Phytopathology. 2007 Sep;97(9):1094-103. doi: 10.1094/PHYTO-97-9-1094.
ABSTRACT Aflatoxins are carcinogens produced mainly by Aspergillus flavus during infection of susceptible crops such as maize (Zea mays). Previously, embryo proteins from maize genotypes resistant or susceptible to A. flavus infection were compared using proteomics, and resistance-associated proteins were identified. Here, we report the comparison of maize endosperm proteins from five resistant and five susceptible genotypes, and the identification of additional resistance-associated proteins using the same approach. Ten protein spots were upregulated twofold or higher in resistant lines compared with susceptible ones. Peptide sequencing of these proteins identified them as a globulin-2 protein, late embryogenesis abundant proteins (LEA3 and LEA14), a stress-related peroxiredoxin antioxidant (PER1), heat-shock proteins (HSP17.2), a cold-regulated protein (COR), and an antifungal trypsin-inhibitor protein (TI). The gene encoding one such upregulated protein, PER1, was cloned and overexpressed in Escherichia coli. The overexpressed PER1 protein demonstrated peroxidase activity in vitro. In addition, per1 expression was significantly higher in the resistant genotype Mp420 than in the susceptible genotype B73 during the late stage of kernel development, and was significantly induced upon A. flavus infection, suggesting that it may play an important role in enhancing kernel stress tolerance and aflatoxin resistance. The significance of other identified proteins to host resistance and stress tolerance also is discussed.
摘要 黄曲霉毒素是一种主要由黄曲霉菌在感染玉米（Zea mays）等易感作物时产生的致癌物质。此前，曾使用蛋白质组学方法比较了对黄曲霉菌感染具有抗性或敏感性的玉米基因型的胚胎蛋白，并鉴定了与抗性相关的蛋白。在这里，我们报告了使用相同方法比较了来自五个抗性和五个敏感性基因型的玉米胚乳蛋白，并鉴定了其他与抗性相关的蛋白。与敏感性品系相比，抗性品系中有 10 个蛋白斑点的表达上调了两倍或更高。对这些蛋白质的肽测序将它们鉴定为球蛋白-2 蛋白、晚期胚胎丰富蛋白（LEA3 和 LEA14）、与应激相关的过氧化物还原酶抗氧化剂（PER1）、热休克蛋白（HSP17.2）、冷调节蛋白（COR）和抗真菌胰蛋白酶抑制剂蛋白（TI）。其中一种上调蛋白 PER1 的基因被克隆并在大肠杆菌中过表达。体外过表达的 PER1 蛋白具有过氧化物酶活性。此外，在玉米籽粒发育的后期，抗性基因型 Mp420 中的 per1 表达明显高于敏感性基因型 B73，并且在黄曲霉菌感染后明显诱导，表明它可能在增强籽粒应激耐受性和黄曲霉毒素抗性方面发挥重要作用。还讨论了其他鉴定出的蛋白质对宿主抗性和应激耐受性的意义。
