ENDOSPERM DEFECTIVE1 Is a Novel Microtubule-Associated Protein Essential for Seed Development inArabidopsis 

Abstract

Early endosperm development involves a series of rapid nuclear divisions in the absence of cytokinesis; thus, many endosperm mutants reveal genes whose functions are essential for mitosis. This work finds that the endosperm of Arabidopsis thaliana endosperm-defective1 (ede1) mutants never cellularizes, contains a reduced number of enlarged polyploid nuclei, and features an aberrant microtubule cytoskeleton, where the specialized radial microtubule systems and cytokinetic phragmoplasts are absent. Early embryo development is substantially normal, although occasional cytokinesis defects are observed. The EDE1 gene was cloned using a map-based approach and represents the pioneer member of a conserved plant-specific family of genes of previously unknown function. EDE1 is expressed in the endosperm and embryo of developing seeds, and its expression is tightly regulated during cell cycle progression. EDE1 protein accumulates in nuclear caps in premitotic cells, colocalizes along microtubules of the spindle and phragmoplast, and binds microtubules in vitro. We conclude that EDE1 is a novel plant-specific microtubule-associated protein essential for microtubule function during the mitotic and cytokinetic stages that generate the Arabidopsis endosperm and embryo.

Endosperm cellularization defines an important developmental transition for embryo development

“…The spätzle mutant is characterized by the absence of cellularization in the endosperm but does not show cytokinesis defects in the embryo, indicating a role for SPÄTZLE in a process specific to endosperm cellularization (Sorensen et al, 2002). Similarly, in the endosperm defective 1 (ede1) mutant, the endosperm fails to cellularize but the effects on embryo patterning are less severe, implicating a main function for EDE1 in endosperm cellularization (Pignocchi et al, 2009). However, in both mutants, embryo development is delayed after the heart stage and seed shrinkage or collapse occurs, suggesting that endosperm cellularization is crucial for normal embryo and seed development (Sorensen et al, 2002;Pignocchi et al, 2009).…”

“…Similarly, in the endosperm defective 1 (ede1) mutant, the endosperm fails to cellularize but the effects on embryo patterning are less severe, implicating a main function for EDE1 in endosperm cellularization (Pignocchi et al, 2009). However, in both mutants, embryo development is delayed after the heart stage and seed shrinkage or collapse occurs, suggesting that endosperm cellularization is crucial for normal embryo and seed development (Sorensen et al, 2002;Pignocchi et al, 2009). Interploidy crosses furthermore support an important role for endosperm cellularization in embryo development.…”

Female gametophytic cell specification and seed development require the function of the putativeArabidopsisINCENP orthologWYRD

“…Maternal effects play an important role in embryonic development in most animal species (for reviews, see Glover, 2005;Li et al, 2010;Lindeman and Pelegri, 2010) but have only recently been investigated in higher plants (for reviews, see Grossniklaus, 2005;Grossniklaus and Schneitz, 1998;Rodrigues et al, 2010). Like prl, about half of the gametophytic mutants in Arabidopsis display gametophytic maternal effects early in seed development (Moore et al, 2002;Pagnussat et al, 2005), including the well-studied FERTILIZATION-INDEPENDENT SEED (FIS) class genes (Chaudhury et al, 1997;Guitton et al, 2004;Köhler et al, 2003;Luo et al, 1999;Ohad et al, 1996;Ohad et al, 1999) and several cell cycle genes (Andreuzza et al, 2010;Pignocchi et al, 2009). How cell cycle regulators contribute to cellular differentiation is unclear because it is difficult to separate effects on proliferation and differentiation; but some, such as RBR, affect differentiation independently of their role in cell cycle regulation in both animals and plants (Inze and De Veylder, 2006;Johnston et al, 2010;Korenjak and Brehm, 2006).…”

Identification of cytoskeleton-associated genes expressed during Arabidopsis syncytial endosperm development

“…[23][24][25] Like ATK1, ATK4-like and ATK5, ATK4 clusters with the kinesin-14s, characterized by their C-terminal the specialized radial microtubule systems and cytokinetic phragmoplasts are absent. 15 This study also indicates that the MAPS, MAP65-1 and AtEB1c, may also play important roles that are specific to early endosperm development. Studies concerning these genes have revealed that MAP65s form 25 nm cross bridges between microtubules.…”