ZmPRX38 is required for improving stalk strength and yield in maize

Stalk lodging is a major problem in maize production, usually causing significant yield losses due to weak stalk strength. Understanding the genetic basis of stalk strength is crucial for improving maize lodging resistance. In this study, we identify 31 quantitative trait loci (QTLs) related to maize stalk strength and clone ZmPRX38 (encoding peroxidase 38) responsible for a hotspot QTL region of stalk strength. ZmPRX38 is highly expressed in maize stalk during vegetative growth stage, and its protein is localized in the cell membrane, cytoplasm and apoplast. Knockout of ZmPRX38 decreases stalk strength and yield in maize, while overexpressing ZmPRX38 increases stalk strength and yield. ZmPRX38 in phenylpropanoid pathway is involved in the biosynthesis of guaiacyl lignin, p-hydroxy-phenyl lignin, and syringyl lignin. Additionally, we identify a favorable haplotype of ZmPRX38, which enhances stalk strength, containing three loci distributed in the 5' untranslated region (UTR), exon 1, and 3'UTR of ZmPRX38, respectively. Although 91.46% of maize natural lines contain this favorable haplotype, most of the Huang-gai (HG) lines, a backbone maize germplasm, contain the unfavorable haplotypes. Therefore, targeted improvement of ZmPRX38 by editing unfavorable haplotypes may be an effective strategy for increasing maize stalk strength, thereby improving maize lodging resistance and yield.