A mutant of Arabidopsis which is defective in seed development and storage protein accumulation is a new abi3 allele

LEA proteins are late embryogenesis abundant in the seeds of many higher plants and are probably universal in occurrence in plant seeds. LEA mRNAs and proteins can be induced to appear at other stages in the plant's life by desiccation stress and/or treatment with the plant hormone abscisic acid (ABA). A role in protecting plant structures during water loss is likely for these proteins, with ABA functioning in the stress transduction process. Presented here are conserved tracts of amino acid sequence among LEA proteins from several species that may represent domains functionally important in desiccation protection. Curiously, an 11 amino acid sequence motif is found tandemly repeated in a group of LEA proteins of vastly different sizes. Analysis of this motif suggests that it exists as an amphiphilic α helix which may serve as the basis for higher order structure.

In Arabidopsis thaliana 37 independent irradiation or EMS induced mutants were isolated which have an absolute or almost absolute gibberellin (GA) requirement for germination and successive elongation growth. These are called 'non-germinating GA-dwarfs', since without further addition of GA they develop into typical GA-dwarfs, being dark green, stunted and sterile. However, with repeated GA-treatment they develop into fertile plants with a completely wild type phenotype, or nearly so. In addition, 19 independently induced 'germinating GA-dwarfs' were obtained, i.e. mutants which do germinate without GA but develop into typical GA-dwarfs. With repeated GA-treatment these too grow to become completely wild type phenotypes, or nearly so. 'Germinating dwarfs' have been found by previous authors in a number of other plant species. The 'non-germinating dwarfs' form a new class of mutants. The system of non-germinating mutants offers a resolving power unique in higher plants, so that self-detecting rare events like induced revertants or intragenic recombinants can be efficiently screened for.The 56 GA-sensitive mutants represent mutations at 5 loci, located on three of five Arabidopsis chromosomes. At three of the five loci both mutant classes were represented in similar frequency ratio's, whilst at the other two loci only germinating dwarfs were found.

The Viviparous-1 (Vp1) gene of maize is specifically required for expression of the maturation program in seed development. We show that Vp1 encodes a 73,335 dalton protein with no detectable homology to known proteins. An acidic transcriptional activation sequence was identified by fusion to the GAL4 DNA-binding domain. Expression of VP1 in maize protoplasts resulted in strong activation (greater than 130-fold) of a reporter gene fused to the promoter of a presumptive target gene. The acidic domain in VP1 was essential for transactivation and could be functionally replaced by the activator sequence of the herpes simplex virus VP16 protein. Our results indicate that VP1 is a novel transcription factor possibly involved in potentiation of a seed-specific hormone response.