Molecular mechanisms controlling kernel development in maize

Maize (Zea mays L.) is one of the most important staple crops globally. Enhancing its yield and quality has become an urgent priority to support the rapidly growing global population. Kernel development, encompassing kernel size, weight, and the accumulation of starch and protein, is a dynamic and intricate process that directly determines grain yield and quality. This developmental program is regulated by complex genetic networks involving a wide array of genes. Over the past decades, numerous genes essential for kernel development have been identified through advances in molecular biology, genetics, and genomics. Despite significant progress, comprehensive reviews focusing specifically on the underlying molecular mechanisms remain limited. In this review, we systematically summarize the cloning and functional characterization of 129 genes associated with kernel development. These genes participate in a wide spectrum of regulatory networks governing kernel development. They function across multiple biological processes, including phytohormone signaling pathways, transcriptional and post-transcriptional regulation, sugar biosynthesis and transport, DNA and protein modifications, ribosome biogenesis, diverse metabolic processes, and molecular transport systems. We also propose future research strategies for identifying additional regulatory genes. These insights contribute to a deeper understanding of the molecular frameworks governing kernel development and offer valuable references for the genetic improvement of maize through the pyramiding of elite alleles related to kernel traits.