The thick aleurone1 Gene Encodes a NOT1 Subunit of the CCR4-NOT Complex and Regulates Cell Patterning in Endosperm

Area of Science:

• Plant genetics
• Developmental biology
• Maize endosperm development

Background:

• The maize thick aleurone1 (thk1-R) mutant exhibits multiple aleurone layers and arrested embryogenesis.
• Previous research suggested thk1 acts downstream of defective kernel1 (dek1) in aleurone cell fate regulation.
• The original thk1-R mutant's large deletion hindered precise gene identification.

Purpose of the Study:

• To identify the causal gene in maize thk1 mutants.
• To elucidate the function of THK1 in endosperm development and cell fate.
• To understand THK1's role within the DEK1 regulatory pathway.

Main Methods:

• Ethyl methanesulfonate mutagenesis to generate new alleles.
• RNA sequencing of developing endosperm to identify differentially expressed genes.
• Gene editing to confirm gene identity and function.
• Transcriptomic analysis to assess THK1's regulatory targets.

Main Results:

• New thk1 alleles were generated, and gene editing confirmed THK1 identity.
• THK1 encodes a homolog of NEGATIVE ON TATA-LESS1, a scaffold protein for a conserved regulatory complex.
• Maize possesses a duplicate locus, thick aleurone-like1, potentially mitigating thk1 mutant phenotypes.
• Transcriptomic data revealed THK1 regulates cell division, signaling, differentiation, and metabolism.

Conclusions:

• THK1 is a crucial gene for maize endosperm development and aleurone cell fate.
• THK1 functions within the DEK1 regulatory network, providing a new component for understanding endosperm patterning.
• The conserved nature of the THK1-associated complex highlights its fundamental role in eukaryotic gene regulation.