Association analysis of maize stem vascular bundle micro-characteristics with yield components based on micro-CT and identification of related genes

The distribution pattern of vascular bundles and microstructure characteristics significantly impact crop yield. Previous studies have primarily focused on investigating the micro-phenotypic characteristics and genetic regulation of individual internode, neglecting the exploration of the relationship between different internodes. This study, for the first time, comprehensively analyzed multi-scale phenotypic information of stem cross-sections, zones, and vascular bundles in three different internodes (basal third internode, ear internode and highest internode) of 268 inbred maize lines using Micro-computed tomography scanning. Key findings revealed that basal third internode and ear internode exhibited more stable microscopic characteristics than highest internode. Inbred lines with higher numbers of vascular bundle and well-developed inner zone in ear internode exhibited better yield characteristics, particularly in the kernel number per row. Genome-wide association analysis respectively identified 15, 1 and 1 putative candidate genes in basal third internode, ear internode and highest internode. These genes encode a variety of enzymes, such as oxidases, synthetases, ligase enzyme and protein kinases. Notably, Zm00001d042490 may be an important putative candidate gene for The number of vascular bundles in the periphery zone and corn grain traits. This study provides an important theoretical basis and genetic resources for accurately identifying different internode phenotypes of maize stalks, potentially advancing the selection of high-yielding, high-quality maize varieties.