NAKED ENDOSPERM1, NAKED ENDOSPERM2, and OPAQUE2 interact to regulate gene networks in maize endosperm development

Area of Science:

• Plant Molecular Biology
• Maize Genetics
• Transcriptional Regulation

Background:

• NAKED ENDOSPERM1 (NKD1), NKD2, and OPAQUE2 (O2) are key transcription factors in maize (Zea mays) endosperm.
• These factors are crucial for cell patterning and nutrient storage, but their complex regulatory interrelationships are not fully understood.

Purpose of the Study:

• To investigate the intricate regulatory interactions among NKD1, NKD2, and O2 in coregulating gene networks.
• To elucidate their dynamic roles during the transition from cellular development to nutrient accumulation in maize endosperm.

Main Methods:

• Development of homozygous lines for all combinations of nkd1, nkd2, and o2 mutants and wild-type genes.
• Phenotypic analysis of diverse genotypes.
• Gene network analysis and Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq).

Main Results:

• Diverse phenotypes and gene interactions affecting cell patterning, starch, and storage proteins were observed across 8 genotypes.
• NKD1, NKD2, and O2 dynamically regulate a hierarchical gene network, shifting from directing cellular development to promoting nutrient biosynthesis and storage.
• O2 decreases accessibility of NKD1/NKD2 target sites, while NKD1/NKD2 increase accessibility of O2 target sites, indicating dynamic regulatory landscape control.

Conclusions:

• NKD1, NKD2, and O2 interactions dynamically shape the hierarchical gene network and regulatory landscape.
• These transcription factors orchestrate the critical transition from cellular development to grain filling in maize endosperm.