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José R Dinneny

Publications and source records attributed to José R Dinneny.

8 recordsLinked to original sources
PubMed2006

NUBBIN and JAGGED define stamen and carpel shape in Arabidopsis.

Differential growth of tissues during lateral organ development is essential for producing variation in shape and size. Previous studies have identified JAGGED (JAG), a gene that encodes a putative C2H2 zinc-finger transcription factor, as a key regulator of shape that promotes growth in lateral organs. Although JAG expression is detected in all floral organs, loss-of-function jag alleles have their strongest effects on sepal and petal development, suggesting that JAG may act redundantly with other factors in stamens and carpels. Here, we show that NUBBIN (NUB), a gene closely related to JAG, is responsible for this redundancy. Unlike JAG, NUB is exclusively expressed in leaves, stamens and carpels, and briefly in petal primordia. Furthermore, whereas JAG expression extends into all cell layers of lateral organs, NUB is restricted to the interior adaxial side. Our analysis focuses on stamen and gynoecium development, where we find that NUB acts redundantly with JAG to promote the growth of the pollen-bearing microsporangia of the anthers and the carpel walls of the gynoecium, which enclose the ovules. JAG and NUB also act redundantly to promote the differentiation of adaxial cell types in the carpel walls, and in the establishment of the correct number of cell layers. The important role these two factors play in regulating organ growth is further demonstrated by gain-of-function experiments showing that ectopic NUB expression is sufficient to drive the proliferation of tissues and the amplification of cell-layer number.

Alleles↗
PubMed2005

A genetic framework for fruit patterning in Arabidopsis thaliana.

In the model plant Arabidopsis thaliana, the establishment of organ polarity leads to the expression of FILAMENTOUS FLOWER (FIL) and YABBY3 (YAB3) on one side of an organ. One important question that has remained unanswered is how does this positional information lead to the correct spatial activation of genes controlling tissue identity? We provide the first functional link between polarity establishment and the regulation of tissue identity by showing that FIL and YAB3 control the non-overlapping expression patterns of FRUITFULL (FUL) and SHATTERPROOF (SHP), genes necessary to form stripes of valve margin tissue that allow the fruit to shatter along two defined borders and disperse the seeds. FIL and YAB3 activate FUL and SHP redundantly with JAGGED (JAG), a gene that also promotes growth in organs, indicating that several pathways converge to regulate these genes. These activities are negatively regulated by REPLUMLESS (RPL), which divides FIL/JAG activity, creating two distinct stripes of valve margin.

Arabidopsis↗
PubMed2005

Drawing lines and borders: how the dehiscent fruit of Arabidopsis is patterned.

The advent of fruits marked a key innovation in the evolution of flowering plants and helped generate a diverse array of mechanisms for seed dispersal. In the model plant, Arabidopsis thaliana, seed dispersal occurs through a process known as "pod-shatter" in which the fruit structure falls to pieces upon light mechanical pressures. This dispersal mechanism is dependent on the careful patterning of tissues in the fruit, which perform diverse functions that enable the fruit to open at maturation. Using the genetic power of Arabidopsis, many of the molecular components that help specify these tissues have been identified. Studies of the interactions among these genes have revealed a regulatory network that limits processes such as cell-cell separation and lignification to discreet regions of the fruit. Knowledge of these processes in a model fruit creates a foundation on which to build an understanding of the evolution of fruit form in other species and provides tools to engineer shatter-resistant seed pods to prevent crop loss in plants of agronomic importance such as canola.

Arabidopsis↗
PubMed2004

Floral development: an ABC gene chips in downstream.

In flower development, specification of stamens and carpels requires the AGAMOUS gene. A recent study has now shown that AGAMOUS also plays more specific roles in the regional activation of sporocyte formation.

Arabidopsis Proteins↗
PubMed2004

Vascular patterning: xylem or phloem?

Xylem and phloem are the major conduits for the transport of water and solutes through the plant. Recent work has helped to elucidate the mechanisms that determine the identity and arrangement of these two tissues.

Arabidopsis↗
PubMed2004

The role of JAGGED in shaping lateral organs.

Position-dependent regulation of growth is important for shaping organs in multicellular organisms. We have characterized the role of JAGGED, a gene that encodes a protein with a single C(2)H(2) zinc-finger domain, in controlling the morphogenesis of lateral organs in Arabidopsis thaliana. Loss of JAGGED function causes organs to have serrated margins. In leaves, the blade region is most severely affected. In sepals, petals and stamens, the strongest defects are seen in the distal regions. By monitoring cell-cycle activity in developing petals with the expression of HISTONE 4, we show that JAGGED suppresses the premature differentiation of tissues, which is necessary for the formation of the distal region. The localization of defects overlaps with the expression domain of JAGGED, which is restricted to the growing regions of lateral organs. JAGGED expression is notably absent from the cryptic bract, the remnant of a leaf-like organ that subtends the flower in many species but does not normally develop in wild-type Arabidopsis. If misexpressed, JAGGED can induce the formation of bracts, suggesting that the exclusion of JAGGED from the cryptic bract is a cause of bractless flowers in Arabidopsis.

Amino Acid Sequence↗
PubMed2003

Modes of intercellular transcription factor movement in the Arabidopsis apex.

A recent and intriguing discovery in plant biology has been that some transcription factors can move between cells. In Arabidopsis thaliana, the floral identity protein LEAFY has strong non-autonomous effects when expressed in the epidermis, mediated by its movement into underlying tissue layers. By contrast, a structurally unrelated floral identity protein, APETALA1, has only limited non-autonomous effects. Using GFP fusions to monitor protein movement in the shoot apical meristem and in floral primordia of Arabidopsis, we found a strong correlation between cytoplasmic localization of proteins and their ability to move to adjacent cells. The graded distribution of several GFP fusions with their highest levels in the cells where they are produced is compatible with the notion that this movement is driven by diffusion. We also present evidence that protein movement is more restricted laterally within layers than it is from L1 into underlying layers of the Arabidopsis apex. Based on these observations, we propose that intercellular movement of transcription factors can occur in a non-targeted fashion as a result of simple diffusion. This hypothesis raises the possibility that diffusion is the default state for many macromolecules in the Arabidopsis apex, unless they are specifically retained.

Arabidopsis↗