Inflorescence Meristem Fate Is Dependent on Seed Development and FRUITFULL in .

After a vegetative phase, plants initiate the floral transition in response to both environmental and endogenous cues to optimize reproductive success. During this process, the vegetative shoot apical meristem (SAM), which was producing leaves and branches, becomes an inflorescence SAM and starts producing flowers. Inflorescences can be classified in two main categories, depending on the fate of the inflorescence meristem: determinate or indeterminate.

Gibberellins negatively modulate ovule number in plants.

Ovule formation is a complex developmental process in plants, with a strong impact on the production of seeds. Ovule primordia initiation is controlled by a gene network, including components of the signaling pathways of auxin, brassinosteroids and cytokinins. By contrast, gibberellins (GAs) and DELLA proteins, the negative regulators of GA signaling, have never been shown to be involved in ovule initiation.

Ovule identity mediated by pre-mRNA processing in Arabidopsis.

Ovules are fundamental for plant reproduction and crop yield as they are the precursors of seeds. Therefore, ovule specification is a critical developmental program. In Arabidopsis thaliana, ovule identity is redundantly conferred by the homeotic D-class genes SHATTERPROOF1 (SHP1), SHP2 and SEEDSTICK (STK), phylogenetically related to the MADS-domain regulatory gene AGAMOUS (AG), essential in floral organ specification.

A role for the gene regulatory module microRNA172/TARGET OF EARLY ACTIVATION TAGGED 1/FLOWERING LOCUS T (miRNA172/TOE1/FT) in the feeding sites induced by Meloidogyne javanica in Arabidopsis thaliana.

Root knot nematodes (RKNs) penetrate into the root vascular cylinder, triggering morphogenetic changes to induce galls, de novo formed 'pseudo-organs' containing several giant cells (GCs). Distinctive gene repression events observed in early gall/GCs development are thought to be mediated by post-transcriptional silencing via microRNAs (miRNAs), a process that is far from being fully characterized. Arabidopsis thaliana backgrounds with altered activities based on target 35S::MIMICRY172 (MIM172), 35S::TARGET OF EARLY ACTIVATION TAGGED 1 (TOE1)-miR172-resistant (35S::TOE1 ) and mutant (flowering locus T-10 (ft-10)) lines were used for functional analysis of nematode infective and reproductive parameters.

Control of plant cell fate transitions by transcriptional and hormonal signals.

Plant meristems carry pools of continuously active stem cells, whose activity is controlled by developmental and environmental signals. After stem cell division, daughter cells that exit the stem cell domain acquire transit amplifying cell identity before they are incorporated into organs and differentiate. In this study, we used an integrated approach to elucidate the role of () genes in regulating developmental trajectories of shoot stem cells in .

The bHLH transcription factor SPATULA enables cytokinin signaling, and both activate auxin biosynthesis and transport genes at the medial domain of the gynoecium.

Fruits and seeds are the major food source on earth. Both derive from the gynoecium and, therefore, it is crucial to understand the mechanisms that guide the development of this organ of angiosperm species. In Arabidopsis, the gynoecium is composed of two congenitally fused carpels, where two domains: medial and lateral, can be distinguished.

The class III peroxidase PRX17 is a direct target of the MADS-box transcription factor AGAMOUS-LIKE15 (AGL15) and participates in lignified tissue formation.

Several physiological functions have been attributed to class III peroxidases (PRXs) in plants, but the in planta role of most members of this family still remains undetermined. Here, we report the first functional characterization of PRX17 (At2g22420), one of the 73 members of this family in Arabidopsis thaliana. Localization of PRX17 was examined by transient expression in Nicotiana benthamiana.

3' Rapid Amplification of cDNA Ends (3' RACE) Using Samples.

Production of functional eukaryotic RNA is a very elaborate process that involves a complex interplay between transcription and various RNA processing activities, including splicing, 5' capping, and 3' cleavage and polyadenylation (Bentley, 2014). Accurate mapping of RNA ends provides a valuable tool to assess transcriptional and post-transcriptional events giving rise to different gene transcripts. The abundance of such transcripts most likely depends on exogenous and developmental cues, or mutations.

K-homology nuclear ribonucleoproteins regulate floral organ identity and determinacy in arabidopsis.

Post-transcriptional control is nowadays considered a main checking point for correct gene regulation during development, and RNA binding proteins actively participate in this process. Arabidopsis thaliana FLOWERING LOCUS WITH KH DOMAINS (FLK) and PEPPER (PEP) genes encode RNA-binding proteins that contain three K-homology (KH)-domain, the typical configuration of Poly(C)-binding ribonucleoproteins (PCBPs). We previously demonstrated that FLK and PEP interact to regulate FLOWERING LOCUS C (FLC), a central repressor of flowering time.

Plant development. Genetic control of distal stem cell fate within root and embryonic meristems.

The root meristem consists of populations of distal and proximal stem cells and an organizing center known as the quiescent center. During embryogenesis, initiation of the root meristem occurs when an asymmetric cell division of the hypophysis forms the distal stem cells and quiescent center. We have identified NO TRANSMITTING TRACT (NTT) and two closely related paralogs as being required for the initiation of the root meristem.

microRNA regulation of fruit growth.

Growth is a major factor in plant organ morphogenesis and is influenced by exogenous and endogenous signals including hormones. Although recent studies have identified regulatory pathways for the control of growth during vegetative development, there is little mechanistic understanding of how growth is controlled during the reproductive phase. Using Arabidopsis fruit morphogenesis as a platform for our studies, we show that the microRNA miR172 is critical for fruit growth, as the growth of fruit is blocked when miR172 activity is compromised.

Antagonistic gene activities determine the formation of pattern elements along the mediolateral axis of the Arabidopsis fruit.

The Arabidopsis fruit mainly consists of a mature ovary that shows three well defined territories that are pattern elements along the mediolateral axis: the replum, located at the medial plane of the flower, and the valve and the valve margin, both of lateral nature. JAG/FIL activity, which includes the combined functions of JAGGED (JAG), FILAMENTOUS FLOWER (FIL), and YABBY3 (YAB3), contributes to the formation of the two lateral pattern elements, whereas the cooperating genes BREVIPEDICELLUS (BP) and REPLUMLESS (RPL) promote replum development. A recent model to explain pattern formation along the mediolateral axis hypothesizes that JAG/FIL activity and BP/RPL function as antagonistic lateral and medial factors, respectively, which tend to repress each other.

The WOX13 homeobox gene promotes replum formation in the Arabidopsis thaliana fruit.

The Arabidopsis fruit forms a seedpod that develops from the fertilized gynoecium. It is mainly comprised of an ovary in which three distinct tissues can be differentiated: the valves, the valve margins and the replum. Separation of cells at the valve margin allows for the valves to detach from the replum and thus dispersal of the seeds.

A novel role for the floral homeotic gene APETALA2 during Arabidopsis fruit development.

The majority of the Arabidopsis fruit comprises an ovary with three primary tissue types: the valves, the replum and the valve margins. The valves, which are derived from the ovary walls, are separated along their entire length by the replum. The valve margin, which consists of a separation layer and a lignified layer, forms as a narrow stripe of cells at the valve-replum boundaries.

HALF FILLED promotes reproductive tract development and fertilization efficiency in Arabidopsis thaliana.

Successful fertilization in angiosperms requires the growth of pollen tubes through the female reproductive tract as they seek out unfertilized ovules. In Arabidopsis, the reproductive tract begins with the stigma, where pollen grains initially adhere, and extends through the transmitting tract of the style and ovary. In wild-type plants, cells within the transmitting tract produce a rich extracellular matrix and undergo programmed cell death to facilitate pollen movement.

Brassicaceae INDEHISCENT genes specify valve margin cell fate and repress replum formation.

Members of the Brassicaceae family, including Arabidopsis thaliana and oilseed rape (Brassica napus), produce dry fruits that open upon maturity along a specialised tissue called the valve margin. Proper development of the valve margin in Arabidopsis is dependent on the INDEHISCENT (IND) gene, the role of which in genetic and hormonal regulation has been thoroughly characterised. Here we perform phylogenetic comparison of IND genes in Arabidopsis and Brassica to identify conserved regulatory sequences that are responsible for specific expression at the valve margin.

A regulated auxin minimum is required for seed dispersal in Arabidopsis.

Local hormone maxima are essential for the development of multicellular structures and organs. For example, steroid hormones accumulate in specific cell types of the animal fetus to induce sexual differentiation and concentration peaks of the plant hormone auxin direct organ initiation and mediate tissue patterning. Here we provide an example of a regulated local hormone minimum required during organogenesis.

The NGATHA genes direct style development in the Arabidopsis gynoecium.

The gynoecium is the most complex floral organ, designed to protect the ovules and ensure their fertilization. Correct patterning and tissue specification in the developing gynoecium involves the concerted action of a host of genetic factors. In addition, apical-basal patterning into different domains, stigma and style, ovary and gynophore, appears to depend on the establishment and maintenance of asymmetric auxin distribution, with an auxin maximum at the apex.

Regulation of membrane trafficking and organ separation by the NEVERSHED ARF-GAP protein.

Cell separation, or abscission, is a highly specialized process in plants that facilitates remodeling of their architecture and reproductive success. Because few genes are known to be essential for organ abscission, we conducted a screen for mutations that alter floral organ shedding in Arabidopsis. Nine recessive mutations that block shedding were found to disrupt the function of an ADP-ribosylation factor-GTPase-activating protein (ARF-GAP) we have named NEVERSHED (NEV).

The formation and function of the female reproductive tract in flowering plants.

In angiosperms, sexual reproduction requires a sperm cell, contained within a pollen tube, to fertilize the egg cell. The pollen tubes are capable of growth but have a difficult journey, as egg cells are buried within the ovary of the carpel. Several tissues, known collectively as the reproductive tract, develop within the carpel to facilitate the journey of the pollen tube.

The HECATE genes regulate female reproductive tract development in Arabidopsis thaliana.

Successful fertilization in plants requires the properly coordinated development of female reproductive tissues, including stigma, style, septum and transmitting tract. We have identified three closely related genes, HECATE1 (HEC1), HECATE2 (HEC2) and HECATE3 (HEC3), the expression domains of which encompass these regions of the Arabidopsis gynoecium. The HEC genes encode putative basic helix-loop-helix (bHLH) transcription factors with overlapping functionality.

The NTT gene is required for transmitting-tract development in carpels of Arabidopsis thaliana.

Background: The majority of pollen-tube growth in Arabidopsis occurs in specialized tissue called the transmitting tract. Little is currently known about how the transmitting tract functions because of a lack of mutants affecting its development. We have identified such a mutant and we used it to investigate aspects of pollen-tube growth.

Pod shatter-resistant Brassica fruit produced by ectopic expression of the FRUITFULL gene.

Arabidopsis has proven to be extremely useful as a reference organism for studies in plant biology, and huge efforts have been employed to unravel various mechanisms of Arabidopsis growth. A major challenge now is to demonstrate that this wealth of knowledge can be used for global agricultural and environmental improvement. Brassica species are closely related to Arabidopsis and represent ideal candidates for model-to-crop approaches as they include important crop plants, such as canola.