Mutational analysis of morphogenesis of the maize embryo

Abstract

SummaryMorphogenesis of the maize embryo is controlled by many genes. A group of 51 embryo-specific (emb) mutations representing at least 45 independent mutation events and many different gene loci have been isolated from active Robertson's Mutator stocks. The authors have reported previously that the embryo phenotype of 27 of these mutations, characterized by examining mature embryos in fresh dissection. The maximal development capacity of the 24 ernb mutations are reported here which have not been reported previously. All result in retarded embryos that are morphologically abnormal. Three of the mutants are blocked during the first phase of morphogenesis, the period in which the basal-apical asymmetry is established and the embryo is regionalized into suspensor and embryo proper. Nineteen mutants are blocked during the second phase, the period in which radial asymmetry appears, the embryonic axis is established at a different angle than the original basal-apical axis of the zygote and the vegetative organ primordia of the adult plant make their first appearance. Two mutants are blocked or altered during the third phase, the period in which vegetative structures are elaborated.Some of the mutants affected in the first phase of morphogenesis may have defective mechanisms for establishing basal-apical asymmetry, including possibly the asymmetric distribution of morphogenic determinants. Similarly, some of the mutants affected in the second phase may be altered in the mechanisms establishing radial asymmetry and the origin of the meristems. Mutations of the first type may act as early as the first cell division when the zygote undergoes a transverse division, while mutations of the second type are likely to act during the proembtyo and transition stages. Both types include mutations affecting embryo pattern formation. Mutations affecting the third phase of morphogenesis may identify genes

A cotyledon regulatory region is responsible for the different spatial expression patterns of Arabidopsis 2S albumin genes

“…To identify genes controlling embryo morphogenesis, mutants affecting pattern formation have been isolated and characterized (Mayer et al, 1991 ;Sheridan and Clark, 1993). An alternative approach is the analysis of cis and trans-acting factors affecting tissue-specific expression of structural genes .…”

Genetic and physiological characterization of the OsCem mutant in rice: formation of connected embryos with multiple plumules or multiple radicles

“…This stable pattern indicates that functional regionalizations in the rice embryo are regulated by specific gene(s) (Itoh et al, 2005). Although many different mutants in maize (Clark and Sheridan, 1991;Sheridan and Clark, 1993;Heckel et al, 2000) and rice (Nagato et al, 1989;Kitano et al, 1993;Hong et al, 1996;Satoh et al, 1999;Kinae et al, 2005) with abnormal embryonic development profiles have been characterized, rice mutants that produce multiple plumules and/or radicles, and even form a connected twin in the same embryo, have not previously been reported.…”

Comparative Expression and Cellular Localization of Myo-inositol Phosphate Synthase (MIPS) in the Wild Type and in an EMS Mutant During Common Bean (Phaseolus vulgaris L.) Seed Development

“…Various mutagenesis and screening approaches such as EMS, T-DNA insertion, genetic reverse, and genetic sense have been used to study the genes involved and required for embryo formation and development in A. thaliana, Z. mays, G. max, and O. sativa (Sheridan and Clark 1993;Hong et al 1995). In this optic, we have used plants deficient in seed development from the EMS-mutagenized seeds of common bean (Silué et al 2008).…”