Involvement of IDA-HAE Module in Natural Development of Tomato Flower Abscission.

The detachment of organs such as flowers, leaves, and fruits from the main body of a plant (abscission) has significant effects on agricultural practice. Both timely and precise regulation of organ abscission from a plant is crucial as it influences the agricultural yield. The tomato () has become a model system for research on organ abscission.

Varying Atmospheric CO Mediates the Cold-Induced CBF-Dependent Signaling Pathway and Freezing Tolerance in Arabidopsis.

Changes in the stomatal aperture in response to CO levels allow plants to manage water usage, optimize CO uptake and adjust to environmental stimuli. The current study reports that sub-ambient CO up-regulated the low temperature induction of the C-repeat Binding Factor (CBF)-dependent cold signaling pathway in Arabidopsis () and the opposite occurred in response to supra-ambient CO. Accordingly, cold induction of various downstream cold-responsive genes was modified by CO treatments and expression changes were either partially or fully CBF-dependent.

Ethylene and Modulate Expression of Class I Small Heat Shock Protein Genes During Tomato Fruit Ripening.

Heat shock proteins (HSPs) are ubiquitous and highly conserved in nature. Heat stress upregulates their gene expression and now it is known that they are also developmentally regulated. We have studied regulation of small HSP genes during ripening of tomato fruit.

Transcriptional Regulation of Abscission Zones.

Precise and timely regulation of organ separation from the parent plant (abscission) is consequential to improvement of crop productivity as it influences both the timing of harvest and fruit quality. Abscission is tightly associated with plant fitness as unwanted organs (petals, sepals, filaments) are shed after fertilization while seeds, fruits, and leaves are cast off as means of reproductive success or in response to abiotic/biotic stresses. Floral organ abscission in Arabidopsis has been a useful model to elucidate the molecular mechanisms that underlie the separation processes, and multiple abscission signals associated with the activation and downstream pathways have been uncovered.

Re-evaluation of the ethylene-dependent and -independent pathways in the regulation of floral and organ abscission.

Abscission is a developmental process with important implications for agricultural practices. Ethylene has long been considered as a key regulator of the abscission process. The existence of an ethylene-independent abscission pathway, controlled by the complex of INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) peptide and the HAESA (HAE) and HAESA-like2 (HSL2) kinases, has been proposed, based mainly on observations that organ abscission in ethylene-insensitive mutants was delayed but not inhibited.

The root-knot nematode Meloidogyne incognita produces a functional mimic of the Arabidopsis INFLORESCENCE DEFICIENT IN ABSCISSION signaling peptide.

INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) is a signaling peptide that regulates cell separation in Arabidopsis including floral organ abscission and lateral root emergence. IDA is highly conserved in dicotyledonous flowering plant genomes. IDA-like sequences were also found in the genomic sequences of root-knot nematodes, Meloidogyne spp.

Transient regulation of three clustered tomato class-I small heat-shock chaperone genes by ethylene is mediated by SlMADS-RIN transcription factor.

Clustered class-I small heat-shock protein (sHSP) chaperone genes, SlHSP17.6, SlHSP20.0 and SlHSP20.

Treatment of Plants with Gaseous Ethylene and Gaseous Inhibitors of Ethylene Action.

The gaseous nature of ethylene affects not only its role in plant biology but also how you treat plants with the hormone. In many ways, it simplifies the treatment problem. Other hormones have to be made up in solution and applied to some part of the plant hoping the hormone will be taken up into the plant and translocated throughout the plant at the desired concentration.

Transcriptome Analysis of Soybean Leaf Abscission Identifies Transcriptional Regulators of Organ Polarity and Cell Fate.

Abscission, organ separation, is a developmental process that is modulated by endogenous and environmental factors. To better understand the molecular events underlying the progression of abscission in soybean, an agriculturally important legume, we performed RNA sequencing (RNA-seq) of RNA isolated from the leaf abscission zones (LAZ) and petioles (Non-AZ, NAZ) after treating stem/petiole explants with ethylene for 0, 12, 24, 48, and 72 h. As expected, expression of several families of cell wall modifying enzymes and many pathogenesis-related (PR) genes specifically increased in the LAZ as abscission progressed.

De novo Transcriptome Sequencing and Development of Abscission Zone-Specific Microarray as a New Molecular Tool for Analysis of Tomato Organ Abscission.

Abscission of flower pedicels and leaf petioles of tomato (Solanum lycopersicum) can be induced by flower removal or leaf deblading, respectively, which leads to auxin depletion, resulting in increased sensitivity of the abscission zone (AZ) to ethylene. However, the molecular mechanisms that drive the acquisition of abscission competence and its modulation by auxin gradients are not yet known. We used RNA-Sequencing (RNA-Seq) to obtain a comprehensive transcriptome of tomato flower AZ (FAZ) and leaf AZ (LAZ) during abscission.

Examination of the Abscission-Associated Transcriptomes for Soybean, Tomato, and Arabidopsis Highlights the Conserved Biosynthesis of an Extensible Extracellular Matrix and Boundary Layer.

Abscission zone (AZ) development and the progression of abscission (detachment of plant organs) have been roughly separated into four stages: first, AZ differentiation; second, competence to respond to abscission signals; third, activation of abscission; and fourth, formation of a protective layer and post-abscission trans-differentiation. Stage three, activation of abscission, is when changes in the cell wall and extracellular matrix occur to support successful organ separation. Most abscission research has focused on gene expression for enzymes that disassemble the cell wall within the AZ and changes in phytohormones and other signaling events that regulate their expression.

To grow old: regulatory role of ethylene and jasmonic acid in senescence.

Senescence, the final stage in the development of an organ or whole plant, is a genetically programmed process controlled by developmental and environmental signals. Age-related signals underlie the onset of senescence in specific organs (leaf, flower, and fruit) as well as the whole plant (monocarpic senescence). Rudimentary to most senescence processes is the plant hormone ethylene, a small gaseous molecule critical to diverse processes throughout the life of the plant.

Abscission of flowers and floral organs is closely associated with alkalization of the cytosol in abscission zone cells.

In vivo changes in the cytosolic pH of abscission zone (AZ) cells were visualized using confocal microscopic detection of the fluorescent pH-sensitive and intracellularly trapped dye, 2',7'-bis-(2-carboxyethyl)-5(and-6)-carboxyfluorescein (BCECF), driven by its acetoxymethyl ester. A specific and gradual increase in the cytosolic pH of AZ cells was observed during natural abscission of flower organs in Arabidopsis thaliana and wild rocket (Diplotaxis tenuifolia), and during flower pedicel abscission induced by flower removal in tomato (Solanum lycopersicum Mill). The alkalization pattern in the first two species paralleled the acceleration or inhibition of flower organ abscission induced by ethylene or its inhibitor 1-methylcyclopropene (1-MCP), respectively.

The haustorial transcriptomes of Uromyces appendiculatus and Phakopsora pachyrhizi and their candidate effector families.

Haustoria of biotrophic rust fungi are responsible for the uptake of nutrients from their hosts and for the production of secreted proteins, known as effectors, which modulate the host immune system. The identification of the transcriptome of haustoria and an understanding of the functions of expressed genes therefore hold essential keys for the elucidation of fungus-plant interactions and the development of novel fungal control strategies. Here, we purified haustoria from infected leaves and used 454 sequencing to examine the haustorial transcriptomes of Phakopsora pachyrhizi and Uromyces appendiculatus, the causal agents of soybean rust and common bean rust, respectively.

A gene encoding a peptide with similarity to the plant IDA signaling peptide (AtIDA) is expressed most abundantly in the root-knot nematode (Meloidogyne incognita) soon after root infection.

Small peptides play important roles in intercellular signaling. Inflorescence deficient in abscission (ida) is an Arabidopsis mutant that does not abscise (shed) its flower petals. The IDA gene encodes a small, secreted peptide that putatively binds to two redundant receptor-like kinases (HAESA and HAESA-like2) that initiate a signal transduction pathway.

CTR1 phosphorylates the central regulator EIN2 to control ethylene hormone signaling from the ER membrane to the nucleus in Arabidopsis.

The gaseous phytohormone ethylene C(2)H(4) mediates numerous aspects of growth and development. Genetic analysis has identified a number of critical elements in ethylene signaling, but how these elements interact biochemically to transduce the signal from the ethylene receptor complex at the endoplasmic reticulum (ER) membrane to transcription factors in the nucleus is unknown. To close this gap in our understanding of the ethylene signaling pathway, the challenge has been to identify the target of the CONSTITUTIVE TRIPLE RESPONSE1 (CTR1) Raf-like protein kinase, as well as the molecular events surrounding ETHYLENE-INSENSITIVE2 (EIN2), an ER membrane-localized Nramp homolog that positively regulates ethylene responses.

Proteomic pleiotropy of OpgGH, an operon necessary for efficient growth of Salmonella enterica serovar typhimurium under low-osmotic conditions.

Salmonella enterica, a bacterial, food-borne pathogen of humans, can contaminate raw fruits and vegetables. Unfortunately for consumers, the bacteria can survive in water used to wash away contaminating bacteria. The ability to survive the low-osmotic conditions of the wash water is attributed to the OpgGH operon that leads to the production of osmotically regulated periplasmic glucans.

IDA-like gene expression in soybean and tomato leaf abscission and requirement for a diffusible stelar abscission signal.

Background And Aims: The stimulatory and inhibitory role of ethylene and auxin, respectively, in leaf abscission (leaf drop) is well documented. More recently, IDA (INFLORESCENCE DEFICIENT IN ABSCISSION) peptides and their putative interacting receptor-like-kinase partners, HAESA and HAESA-like2, were shown to be essential components in Arabidopsis floral organ abscission. Prior to research on IDA, it was reported that bean (Phaseolus vulgaris) leaf abscission required a diffusible signal that emanated from the vascular tissue.

Proteomic responses in Arabidopsis thaliana seedlings treated with ethylene.

Ethylene (ET) is a volatile hormone that modulates fruit ripening, plant growth, development and stress responses. Key components of the ET-signaling pathway identified by genetic dissection in Arabidopsis thaliana include five ET receptors, the negative regulator CTR1 and the positive regulator EIN2, all of which localize to the endoplasmic reticulum. Mechanisms of signaling among these proteins are still unresolved and targets of ET responses are not fully known.

Gene expression profiling and shared promoter motif for cell wall-modifying proteins expressed in soybean cyst nematode-infected roots.

We hypothesized that soybean cyst nematode (SCN; Heterodera glycines) co-opts part or all of one or more innate developmental process in soybean (Glycine max) to establish its feeding structure, syncytium, in soybean roots. The syncytium is formed within the vascular bundle by partial degradation of cell walls and membranes between adjacent parenchyma cells. A mature syncytium incorporates as many as 200 cells into one large multinucleated cell.

1-Aminocyclopropane-1-carboxylic acid (ACC) concentration and ACC synthase expression in soybean roots, root tips, and soybean cyst nematode (Heterodera glycines)-infected roots.

Colonization of plant roots by root knot and cyst nematodes requires a functional ethylene response pathway. However, ethylene plays many roles in root development and whether its role in nematode colonization is direct or indirect, for example lateral root initiation or root hair growth, is not known. The temporal requirement for ethylene and localized synthesis of ethylene during the life span of soybean cyst nematode (SCN) on soybean roots was further investigated.

Quantitative proteomic analysis of bean plants infected by a virulent and avirulent obligate rust fungus.

Plants appear to have two types of active defenses, a broad-spectrum basal system and a system controlled by R-genes providing stronger resistance to some pathogens that break the basal defense. However, it is unknown if the systems are separate entities. Therefore, we analyzed proteins from leaves of the dry bean crop plant Phaseolus vulgaris using a high-throughput liquid chromatography tandem mass spectrometry method.

GeneChip profiling of transcriptional responses to soybean cyst nematode, Heterodera glycines, colonization of soybean roots.

Soybean cyst nematode (SCN) is currently the most devastating pathogen of soybean. SCN penetrates the root and migrates toward the central vascular bundle where it establishes a complex multinucleated feeding structure that provides plant-derived nutrients to support the development and growth of the nematode. To identify host genes that play significant roles in SCN development in susceptible roots, RNA from SCN-inoculated and non-inoculated root pieces were hybridized to the Affymetrix soybean genome GeneChips.

Gene expression profiles for cell wall-modifying proteins associated with soybean cyst nematode infection, petiole abscission, root tips, flowers, apical buds, and leaves.

Changes in transcript accumulation for cell wall-modifying proteins were examined in excised soybean root pieces colonized by soybean cyst nematodes (SCN), Heterodera glycines, using RT-PCR and soybean Affymetrix GeneChips. Sequence-specific PCR primer pairs were prepared from sequence data for core sequences in the GenBank soybean database and consensus sequences derived from the assembly of soybean ESTs. In addition, to identify previously uncharacterized soybean transcripts, degenerate primers were prepared for conserved motifs in cellulases (endo-1,4-beta-glucanases, EGases) and polygalacturonases (PGs) and these were used to amplify segments of transcripts that were then extended with 3' and 5' RACE.