ZmZFP2 encoding a C4HC3-type RING zinc finger protein regulates kernel size and weight in maize

The development of maize (Zea mays) kernels is a complex physiological process regulated by numerous genes in a spatially and temporally coordinated manner. However, many regulatory genes involved in this process remain unidentified. In this study, we identified ZmZFP2, a gene encoding a C4HC3-type RING zinc finger protein, which regulates kernel size and weight. This discovery was based on suppression subtractive hybridization from maize endosperm in our previous research. We further investigated the role of ZmZFP2 in regulating kernel development. The zmzfp2-ems mutant exhibited significantly reduced kernel size and weight, accompanied by fewer endosperm cells and altered starch and protein accumulation. CRISPR/Cas9-mediated knockouts and overexpression lines confirmed that ZmZFP2 positively regulates kernel size and weight, with overexpression leading to increased kernel size and weight. Transcriptome analysis revealed that ZmZFP2 regulates genes involved in zeatin biosynthesis, starch metabolism, and protein processing, further supporting its role in kernel development. Additionally, ZmZFP2 was shown to interact with the transcription factor ZmEREB98, implicating it in the gene regulatory network during grain filling. Together, these findings demonstrate that ZmZFP2 is a key regulator of maize kernel size and weight, functioning through its E3 ubiquitin ligase activity and interactions with various metabolic pathways. This study provides novel insights into the genetic regulation of kernel development and presents potential strategies for improving maize yield and quality.