Cuticle chemistry drives the development of diffraction gratings on the surface of Hibiscus trionum petals.

Plants combine both chemical and structural means to appear colorful. We now have an extensive understanding of the metabolic pathways used by flowering plants to synthesize pigments, but the mechanisms remain obscure whereby cells produce microscopic structures sufficiently regular to interfere with light and create an optical effect. Here, we combine transgenic approaches in a novel model system, Hibiscus trionum, with chemical analyses of the cuticle, both in transgenic lines and in different species of Hibiscus, to investigate the formation of a semi-ordered diffraction grating on the petal surface.

Mechanical buckling can pattern the light-diffracting cuticle of Hibiscus trionum.

Many species have cuticular striations that play a range of roles, from pollinator attraction to surface wettability. In Hibiscus trionum, the striations span multiple cells at the base of the petal to form a pattern that produces a type of iridescence. It is postulated, using theoretical models, that the pattern of striations could result from mechanical instabilities.

Evo-Devo: Tinkering with the Stem Cell Niche to Produce Thorns.

A new study shows that the defensive thorns of Citrus plants are produced when a TCP transcription factor is expressed in axillary meristems and binds to the promoter of WUSCHEL, repressing the maintenance of cell proliferation.

TTG1 proteins regulate circadian activity as well as epidermal cell fate and pigmentation.

The Arabidopsis genome contains three genes encoding proteins of the TRANSPARENT TESTA GLABRA 1 (TTG1) WD-repeat (WDR) subfamily. TTG1 is a known regulator of epidermal cell differentiation and pigment production, while LIGHT-REGULATED WD1 and LIGHT-REGULATED WD2 are known regulators of the circadian clock. Here, we discovered a new central role for TTG1 WDR proteins as regulators of the circadian system, as evidenced by the lack of detectable circadian rhythms in a triple lwd1 lwd2 ttg1 mutant.

The cellular and genetic basis of structural colour in plants.

While the pathways that produce plant pigments have been well studied for decades, the use by plants of nanoscale structures to produce colour effects has only recently begun to be studied. A variety of plants from across the plant kingdom have been shown to use different mechanism to generate structural colours in tissues as diverse as leaves, flowers and fruits. In this review we explore the cellular mechanisms by which these nanoscale structures are built and discuss the first insights that have been published into the genetic pathways underpinning these traits.

Master Regulatory Transcription Factors in Plant Development: A Blooming Perspective.

Transcription factors that trigger major developmental decisions in plants and animals are termed "master regulators". Such master regulators are classically seen as acting on the top of a regulatory hierarchy that determines a complete developmental program, and they usually encode transcription factors. Here, we introduce master regulators of flowering time and flower development as examples to show how analysis of molecular interactions and gene-regulatory networks in plants has changed our view on the molecular mechanisms by which these factors control developmental processes.

MAF2 Is Regulated by Temperature-Dependent Splicing and Represses Flowering at Low Temperatures in Parallel with FLM.

Plants enter their reproductive phase when the environmental conditions are favourable for the successful production of progeny. The transition from vegetative to reproductive phase is influenced by several environmental factors including ambient temperature. In the model plant Arabidopsis thaliana, SHORT VEGETATIVE PHASE (SVP) is critical for this pathway; svp mutants cannot modify their flowering time in response to ambient temperature.

Gene duplication and the evolution of plant MADS-box transcription factors.

Since the first MADS-box transcription factor genes were implicated in the establishment of floral organ identity in a couple of model plants, the size and scope of this gene family has begun to be appreciated in a much wider range of species. Over the course of millions of years the number of MADS-box genes in plants has increased to the point that the Arabidopsis genome contains more than 100. The understanding gained from studying the evolution, regulation and function of multiple MADS-box genes in an increasing set of species, makes this large plant transcription factor gene family an ideal subject to study the processes that lead to an increase in gene number and the selective birth, death and repurposing of its component members.

Single amino acid change alters the ability to specify male or female organ identity.

The molecular mechanisms underlying the developmental processes that shape living organisms provide a basis to understand the evolution of biological complexity. Gene duplication allows biological functions to become separated, leading to increased complexity through subfunctionalization. Recently, the relative contributions to morphological evolution of changes to the regulatory and/or coding regions of duplicated genes have been the subject of debate.

The Arabidopsis BET bromodomain factor GTE4 regulates the mitotic cell cycle.

Proteins containing bromodomains are capable of binding to acetylated histone tails and have a role in recognizing and deciphering acetylated chromatin. Plant BET proteins contain one bromodomain. Twelve BET-encoding genes have been identified in the Arabidopsis genome.

Determination of sexual organ development.

Plant sexual organ development is initiated from the floral meristem. At early stages, the activation of a set of genes that encode transcription factors determines the identity of the floral organs. These transcription factors are known as organ identity genes, and they form multimeric complexes that bind to target genes to control their expression.

The Arabidopsis BET bromodomain factor GTE4 is involved in maintenance of the mitotic cell cycle during plant development.

Bromodomain and Extra Terminal domain (BET) proteins are characterized by the presence of two types of domains, the bromodomain and the extra terminal domain. They bind to acetylated lysines present on histone tails and control gene transcription. They are also well known to play an important role in cell cycle regulation.

Target genes of the MADS transcription factor SEPALLATA3: integration of developmental and hormonal pathways in the Arabidopsis flower.

The molecular mechanisms by which floral homeotic genes act as major developmental switches to specify the identity of floral organs are still largely unknown. Floral homeotic genes encode transcription factors of the MADS-box family, which are supposed to assemble in a combinatorial fashion into organ-specific multimeric protein complexes. Major mediators of protein interactions are MADS-domain proteins of the SEPALLATA subfamily, which play a crucial role in the development of all types of floral organs.

BASIC PENTACYSTEINE1, a GA binding protein that induces conformational changes in the regulatory region of the homeotic Arabidopsis gene SEEDSTICK.

The mechanisms for the regulation of homeotic genes are poorly understood in most organisms, including plants. We identified BASIC PENTACYSTEINE1 (BPC1) as a regulator of the homeotic Arabidopsis thaliana gene SEEDSTICK (STK), which controls ovule identity, and characterized its mechanism of action. A combination of tethered particle motion analysis and electromobility shift assays revealed that BPC1 is able to induce conformational changes by cooperative binding to purine-rich elements present in the STK regulatory sequence.