Maize kernels: Non Inoculated vs. Inoculated with Fusarium verticillioides

Fusarium verticillioides is a detrimental fungus that can contaminate maize grains with mycotoxins that are harmful to human and animal health. Breeding and growing resistant genotypes is one alternative to reduce contamination and subsequent production of mycotoxins by this fungus. However, little is known about the resistant mechanism relevant to breeding in this pathosystem. Therefore, our aim was to identify genes and metabolites that may be related to Fusarium ear rot resistance using resistant and susceptible maize inbreds. Kernels of the resistant inbred showed significantly reduced disease severity, and reduced levels of total fumonisin and ergosterol content compared with the susceptible one. Gene expression data were obtained from microarray hybridizations using F. verticillioides inoculated and non inoculated maize kernels. Differentially expressed sequences were identified and classified into 36 functional categories. Most of the differentially expressed genes were assigned to the categories “protein, RNA, DNA, stress, transport, signaling and cell metabolism”. These genes encode for PR proteins, detoxification and primary metabolism enzymes. Fungal inoculation did not produce considerable changes in gene expression and metabolites in the resistant L4637 inbred, probably due to a preformed or constitutive resistance mechanism. Defense-related genes were induced or repressed in kernels of the susceptible inbred L4674, responding specifically to the pathogen infection. The qRT-PCR in infected silks showed that glucanase, lipid transfer, xylanase inhibitor, PR1 and 26S proteosome transcripts had higher expression ratios in the susceptible line compared to the resistant one in response to fungal infection. Through this study, a global view of differential genes expressed and metabolites concentration during resistance and susceptibility to F. verticillioides inoculation has been obtained, giving additional information about the mechanisms and pathways conferring resistance to this important disease in maize. Global view of differential genes expressed during resistance and susceptibility to F. verticillioides inoculation. Two maize inbred lines : one resistant (L4637) and one susceptible (L4674) to F. verticillioides infection. Two-condition experiment, Inoculated (I) vs. non-inoculated (NI) lines. Biological replicates: 3 . One replicate per array.

轮状镰刀菌（Fusarium verticillioides）是一种有害真菌，可侵染玉米籽粒并产生对人畜健康具有危害的真菌毒素（mycotoxin）。育种并种植抗病基因型是减少该真菌侵染与后续真菌毒素产生的有效途径之一。然而，当前对于该病害系统（pathosystem）中与育种相关的抗病机制仍知之甚少。因此，本研究旨在利用抗病与感病玉米自交系，筛选与玉米穗腐病（Fusarium ear rot）抗性相关的基因与代谢物。抗病自交系的籽粒相较于感病自交系，病害严重度显著降低，总伏马毒素（fumonisin）与麦角固醇（ergosterol）含量也显著下降。基因表达数据通过微阵列（microarray）杂交获得，实验材料为接种轮状镰刀菌与未接种的玉米籽粒。研究人员鉴定得到差异表达序列，并将其划分为36个功能类别。绝大多数差异表达基因被归类至“蛋白质、RNA、DNA、胁迫、转运、信号转导与细胞代谢”等类别。这些基因编码病程相关蛋白（PR proteins，PR蛋白）、解毒酶与初级代谢酶。真菌接种并未在抗病自交系L4637中引发显著的基因表达与代谢物变化，这可能归因于其预先形成的组成型抗病机制。而在感病自交系L4674的籽粒中，抗病相关基因被诱导或抑制，以特异性响应病原菌侵染。对受侵染花丝的实时定量聚合酶链反应（qRT-PCR, quantitative real-time polymerase chain reaction）检测显示，相较于抗病自交系，感病自交系在响应真菌侵染时，葡聚糖酶（glucanase）、脂质转运蛋白（lipid transfer）、木聚糖酶抑制剂（xylanase inhibitor）、PR1以及26S蛋白酶体（26S proteosome）转录本的表达丰度更高。本研究明确了轮状镰刀菌接种后，玉米抗病与感病自交系中差异表达基因与代谢物的全局表达谱，为解析玉米抗该重要病害的机制与通路提供了新的科学依据。本数据集聚焦轮状镰刀菌接种后玉米抗病与感病过程中的差异表达基因全局图谱。实验材料为两个玉米自交系：抗轮状镰刀菌侵染的自交系L4637，以及感病自交系L4674。采用双处理实验设计：接种组（Inoculated, I）与未接种组（non-inoculated, NI）。生物学重复数为3，每个微阵列对应一个生物学重复。