Table_3_Maize kernel metabolome involved in resistance to fusarium ear rot and fumonisin contamination.xlsx

Fusarium verticillioides poses a threat to worldwide maize production due to its ability to infect maize kernel and synthesize fumonisins that can be accumulated above safety levels for humans and animals. Maize breeding has been proposed as key tool to decrease kernel contamination with fumonisins, but metabolic studies complementary to genomic approaches are necessary to disclose the complexity of maize resistance. An untargeted metabolomic study was proposed using inbreds genetically related but with contrasting levels of resistance in order to uncover pathways implicated in resistance to Fusarium ear rot (FER) and fumonisin contamination in the maize kernel and to look for possible biomarkers. Metabolite determinations were performed in kernels collected at 3 and 10 days after inoculation with F. verticillioides (dat). Discriminant metabolites between resistant and susceptible RILs were rather found at 10 than 3 dat, although metabolite differences at later stages of colonization could be driven by subtle variations at earlier stages of infection. Within this context, differences for membrane lipid homeostasis, methionine metabolism, and indolacetic acid conjugation seemed highly relevant to distinguish between resistant and susceptible inbreds, confirming the polygenic nature of resistance to FER and fumonisin contamination in the maize kernels. Nevertheless, some specific metabolites such as the polyamine spermidine and/or the alkaloid isoquinoline seemed to be promising indirect selection traits to improve resistance to FER and reduce fumonisin accumulation. Therefore, in vitro and in vivo experiments will be necessary to validate the inhibitory effects of these compounds on fumonisins biosynthesis.

轮枝镰孢菌（Fusarium verticillioides）可侵染玉米籽粒并合成伏马菌素（fumonisins），当该毒素在籽粒中积累量超出人畜安全阈值时，会对全球玉米生产造成严重威胁。玉米育种被认为是降低玉米籽粒伏马菌素污染的核心手段，但要阐明玉米抗病机制的复杂性，需开展与基因组学研究相辅相成的代谢组学研究。本研究采用遗传背景相似但抗病性存在显著差异的玉米自交系开展非靶向代谢组学研究，旨在揭示玉米籽粒抗穗腐病（Fusarium ear rot, FER）及伏马菌素污染的相关通路，并筛选潜在的生物标志物。本研究在接种轮枝镰孢菌后第3天和第10天（days after inoculation, dat）采集玉米籽粒，进行代谢物检测。抗病与感病重组自交系（Recombinant Inbred Lines, RILs）间的差异代谢物主要在接种后第10天被检测到，而非第3天；不过病原菌定殖后期的代谢物差异，可能由感染早期的细微代谢变化所驱动。在此背景下，膜脂稳态、甲硫氨酸代谢及吲哚乙酸结合通路的差异，可有效区分抗病与感病玉米自交系，这也证实了玉米籽粒抗穗腐病及伏马菌素污染的抗病性属于多基因调控性状。不过，部分特定代谢物——如多胺类物质亚精胺（spermidine）及生物碱异喹啉（isoquinoline）——有望作为间接筛选性状，用于改良玉米抗穗腐病能力并降低伏马菌素积累。因此，需开展体外及体内实验，以验证上述化合物对伏马菌素生物合成的抑制作用。