Molecular mechanisms of mutualistic and antagonistic interactions in a plant-pollinator association.

Many insects metamorphose from antagonistic larvae into mutualistic adult pollinators, with reciprocal adaptation leading to specialized insect-plant associations. It remains unknown how such interactions are established at molecular level. Here we assemble high-quality genomes of a fig species, Ficus pumila var.

Primula vulgaris (primrose) genome assembly, annotation and gene expression, with comparative genomics on the heterostyly supergene.

Primula vulgaris (primrose) exhibits heterostyly: plants produce self-incompatible pin- or thrum-form flowers, with anthers and stigma at reciprocal heights. Darwin concluded that this arrangement promotes insect-mediated cross-pollination; later studies revealed control by a cluster of genes, or supergene, known as the S (Style length) locus. The P.

-mediated transformation systems of .

Background: Genetic transformation is a valuable tool and an important procedure in plant functional genomics contributing to gene discovery, allowing powerful insights into gene function and genetically controlled characteristics. species provide one of the best-known examples of heteromorphic flower development, a breeding system which has attracted considerable attention, including that of Charles Darwin. Molecular approaches, including plant transformation give the best opportunity to define and understand the role of genes involved in floral heteromorphy in the common primrose, , along with other species.

Genetic architecture and evolution of the S locus supergene in Primula vulgaris.

Darwin's studies on heterostyly in Primula described two floral morphs, pin and thrum, with reciprocal anther and stigma heights that promote insect-mediated cross-pollination. This key innovation evolved independently in several angiosperm families. Subsequent studies on heterostyly in Primula contributed to the foundation of modern genetic theory and the neo-Darwinian synthesis.

On the origins of observations of heterostyly in Primula.

In 1862, Charles Darwin published his landmark study on the different forms of flower in Primula; he coined the term distyly and subsequently expanded his studies to other species, including those with tristyly. Darwin is widely recognized as the first to study pin and thrum flowers in Primula, and to provide an explanation for the functional significance of the two floral morphs. Our laboratory is pursuing the genes that underpin floral heteromorphy in Primula, work influenced by Darwin's observations.

Molecular characterisation of four double-flowered mutants of Silene dioica representing four centuries of variation.

Records of double-flowered Silene dioica date from the late sixteenth century and four named varieties are grown today, as previously, for their horticultural interest. Although double-flowered mutants have been characterized in several plants, their study in dioecious species is of particular interest due to influences of the homeotic mutation on the different floral whorl configurations in males and females. We have analysed four double-flowered varieties of Silene dioica: Flore Pleno and Rosea Plena date back to the seventeenth and nineteenth centuries, Thelma Kay and Firefly were recognized in the latter part of the twentieth and early twenty-first centuries.

Integration of genetic and physical maps of the Primula vulgaris S locus and localization by chromosome in situ hybridization.

Heteromorphic flower development in Primula is controlled by the S locus. The S locus genes, which control anther position, pistil length and pollen size in pin and thrum flowers, have not yet been characterized. We have integrated S-linked genes, marker sequences and mutant phenotypes to create a map of the P.

Oakleaf: an S locus-linked mutation of Primula vulgaris that affects leaf and flower development.

In Primula vulgaris outcrossing is promoted through reciprocal herkogamy with insect-mediated cross-pollination between pin and thrum form flowers. Development of heteromorphic flowers is coordinated by genes at the S locus. To underpin construction of a genetic map facilitating isolation of these S locus genes, we have characterised Oakleaf, a novel S locus-linked mutant phenotype.

Floral heteromorphy in Primula vulgaris: progress towards isolation and characterization of the S locus.

Background: The common primrose, Primula vulgaris, along with many other species of the Primulaceae, exhibits floral heteromorphy in which different individuals develop one of two possible forms of flower, known as pin and thrum. Both flower types are hermaphrodite and exhibit reciprocal positions of male and female reproductive structures, which together with a sporophytic incompatibility system, prevent self-pollination and promote out-crossing. The development of the two different forms of flower is controlled by a co-adapted linkage group of genes known as the S locus.

Hose in Hose, an S locus-linked mutant of Primula vulgaris, is caused by an unstable mutation at the Globosa locus.

Hose in Hose mutants of primrose and cowslip have been cultivated since the early 17th century and show dominant homeotic conversion of sepals to petals. The phenotype shows variable penetrance and expressivity and is linked to the S locus, which controls floral heteromorphy in Primula species. Here we demonstrate that the homeotic conversion of sepals to petals in Hose in Hose is associated with up-regulation of both Primula B-function MADS box genes PvDef and PvGlo in the first floral whorl.

Wind-borne insects mediate directional pollen transfer between desert fig trees 160 kilometers apart.

The question of how far pollen can move between plants has implications for topics as diverse as habitat fragmentation, conservation management, and the containment of genetically modified crops. The monoecious African fig tree Ficus sycomorus L. relies on the small, short-lived, night-flying, host-specific fig wasp Ceratosolen arabicus Mayr for pollination.

From gene expression to gene regulatory networks in Arabidopsis thaliana.

Background: The elucidation of networks from a compendium of gene expression data is one of the goals of systems biology and can be a valuable source of new hypotheses for experimental researchers. For Arabidopsis, there exist several thousand microarrays which form a valuable resource from which to learn.

Results: A novel Bayesian network-based algorithm to infer gene regulatory networks from gene expression data is introduced and applied to learn parts of the transcriptomic network in Arabidopsis thaliana from a large number (thousands) of separate microarray experiments.

The S locus-linked Primula homeotic mutant sepaloid shows characteristics of a B-function mutant but does not result from mutation in a B-function gene.

Floral homeotic and flower development mutants of Primula, including double, Hose in Hose, Jack in the Green and Split Perianth, have been cultivated since the late 1500s as ornamental plants but until recently have attracted limited scientific attention. Here we describe the characterization of a new mutant phenotype, sepaloid, that produces flowers comprising only sepals and carpels. The sepaloid mutation is recessive, and is linked to the S locus that controls floral heteromorphy.

Identification and characterization of pin and thrum alleles of two genes that co-segregate with the Primula S locus.

The study of heteromorphy in Primula over the past 140 years has established the reproductive significance of this breeding system. Plants produce either thrum or pin flowers that demonstrate reciprocal herkogamy. Thrums have short styles and produce large pollen from anthers at the mouth of the flower; pins have long styles and produce small pollen from anthers located within the corolla tube.

Conservation, convergence, and divergence of light-responsive, circadian-regulated, and tissue-specific expression patterns during evolution of the Arabidopsis GATA gene family.

In vitro analyses of plant GATA transcription factors have implicated some proteins in light-mediated and circadian-regulated gene expression, and, more recently, the analysis of mutants has uncovered further diverse roles for plant GATA factors. To facilitate function discovery for the 29 GATA genes in Arabidopsis (Arabidopsis thaliana), we have experimentally verified gene structures and determined expression patterns of all family members across adult tissues and suspension cell cultures, as well as in response to light and signals from the circadian clock. These analyses have identified two genes that are strongly developmentally light regulated, expressed predominantly in photosynthetic tissue, and with transcript abundance peaking before dawn.

Analysis of late stage flower development in Primula vulgaris reveals novel differences in cell morphology and temporal aspects of floral heteromorphy.

Heterostyly in Primula is characterized by the development of long-styled pin and short-styled thrum flowers, with anthers midway down the corolla tube in pin flowers, and at its mouth in thrum flowers. Other differences include pollen size and stigmatic papillae length. Several linked genes at the S locus control these differences.

Arabidopsis Co-expression Tool (ACT): web server tools for microarray-based gene expression analysis.

The Arabidopsis Co-expression Tool, ACT, ranks the genes across a large microarray dataset according to how closely their expression follows the expression of a query gene. A database stores pre-calculated co-expression results for approximately 21,800 genes based on data from over 300 arrays. These results can be corroborated by calculation of co-expression results for user-defined sub-sets of arrays or experiments from the NASC/GARNet array dataset.

The Arabidopsis co-expression tool (ACT): a WWW-based tool and database for microarray-based gene expression analysis.

We present a new WWW-based tool for plant gene analysis, the Arabidopsis Co-Expression Tool (ACT), based on a large Arabidopsis thaliana microarray data set obtained from the Nottingham Arabidopsis Stock Centre. The co-expression analysis tool allows users to identify genes whose expression patterns are correlated across selected experiments or the complete data set. Results are accompanied by estimates of the statistical significance of the correlation relationships, expressed as probability (P) and expectation (E) values.

Sex ratio strategies and the evolution of cue use.

Quantitative tests of sex allocation theory have often indicated that organism strategies deviate from model predictions. In pollinating fig wasps, Lipporrhopalum tentacularis, whole fig (brood) sex ratios are generally more female-biased than predicted by local mate competition (LMC) theory where females (foundresses) use density as a cue to assess potential LMC. We use microsatellite markers to investigate foundress sex ratios in L.

Molecular characterization of DNA sequences from the Primula vulgaris S-locus.

Primula species provide possibly the best known examples of heteromorphic flower development and this breeding system has attracted considerable attention, including that of Charles Darwin. However, despite considerable recent advances in molecular genetics, nothing is known about the molecular basis of floral heteromorphy. The first molecular marker for the Primula S-locus is reported here.

Analysis of members of the Silene latifolia Cys2/His2 zinc-finger transcription factor family during dioecious flower development and in a novel stamen-defective mutant ssf1.

Sex determination in dioecious Silene latifolia Poir. is governed by the inheritance of heteromorphic sex chromosomes. In male plants the Y chromosome influences two aspects of male organogenesis, the continued differentiation of stamen primordia and male fertility, and one aspect of female organogenesis, the arrest of development of the pistil.

Novel cell wall architecture of isoxaben-habituated Arabidopsis suspension-cultured cells: global transcript profiling and cellular analysis.

The herbicide isoxaben is a highly specific and potent inhibitor of cellulose synthesis in plants. Nevertheless, suspension-cultured cells can be habituated to grow in high concentrations of isoxaben, and apparently compensate for the disruption of cellulose synthesis by the modulation of other cell wall components. We have habituated Arabidopsis cells to isoxaben and characterized the cellular and genetic consequences.

Arabidopsis thaliana GATA factors: organisation, expression and DNA-binding characteristics.

Many light-responsive promoters contain GATA motifs and a number of nuclear proteins have been defined that interact with these elements. Type-IV zinc-finger proteins have been extensively characterised in animals and fungi and are referred to as GATA factors by virtue of their affinity for promoter elements containing this sequence. We previously identified cDNA sequences representing four Arabidopsis thaliana type-TV zinc-finger proteins.

Male specific genes from dioecious white campion identified by fluorescent differential display.

Fluorescent differential display (FDD) has been used to screen for cDNAs that are differentially up-regulated in male flowers of the dioecious plant Silene latifolia in which an X/Y chromosome system of sex determination operates. To adapt FDD to the cloning of large numbers of differential cDNAs, a novel method of confirming the differential expression of these has been devised. FDD gels were Southern electro-blotted and probed with mixtures of individual cDNA clones derived from different FDD product ligation reactions.