Identification of ZmGLN5, a candidate gene for resistance to Gibberella ear rot in maize.

BACKGROUND: Gibberella ear rot (GER), caused by the fungal pathogen Fusarium graminearum (F. graminearum), severely affects maize yield and grain quality worldwide. Although numerous genetic loci associated with maize resistance to GER have been identified, the functional genes underlying resistance to GER remain largely uncharacterized. METHODS AND RESULTS: In this study, we performed comparative transcriptome analysis using two maize lines with contrasting resistance to GER. Differently expressed genes were mainly involved in defense-related pathway, including phenylpropanoid biosynthesis, glutathione metabolism, flavonoid biosynthesis, and MAPK signaling pathway. By integrating weighted gene co-expression network analysis and meta-quantitative trait loci results, nine candidate genes for maize resistance to GER were identified. Among these candidates, ZmGLN5, which encodes glutamine synthetase 5, was further validated by gene-based association analysis and mutagenesis experiments. An insert/deletion marker was developed based on the natural variation in the first intron of ZmGLN5, and its genetic effect was validated in a panel of 150 maize inbred lines. In addition, ZmGLN5 may also play a regulatory role in kernel number per row and ear length in maize. CONCLUSION: ZmGLN5 has been characterized as a key candidate gene underlying maize resistance to GER. This finding provides valuable genetic resources for improving resistance to GER in maize breeding programs.