Flowering time genes branching out.

Plants are sessile by nature, and as such they have evolved to sense changes in seasonality and their surrounding environment, and adapt to these changes. One prime example of this is the regulation of flowering time in angiosperms, which is precisely timed by the coordinative action of two proteins: FLOWERING LOCUS T (FT), and TERMINAL FLOWER 1 (TFL1). Both regulators are members of the PHOSPHATIDILETHANOLAMINE BINDING PROTEIN (PEBP) family of proteins. These regulatory proteins do not interact with DNA themselves, but instead interact with transcriptional regulators, such as FLOWERING LOCUS D (FD). FT and TFL1 were initially identified as key regulators of flowering time acting through binding with FD, however PEBP family members are also involved in shaping plant architecture and development. Next to that, PEBPs can interact with TCP transcriptional regulators, such as TEOSINTE BRANCHED 1 (TB1), a well-known regulator of plant architecture and key domestication related gene in many crops. Here, we review the role of PEBP proteins in flowering time, plant architecture and development. As these are also key yield-related traits, we will highlight fascinating examples from the model plant Arabidopsis as well as important food and feed crops such as, rice, barley, wheat, tomato, and potato.

Histone H3 lysine 36 methylation affects temperature-induced alternative splicing and flowering in plants.

BACKGROUND: Global warming severely affects flowering time and reproductive success of plants. Alternative splicing of pre-messenger RNA (mRNA) is an important mechanism underlying ambient temperature-controlled responses in plants, yet its regulation is poorly understood. An increase in temperature promotes changes in plant morphology as well as the transition from the vegetative to the reproductive phase in Arabidopsis thaliana via changes in splicing of key regulatory genes. Here we investigate whether a particular histone modification affects ambient temperature-induced alternative splicing and flowering time. RESULTS: We use a genome-wide approach and perform RNA-sequencing (RNA-seq) analyses and histone H3 lysine 36 tri-methylation (H3K36me3) chromatin immunoprecipitation sequencing (ChIP-seq) in plants exposed to different ambient temperatures. Analysis and comparison of these datasets reveal that temperature-induced differentially spliced genes are enriched in H3K36me3. Moreover, we find that reduction of H3K36me3 deposition causes alteration in temperature-induced alternative splicing. We also show that plants with mutations in H3K36me3 writers, eraser, or readers have altered high ambient temperature-induced flowering. CONCLUSIONS: Our results show a key role for the histone mark H3K36me3 in splicing regulation and plant plasticity to fluctuating ambient temperature. Our findings open new perspectives for the breeding of crops that can better cope with environmental changes due to climate change.

Analysis of the petunia MADS-box transcription factor family.

Transcription factors are key regulators of plant development. One of the major groups of transcription factors is the MADS-box family, of which at least 80 members are encoded in the Arabidopsis genome. In this study, 23 members of the petunia MADS-box transcription factor family were investigated by Northern hybridisation, phylogenetic and yeast two-hybrid analyses. Many of the genes characterised appeared to have one or more close relatives that shared similar expression patterns. Comparison of the binding interactions of these proteins revealed that some show similar interaction patterns, and hence are likely to be functionally redundant. From an evolutionary point of view, their coding genes are probably derived from a recent duplication event. Furthermore, protein-protein interaction patterns, in combination with expression patterns and phylogenetic classification, appear to offer good criteria for the identification of functional homologues. Based on comparison of such data between petunia and Arabidopsis, functions can be predicted for several MADS-box transcription factors in both species.

Ovule-specific MADS-box proteins have conserved protein-protein interactions in monocot and dicot plants.

OsMADS13 is a rice MADS-box gene that is specifically expressed in developing ovules. The amino acid sequence of OsMADS13 shows 74% similarity to those of FLORAL BINDING PROTEIN 7 (FBP7) and FBP11, the products of two MADS-box genes that are necessary and sufficient to determine ovule identity in Petunia. To assess whether OsMADS13, the putative rice ortholog of FBP7 and FBP11, has an equivalent function, several analyses were performed. Ectopic expression of FBP7 and FBP11 in Petunia results in ectopic ovule formation on sepals and petals. Here we show that ectopic expression of OsMADS13 in rice and Arabidopsis does not result in the formation of such structures. Furthermore, ectopic expression of FBP7 and FBP11 in Arabidopsis also fails to induce ectopic ovule formation. To determine whether protein-protein interactions involving putative class D MADS-box proteins have been conserved, yeast two-hybrid assays were performed. These experiments resulted in the identification of three putative partners of OsMADS13, all of them encoded by AGL2-like genes. Interestingly the Petunia FBP7 protein also interacts with AGL2-like proteins. The evolutionary conservation of the MADS-box protein partners of these ovule-specific factors was confirmed by exchange experiments which showed that the protein partners of OsMADS13 interact with FBP7 and vice versa.