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

Abstract

Abstract The development of maize (Zea mays) kernels is a complex physiological process, regulated by many genes in a spatio-temporal manner. However, there remain many unknown regulatory genes involved in maize kernel development. Here, we have identified a gene (ZmZFP2), which encodes a C4HC3-type RING zinc finger protein, that regulates maize kernel weight and size based on the suppression subtractive hybridization from maize endosperm in our previous studies. Through transgenic technology, over-expression of ZmZFP2 resulted in increased kernel weight and size compared to the wild type, while mutation of the gene led to decreased kernel weight and size. Microscopic observation of developing kernels revealed that ZmZFP2 affects the number of endosperm cells and their filling, as well as the starch and protein contents of the kernels. ZmZFP2 shows constitutive expression in various maize tissues. Furthermore, transcriptome analysis revealed that the zmzfp2-ems mutation significantly interfered with multiple biological processes, especially hormone pathways and ubiquitin degradation. Together, ZmZFP2 affects kernel size and weight by influencing endosperm cell number and filling, providing a valuable potential gene for increasing maize yield.