Maize (Zea mays) thick aleurone1 (thk1-R) mutants form multiple aleurone layers in the endosperm and have arrested embryogenesis. Prior studies suggest that thk1 functions downstream of defective kernel1 (dek1) in a regulatory pathway that controls aleurone cell fate and other endosperm traits. The original thk1-R mutant contained an ~2-Mb multigene deletion, which precluded identification of the causal gene. Here, ethyl methanesulfonate mutagenesis produced additional alleles, and RNA sequencing from developing endosperm was used to identify a candidate gene based on differential expression compared with the wild-type progenitor. Gene editing confirmed the gene identity by producing mutant alleles that failed to complement existing thk1 mutants and that produced multiple-aleurone homozygous phenotypes. Thk1 encodes a homolog of NEGATIVE ON TATA-LESS1, a protein that acts as a scaffold for the CARBON CATABOLITE REPRESSION4-NEGATIVE ON TATA-LESS complex. This complex is highly conserved and essential in all eukaryotes for regulating a wide array of gene expression and cellular activities. Maize also harbors a duplicate locus, thick aleurone-like1, which likely accounts for the ability of thk1 mutants to form viable cells. Transcriptomic analysis indicated that THK1 regulates activities involving cell division, signaling, differentiation, and metabolism. Identification of thk1 provides an important new component of the DEK1 regulatory system that patterns cell fate in endosperm.

玉米 ( Zea mays )厚糊粉层 1 ( thk1-R ) 突变体在胚乳中形成多个糊粉层并阻止胚胎发生。先前的研究表明， thk1在控制糊粉细胞命运和其他胚乳性状的调控途径中，在有缺陷的 kernel1 ( dek1 ) 下游发挥作用。最初的thk1-R突变体含有约 2 Mb 的多基因缺失，这使得无法识别致病基因。在这里，甲磺酸乙酯诱变产生了额外的等位基因，并且根据与野生型祖细胞相比的差异表达，使用来自发育中胚乳的RNA测序来鉴定候选基因。基因编辑通过产生无法补充现有thk1突变体并产生多个糊粉纯合表型的突变等位基因来确认基因身份。 Thk1编码 NEGATIVE ON TATA-LESS1 的同源物，该蛋白充当碳分解代谢物抑制 4-NEGATIVE ON TATA-LESS 复合物的支架。该复合物在所有真核生物中高度保守且必不可少，可调节多种基因表达和细胞活动。玉米还含有一个重复的基因座，即厚糊粉层样1 ，这可能解释了thk1突变体形成活细胞的能力。转录组分析表明 THK1 调节涉及细胞分裂、信号传导、分化和代谢的活动。 thk1的鉴定为 DEK1 调控系统提供了一个重要的新组件，该系统决定胚乳中细胞的命运。