LAUSR

BACKGROUND Armyworm (Mythimna separata) is a destructive herbivore for maize. Balsas teosinte (Zea mays ssp. parviglumis), the direct wild ancestor of cultivated maize, has shown great potential to defend against herbivory. Here, based on armyworm bioassay, we compared responses of teosinte and B73 maize inbred during armyworm attack in their transcriptome profiles to elucidate the gene expression changes involved in teosinte responses to armyworm attack. The goal of this study is to identify novel resistance alleles that could serve as valuable resources for modern maize breeding. RESULTS Our bioassay revealed that armyworm larvae grew less on teosinte than on maize. A follow-up transcriptomic comparison showed more down-regulated genes in maize B73 and similar numbers of up-regulated genes in both genotypes under armyworm attack. The up-regulated genes in teosinte were markedly enriched in MAPK cascade-mediated signaling pathway and phytohormone pathway. Gene ontology and KEGG pathway analysis showed that phytohormones JA, ETH, SA and ABA were actively involved in armyworm resistance of teosinte plants, and so were transcription factors such as MYBs, WRKYs and TIFYs. Interestingly, teosinte also showed highly regulation in three ABA receptor PYLs. Based on differential expression analysis, we identified 30 candidate defense-related genes in teosinte, which belong to 11 gene families and the majority of the genes were up-regulated, while part of them exhibited nonresponsive in maize. CONCLUSION This study demonstrates that teosinte showed more vigorous defense response than maize toward the armyworm attack and might provide beneficial genetic resource to improve pest resistance in cultivated maize. This article is protected by copyright. All rights reserved.