Thethick aleurone1Mutant Defines a Negative Regulation of Maize Aleurone Cell Fate That Functions Downstream ofdefective kernel1       

Abstract

The maize (Zea mays) aleurone layer occupies the single outermost layer of the endosperm. The defective kernel1 (dek1) gene is a central regulator required for aleurone cell fate specification. dek1 mutants have pleiotropic phenotypes including lack of aleurone cells, aborted embryos, carotenoid deficiency, and a soft, floury endosperm deficient in zeins. Here we describe the thick aleurone1 (thk1) mutant that defines a novel negative function in the regulation of aleurone differentiation. Mutants possess multiple layers of aleurone cells as well as aborted embryos. Clonal sectors of thk1 mutant tissue in otherwise normal endosperm showed localized expression of the phenotype with sharp boundaries, indicating a localized cellular function for the gene. Sectors in leaves showed expanded epidermal cell morphology but the mutant epidermis generally remained in a single cell layer. Double mutant analysis indicated that the thk1 mutant is epistatic to dek1 for several aspects of the pleiotropic dek1 phenotype. dek1 mutant endosperm that was mosaic for thk1 mutant sectors showed localized patches of multilayered aleurone. Localized sectors were surrounded by halos of carotenoid pigments and double mutant kernels had restored zein profiles. In sum, loss of thk1 function restored the ability of dek1 mutant endosperm to accumulate carotenoids and zeins and to differentiate aleurone. Therefore the thk1 mutation defines a negative regulator that functions downstream of dek1 in the signaling system that controls aleurone specification and other aspects of endosperm development. The thk1 mutation was found to be caused by a deletion of approximately 2 megabases.

Rice caryopsis development II: Dynamic changes in the endosperm

“…Recently, several transcription factors involved in aleurone differentiation have been identified in maize (Becraft et al ; Lid et al ; Shen et al ; Yi et al ). Mutation of NAKED ENDOSPERM ( NKD ), which encodes an INDETERMINATE1‐domain containing transcription factor, led to the formation of an endosperm with a multi‐cell layer aleurone (Yi et al ).…”

Endosperm: food for humankind and fodder for scientific discoveries

“…, 2003). The signaling from Dek1 is mediated by the locus defining the negative regulator Thick Aleurone 1 of unknown identity (Yi et al. , 2011).…”

Extreme‐phenotype genome‐wide association study (XP‐GWAS): a method for identifying trait‐associated variants by sequencing pools of individuals selected from a diversity panel

“…For example, NGS-based BSA methods that rely on whole-genome shotgun sequencing have been applied to species with small genomes such as Arabidopsis (Schneeberger et al, 2009) and Saccharomyces cerevisiae (Wenger et al, 2010). Because these methods are not suitable for species with large genomes, we developed Sequenom-based BSA (Liu et al, 2010) and RNA-seq based BSA (BSR-Seq) (Liu et al, 2012); these technologies have been used by us and others to map or clone several maize genes whose qualitative mutants have large effects (Yi et al, 2011;Makarevitch et al, 2012;Li et al, 2013). Similarly, sequencing-based strategies, such as next-generation mapping (Austin et al, 2011), MutMap (Abe et al, 2012) or mapping-by-sequencing (Mascher et al, 2014) have been developed to detect point mutations in bi-parental populations.…”