Abd-El-Haliem A (2012) An unbiased method for the quantitation of disease phenotypes using a custom-built macro plugin for the program ImageJ. Methods Mol Biol 835: 635-644 Adamczyk BJ, Lehti-Shiu MD, Fernandez DE (2007) The MADS domain factors AGL15 and AGL18 act redundantly as repressors of the floral transition in Arabidopsis.

Here we describe an uncharacterized gene that negatively influences Arabidopsis growth and reproductive development. DRINK ME (DKM; bZIP30) is a member of the bZIP transcription factor family, and is expressed in meristematic tissues such as the inflorescence meristem (IM), floral meristem (FM), and carpel margin meristem (CMM). Altered DKM expression affects meristematic tissues and reproductive organ development, including the gynoecium, which is the female reproductive structure and is determinant for fertility and sexual reproduction. A microarray analysis indicates that DKM overexpression affects the expression of cell cycle, cell wall, organ initiation, cell elongation, hormone homeostasis, and meristem activity genes. Furthermore, DKM can interact in yeast and in planta with proteins involved in shoot apical meristem maintenance such as WUSCHEL, KNAT1/BP, KNAT2 and JAIBA, and with proteins involved in medial tissue development in the gynoecium such as HECATE, BELL1 and NGATHA1. Taken together, our results highlight the relevance of DKM as a negative modulator of Arabidopsis growth and reproductive development.

At the beginning of the 1990s, a simple genetic model that explained flower development was presented based on Arabidopsis thaliana and Antirrhinum majus floral homeotic mutants. According to this model, which is a milestone in plant development studies, flower development can be explained by three classes of genes (A, B and C), each one controlling the identity of organs in two adjacent whorls. Intriguingly, more than 20 years later, there are still some unanswered questions, in particular regarding the universality of the class A-function genes. Class A genes are well characterised in A. thaliana, but so far no A mutants have been described in other plant species nor in Antirrhinum majus. Here, we retrace the story that led to the proposal of the ABC model focusing on the contribution of A. majus to this model. Although fewer groups are still using A. majus as a model system, this plant was a master contributor to our comprehension of the molecular networks controlling flower development.

Plant forms display a wide variety of architectures, depending on the number of lateral branches, internode elongation and phyllotaxy. These are in turn determined by the number, the position and the fate of the Axillary Meristems (AMs). Mutants that affect AM determination during the vegetative phase have been isolated in several model plants. Among these genes, the GRAS transcription factor LATERAL SUPPRESSOR (Ls) plays a pivotal role in AM determination during the vegetative phase. Hereby we characterize the phylogenetic orthologue of Ls in Antirrhinum, ERAMOSA (ERA). Our data supported ERA control of AM formation during both the vegetative and the reproductive phase in snapdragon. A phylogenetic analysis combined with an analysis of the synteny of Ls in several species strongly supported the hypothesis that ERA is a phylogenetic orthologue of Ls, although it plays a broader role. During the reproductive phase ERA promotes the establishment of the stem niche at the bract axis but, after the reproductive transition, it is antagonized by the MADS box transcription factor SQUAMOSA (SQUA). Surprisingly double mutant era squa plants display a squa phenotype developing axillary meristems, which can eventually turn into inflorescences or flowers.The aerial plant body derives from the Shoot Apical Meristem (SAM), through the iterative production of phytomers. A phytomer unit is comprised of a node, to which a leaf is anchored, the corresponding internode and an Axillary Meristem (AM) at the leaf axil 1 . AM initiation occurs at the anlagen of the apical meristem, giving rise to new buds, again formed by a set of phytomers that can remain dormant or grow out 2 . Plants produce new AMs throughout their life cycle, but the nature and properties of AMs change during the different developmental phases. This becomes evident after the floral transition, since the committed floral meristems are indeed products of AMs and are homologous to vegetative axillary buds 3 . Two theories have been proposed to explain AM formation. The 'detached meristem' theory proposes that the SAM gives rise to AMs during the production of leaf primordia In several plant species, mutants impaired in plant architecture have been described, suggesting a tight genetic control. They are grouped into three main classes: mutants affected in AM initiation, meristem outgrowth, or both 6 . An interesting mutant altered in AM initiation is the tomato lateral suppressor (ls) 7 . Ls function is quite conserved, as indicated by its orthologues in Arabidopsis thaliana (LAS) and in Oryza sativa (MONOCULM1, MOC1) 7-9 . All these mutants fail to produce vegetative AMs. Compared to wild-type plants, tomato ls plants produce fewer flowers (without petals); similarly the rice moc1 rachis forms fewer branches and spikelets 9 . Conversely, the Arabidopsis las plants do not develop lateral branches during vegetative growth, but inflorescences and flowers appear normal.The Antirrhinum majus eramosa phenotype is caused by the disruption of the Ls orthologue ERA. era pla...