参与镰刀菌穗腐病抗性的基因。抗性自交系的籽粒显示出受 F. verticillioides 感染的发生率显著降低，总伏马菌素含量有限，真菌生长受到限制，这表明 F. verticillioides 的β-微管蛋白 2 和 FUM 21 基因的拷贝数较低。通过比较感染 F. verticillioides 后 0 和 48 小时的玉米种子，从微阵列杂交获得的基因表达数据。鉴定了差异表达序列，并将其分为 11 个功能类别。在抗性和易感玉米系中，大多数差异表达基因都被分配到“细胞拯救、防御和毒力”类别。这些基因编码 PR 蛋白、解毒酶和β-葡萄糖苷酶。在 F. veticillioides 感染后，大多数与发病相关的基因根据玉米基因型的抗性水平而被差异激活。在抗性系的籽粒中，在感染前，防御相关基因被高水平转录，并为真菌提供了基本的防御。在易感的籽粒中，防御相关基因从基础水平被诱导，特异性地对病原体感染做出反应。在感染的花丝中进行的 qRT-PCR 显示，与易感系相比，PR1、PR5、PRm6 和几丁质酶基因在抗性系中的表达比率较低。
