early bolting in short days: an Arabidopsis mutation that causes early flowering and partially suppresses the floral phenotype of leafy.

The time of flowering in Arabidopsis is controlled by multiple endogenous and environmental signals. Some of these signals promote the onset of flowering, whereas others repress it. We describe here the isolation and characterization of two allelic mutations that cause early flowering and define a new locus, EARLY BOLTING IN SHORT DAYS (EBS). Acceleration of flowering time in the ebs mutants is especially conspicuous under short-day photoperiods and results from a reduction of the adult vegetative phase of the plants. In addition to the early flowering phenotype, ebs mutants show a reduction in seed dormancy, plant size, and fertility. Double mutant analysis with gibberellin-deficient mutants indicates that both the early-flowering and the precocious-germination phenotypes require gibberellin biosynthesis. Analysis of the genetic interactions among ebs and several mutations causing late flowering shows that the ft mutant phenotype is epistatic over the early flowering of ebs mutants, suggesting that the precocious flowering of ebs requires the FT gene product. Finally, the ebs mutation causes an increase in the level of expression of the floral homeotic genes APETALA3 (AP3), PISTILLATA (PI), and AGAMOUS (AG) and partially rescues the mutant floral phenotype of leafy-6 (lfy-6) mutants. These results suggest that EBS participates as a negative regulator in developmental processes such as germination, flowering induction, and flower organ specification.

Identification of genes specifically expressed in cauliflower reproductive meristems. Molecular characterization of BoREM1.

Using the meristems of the cauliflower curd as a source of tissue and a series of subtractive hybridizations and amplification reactions, we have constructed a cDNA library highly enriched in cDNAs expressed in reproductive meristems. The analysis of a sample of 250 clones from this library identified 22 cDNA clones corresponding to genes specifically expressed in these cauliflower meristems. Apart from two clones that corresponded to APETALA1, and two other ones showing similarity to different aminoacyl-tRNA synthetases, the remaining clones showed no similarity to any sequence in the databases and may correspond to novel genes. One of these clones, BoREM1, was further characterized and found to correspond to a gene encoding a protein with features of regulatory proteins that follows a expression pattern very similar to the LEAFY transcripts.