The ZmmiR169o/ZmNF-YA13 module orchestrates maize kernel texture by fine-tuning starch biosynthesis and endosperm architecture.

Abstract

Background: Kernel texture is a key agronomic trait determining grain quality and storage stability in maize. The ratio of vitreous endosperm is the principal metric for kernel texture, and elucidating the key genes governing its formation is vital for maize breeding. Although microRNAs (miRNAs) play important regulatory roles in seed development, their functions in controlling grain quality traits, especially endosperm texture, remain poorly understood.

Results: Here, we systematically dissect the regulatory role of the ZmmiR169o/ZmNF-YA13 module in maize kernel texture. Our results show that over-expression of ZmmiR169o significantly enhances kernel hardness, whereas over-expression of its target gene ZmNF-YA13 markedly reduces it. Further mechanistic investigation reveals that ZmNF-YA13 directly activates the expression of starch branching enzyme 1 (ZmSBE1), a key gene in starch biosynthesis. This activation alters amylose content, modulates starch granule size and packing pattern, and ultimately affects the proportion of vitreous endosperm and kernel hardness.

Conclusion: Our study unveils a new regulatory pathway in which the ZmmiR169o/ZmNF-YA13 module precisely controls starch composition to determine kernel texture, providing molecular targets for quality oriented maize breeding and novel insights into miRNA mediated regulation of grain quality.