SlCESTA Is a Brassinosteroid-Regulated bHLH Transcription Factor of Tomato That Promotes Chilling Tolerance and Fruit Growth When Over-Expressed.

Brassinosteroids (BRs) are required for various aspects of plant growth and development, but also participate in stress responses. The hormones convey their activity through transcriptional regulation and posttranslational modification of transcription factors and one class are basic helix-loop-helix (bHLH) proteins of the BR Enhanced Expression (BEE) subfamily, which in include BEE1-3 and CESTA (CES). CES and the BEEs promote the expression of different BR-responsive genes, including genes encoding gibberellin (GA) biosynthetic and catabolizing enzymes, as well as cold-responsive genes.

Brassinosteroid-regulated bHLH transcription factor CESTA induces the gibberellin 2-oxidase GA2ox7.

Brassinosteroids (BRs) are plant steroids that have growth-promoting capacities, which are partly enabled by an ability to induce biosynthesis of gibberellins (GAs), a second class of plant hormones. In addition, BRs can also activate GA catabolism; here we show that in Arabidopsis (Arabidopsis thaliana) the basic helix-loop-helix transcription factor CESTA (CES) and its homologues BRASSINOSTEROID-ENHANCED EXPRESSION (BEE) 1 and 3 contribute to this activity. CES and the BEEs are BR-regulated at the transcriptional and posttranslational level and participate in different physiological processes, including vegetative and reproduction development, shade avoidance, and cold stress responses.

The Class III Gibberellin 2-Oxidases AtGA2ox9 and AtGA2ox10 Contribute to Cold Stress Tolerance and Fertility.

Many developmental processes in plants are regulated by GA hormones. GA homeostasis is achieved via complex biosynthetic and catabolic pathways. GA catabolic enzymes include GA 2-oxidases that are classified into three classes.

Cucumber gibberellin 1-oxidase/desaturase initiates novel gibberellin catabolic pathways.

Bioactive gibberellins (GAs) are central regulators of plant growth and development, including seed development. GA homeostasis is achieved via complex biosynthetic and catabolic pathways, whose exact activities remain to be elucidated. Here, we isolated two cDNAs from mature or imbibed cucumber seeds with high sequence similarity to known GA 3-oxidases.

The Multifunctional Dioxygenases of Gibberellin Synthesis.

Gibberellin (GA) hormones regulate the development of plants and their responses to environmental signals. The final part of GA biosynthesis is catalyzed by multifunctional 2-oxoglutarate-dependent dioxygenases, which are encoded by multigene families. According to their enzymatic properties and physiological functions, GA-oxidases are classified as anabolic or catabolic enzymes.

Root-derived GA contributes to temperature-induced shoot growth in Arabidopsis.

Plants are able to sense a rise in temperature of several degrees, and appropriately adapt their metabolic and growth processes. To this end, plants produce various signalling molecules that act throughout the plant body. Here, we report that root-derived GA, a precursor of the bioactive gibberellins, mediates thermo-responsive shoot growth in Arabidopsis.

A Specific Gibberellin 20-Oxidase Dictates the Flowering-Runnering Decision in Diploid Strawberry.

Asexual and sexual reproduction occur jointly in many angiosperms. Stolons (elongated stems) are used for asexual reproduction in the crop species potato () and strawberry ( spp), where they produce tubers and clonal plants, respectively. In strawberry, stolon production is essential for vegetative propagation at the expense of fruit yield, but the underlying molecular mechanisms are unknown.

Ovary-derived precursor gibberellin A9 is essential for female flower development in cucumber.

Gibberellins (GAs) are hormones that control many aspects of plant development, including flowering. It is well known that stamen is the source of GAs that regulate male and bisexual flower development. However, little is known about the role of GAs in female flower development.

NO FLOWERING IN SHORT DAY (NFL) is a bHLH transcription factor that promotes flowering specifically under short-day conditions in Arabidopsis.

Flowering in plants is a dynamic and synchronized process where various cues including age, day length, temperature and endogenous hormones fine-tune the timing of flowering for reproductive success. Arabidopsis thaliana is a facultative long day (LD) plant where LD photoperiod promotes flowering. Arabidopsis still flowers under short-day (SD) conditions, albeit much later than in LD conditions.

Brassinosteroids Are Master Regulators of Gibberellin Biosynthesis in Arabidopsis.

Plant growth and development are highly regulated processes that are coordinated by hormones including the brassinosteroids (BRs), a group of steroids with structural similarity to steroid hormones of mammals. Although it is well understood how BRs are produced and how their signals are transduced, BR targets, which directly confer the hormone's growth-promoting effects, have remained largely elusive. Here, we show that BRs regulate the biosynthesis of gibberellins (GAs), another class of growth-promoting hormones, in Arabidopsis thaliana.

Touch-induced changes in Arabidopsis morphology dependent on gibberellin breakdown.

Touch can lead to a reduction in plant growth and a delay in flowering time. Touch-induced changes in plant morphology, termed thigmomorphogenesis, have been shown to depend on the phytohormone jasmonate(1). However, touch-induced phenotypes are also reminiscent of plants deficient in the phytohormone gibberellin(2).

The gibberellin biosynthetic genes AtKAO1 and AtKAO2 have overlapping roles throughout Arabidopsis development.

Ent-kaurenoic acid oxidase (KAO), a class of cytochrome P450 monooxygenases of the subfamily CYP88A, catalyzes the conversion of ent-kaurenoic acid (KA) to gibberellin (GA) GA12 , the precursor of all GAs, thereby playing an important role in determining GA concentration in plants. Past work has demonstrated the importance of KAO activity for growth in various plant species. In Arabidopsis, this enzyme is encoded by two genes designated KAO1 and KAO2.

Down regulation of StGA3ox genes in potato results in altered GA content and affect plant and tuber growth characteristics.

GA biosynthesis and catabolism has been shown to play an important role in regulating tuberization in potato. Active GAs are inactivated in the stolon tips shortly after induction to tuberization. Overexpression of a GA inactivation gene results in an earlier tuberization phenotype, while reducing expression of the same gene results in delayed tuberization.

Functional characterization of gibberellin oxidases from cucumber, Cucumis sativus L.

Cucurbits have been used widely to elucidate gibberellin (GA) biosynthesis. With the recent availability of the genome sequence for the economically important cucurbit Cucumis sativus, sequence data became available for all genes potentially involved in GA biosynthesis for this species. Sixteen cDNAs were cloned from root and shoot of 3-d to 7-d old seedlings and from mature seeds of C.

Genetic variation in plant CYP51s confers resistance against voriconazole, a novel inhibitor of brassinosteroid-dependent sterol biosynthesis.

Brassinosteroids (BRs) are plant steroid hormones with structural similarity to mammalian sex steroids and ecdysteroids from insects. The BRs are synthesized from sterols and are essential regulators of cell division, cell elongation and cell differentiation. In this work we show that voriconazole, an antifungal therapeutic drug used in human and veterinary medicine, severely impairs plant growth by inhibiting sterol-14α-demethylation and thereby interfering with BR production.

High levels of jasmonic acid antagonize the biosynthesis of gibberellins and inhibit the growth of Nicotiana attenuata stems.

Hormones play pivotal roles in regulating plant development, growth, and stress responses, and cross-talk among different hormones fine-tunes various aspects of plant physiology. Jasmonic acid (JA) is important for plant defense against herbivores and necrotic fungi and also regulates flower development; in addition, Arabidopsis mutants over-producing JA usually have stunted stems and wound-induced jasmonates suppress Arabidopsis growth, suggesting that JA is also involved in stem elongation. Gibberellins (GAs) promote stem and leaf growth and modulate seed germination, flowering time, and the development of flowers, fruits, and seeds.

Stamen-derived bioactive gibberellin is essential for male flower development of Cucurbita maxima L.

Gibberellin (GA) signalling during pumpkin male flower development is highly regulated, including biosynthetic, perception, and transduction pathways. GA 20-oxidases, 3-oxidases, and 2-oxidases catalyse the final part of GA synthesis. Additionally, 7-oxidase initiates this part of the pathway in some cucurbits including Cucurbita maxima L.

Release of hormones from conjugates: chloroplast expression of β-glucosidase results in elevated phytohormone levels associated with significant increase in biomass and protection from aphids or whiteflies conferred by sucrose esters.

Transplastomic tobacco (Nicotiana tabacum) plants expressing β-glucosidase (Bgl-1) show modified development. They flower 1 month earlier with an increase in biomass (1.9-fold), height (1.

Expression of the Arabidopsis mutant ABI1 gene alters abscisic acid sensitivity, stomatal development, and growth morphology in gray poplars.

The consequences of altered abscisic acid (ABA) sensitivity in gray poplar (Populus x canescens [Ait.] Sm.) development were examined by ectopic expression of the Arabidopsis (Arabidopsis thaliana) mutant abi1 (for abscisic acid insensitive1) gene.

Geranyl diphosphate synthase is required for biosynthesis of gibberellins.

Geranyl diphosphate synthase (GPS) is generally considered to be responsible for the biosynthesis of monoterpene precursors only. However, reduction of LeGPS expression in tomato (Lycopersicon esculentum) by virus-induced gene silencing resulted in severely dwarfed plants. Further analysis of these dwarfed plants revealed a decreased gibberellin content, whereas carotenoid and chlorophyll levels were unaltered.

Stable expression of AtGA2ox1 in a low-input turfgrass (Paspalum notatum Flugge) reduces bioactive gibberellin levels and improves turf quality under field conditions.

Bahiagrass (Paspalum notatum Flugge) is a prime candidate for molecular improvement of turf quality. Its persistence and low input characteristics made it the dominant utility turfgrass along highways in the south-eastern USA. However, the comparatively poor turf quality due to reduced turf density and prolific production of unsightly inflorescences currently limits the widespread use of bahiagrass as residential turf.

StGA2ox1 is induced prior to stolon swelling and controls GA levels during potato tuber development.

The formation and growth of a potato (Solanum tuberosum) tuber is a complex process regulated by different environmental signals and plant hormones. In particular, the action of gibberellins (GAs) has been implicated in different aspects of potato tuber formation. Here we report on the isolation and functional analysis of a potato GA 2-oxidase gene (StGA2ox1) and its role in tuber formation.

Ectopic expression of pumpkin gibberellin oxidases alters gibberellin biosynthesis and development of transgenic Arabidopsis plants.

Immature pumpkin (Cucurbita maxima) seeds contain gibberellin (GA) oxidases with unique catalytic properties resulting in GAs of unknown function for plant growth and development. Overexpression of pumpkin GA 7-oxidase (CmGA7ox) in Arabidopsis (Arabidopsis thaliana) resulted in seedlings with elongated roots, taller plants that flower earlier with only a little increase in bioactive GA4 levels compared to control plants. In the same way, overexpression of the pumpkin GA 3-oxidase1 (CmGA3ox1) resulted in a GA overdose phenotype with increased levels of endogenous GA4.

Gibberellin biosynthesis in developing pumpkin seedlings.

A gibberellin (GA) biosynthetic pathway was discovered operating in root tips of 7-d-old pumpkin (Cucurbita maxima) seedlings. Stepwise analysis of GA metabolism in cell-free systems revealed the conversion of GA(12)-aldehyde to bioactive GA(4) and inactive GA(34). Highest levels of endogenous GA(4) and GA(34) were found in hypocotyls and root tips of 3-d-old seedlings.