Modeling the Arabidopsis seed shape by a cardioid: efficacy of the adjustment with a scale change with factor equal to the Golden Ratio and analysis of seed shape in ethylene mutants

A new model for the description of Arabidopsis seed shape based on the comparison of the outline of its longitudinal section with a transformed cardioid is presented. The transformation consists of scaling the horizontal axis by a factor equal to the Golden Ratio. The elongated cardioid approximates the shape of the Arabidopsis seed with more accuracy than other figures. The length to width ratio in wild-type Columbia Arabidopsis dry seeds is close to the Golden Ratio and decreases over the course of imbibition. Dry seeds of etr1-1 mutants presented a reduced length to width ratio. Application of the new model based on the cardioid allows for comparison of shape between wild-type and mutant genotypes, revealing other general alterations in the seeds in ethylene signaling pathway mutants (etr1-1).

cDNA-AFLP analysis of seed germination in Arabidopsis thaliana identifies transposons and new genomic sequences

A cDNA-AFLP experiment was designed to identify and clone nucleotide sequences induced during seed germination in Arabidopsis thaliana. Sequences corresponding to known genes involved in processes important for germination, such as mitochondrial biogenesis, protein synthesis and cell cycle progression, were isolated. Other sequences correspond to Arabidopsis BAC clones in regions where genes have not been annotated. Notably, a number of the sequences cloned did not correspond to available sequences in the databases from the Arabidopsis genome, but instead present significant similarity with DNA from other organisms, for example fish species; among them, some may encode transposons. A number of the sequences isolated showed no significant similarity with any sequences in the public databases. Oligonucleotides derived from these new sequences were used to amplify genomic DNA of Arabidopsis. Expression analysis of representative sequences is presented. This work suggests that, during germination, there may be a massive transposon mobilization that may be useful in the annotation of new genome sequences and identification of regulatory mechanisms.