RALFL34 regulates formative cell divisions in Arabidopsis pericycle during lateral root initiation.

In plants, many signalling molecules, such as phytohormones, miRNAs, transcription factors, and small signalling peptides, drive growth and development. However, very few small signalling peptides have been shown to be necessary for lateral root development. Here, we describe the role of the peptide RALFL34 during early events in lateral root development, and demonstrate its specific importance in orchestrating formative cell divisions in the pericycle.

PP2A-3 interacts with ACR4 and regulates formative cell division in the Arabidopsis root.

In plants, the generation of new cell types and tissues depends on coordinated and oriented formative cell divisions. The plasma membrane-localized receptor kinase ARABIDOPSIS CRINKLY 4 (ACR4) is part of a mechanism controlling formative cell divisions in the Arabidopsis root. Despite its important role in plant development, very little is known about the molecular mechanism with which ACR4 is affiliated and its network of interactions.

New perspective in ethylene signaling.

Key steps in understanding ethylene signaling have come from studying Arabidopsis mutants. The mechanisms of receptor signal output are still poorly understood and the discovery of new components has increased the apparent complexity. Not all receptors are equivalent and some appear to have unique functions.

Recent advances in ethylene research.

Ethylene regulates many aspects of the plant life cycle, including seed germination, root initiation, flower development, fruit ripening, senescence, and responses to biotic and abiotic stresses. It thus plays a key role in responses to the environment that have a direct bearing on a plant's fitness for adaptation and reproduction. In recent years, there have been major advances in our understanding of the molecular mechanisms regulating ethylene synthesis and action.

AtTRP1 encodes a novel TPR protein that interacts with the ethylene receptor ERS1 and modulates development in Arabidopsis.

Arabidopsis AtTRP1 is an orthologue of SlTPR1, a tomato tetratricopeptide repeat protein that interacts with the tomato ethylene receptors LeETR1 and NR in yeast 2-hybrid assays and in vitro, and modulates plant development. AtTRP1 is encoded by a single copy gene in the Arabidopsis genome, and is related to TCC1, a human protein that competes with Raf-1 for Ras binding, and distantly related to the immunophilin-like FK-binding proteins TWD1 and PAS1. The former is involved in auxin transport and the latter is translocated to the nucleus in response to auxin.

SlTPR1, a tomato tetratricopeptide repeat protein, interacts with the ethylene receptors NR and LeETR1, modulating ethylene and auxin responses and development.

The gaseous hormone ethylene is perceived by a family of ethylene receptors which interact with the Raf-like kinase CTR1. SlTPR1 encodes a novel TPR (tetratricopeptide repeat) protein from tomato that interacts with the ethylene receptors NR and LeETR1 in yeast two-hybrid and in vitro protein interaction assays. SlTPR1 protein with a GFP fluorescent tag was localized in the plasmalemma and nuclear membrane in Arabidopsis, and SlTPR1-CFP and NR-YFP fusion proteins were co-localized in the plasmalemma and nuclear membrane following co-bombardment of onion cells.

Improved plant transformation vectors for fluorescent protein tagging.

Fluorescent protein labelling technologies enable dynamic protein actions to be imaged in living cells and can also be used in conjunction with other methods such as Forster resonance energy transfer and biomolecular fluorescence complementation. In this report, we describe the generation of a series of 23 novel GATEWAY-compatible vectors based on pGreenII and pDH51 backbones with the latest fluorescent protein tags (Cerulean, EGFP and Venus) and the choice of three in planta selection markers. These vectors can be obtained from the Nottingham Arabidopsis Stock Centre (N9819-N9846) and should be a powerful tool box for transgenic research in plants.

A tomato HD-Zip homeobox protein, LeHB-1, plays an important role in floral organogenesis and ripening.

Ethylene is required for climacteric fruit ripening. Inhibition of ethylene biosynthesis genes, 1-aminocyclopropane-1-carboxylate (ACC) synthase and ACC oxidase, prevents or delays ripening, but it is not known how these genes are modulated during normal development. LeHB-1, a previously uncharacterized tomato homeobox protein, was shown by gel retardation assay to interact with the promoter of LeACO1, an ACC oxidase gene expressed during ripening.

Tomato ethylene receptor-CTR interactions: visualization of NEVER-RIPE interactions with multiple CTRs at the endoplasmic reticulum.

In the model plant Arabidopsis, members of a family of two-component system His kinase-like ethylene receptors have direct protein-protein interactions with a single downstream Ser/Thr kinase CTR1. These components of the ethylene signalling network found in Arabidopsis are conserved in the climacteric fruit tomato, but both the ethylene receptors and CTR1-like proteins (LeCTRs) in tomato are encoded by multigene families. Here, using a yeast two-hybrid interaction assay, it is shown that the tomato receptors LeETR1, LeETR2, and NEVER-RIPE (NR) can interact with multiple LeCTRs.

LeCTR2, a CTR1-like protein kinase from tomato, plays a role in ethylene signalling, development and defence.

Arabidopsis AtCTR1 is a Raf-like protein kinase that interacts with ETR1 and ERS and negatively regulates ethylene responses. In tomato, several CTR1-like proteins could perform this role. We have characterized LeCTR2, which has similarity to AtCTR1 and also to EDR1, a CTR1-like Arabidopsis protein involved in defence and stress responses.

Identification of a specific isoform of tomato lipoxygenase (TomloxC) involved in the generation of fatty acid-derived flavor compounds.

There are at least five lipoxygenases (TomloxA, TomloxB, TomloxC, TomloxD, and TomloxE) present in tomato (Lycopersicon esculentum Mill.) fruit, but their role in generation of fruit flavor volatiles has been unclear. To assess the physiological role of TomloxC in the generation of volatile C6 aldehyde and alcohol flavor compounds, we produced transgenic tomato plants with greatly reduced TomloxC using sense and antisense constructs under control of the cauliflower mosaic virus 35S promoter.