Progesterone is a mammalian gonadal hormone. In the current study, we identified and quantified progesterone in a range of higher plants by using GC-MS and examined its effects on the vegetative growth of plants. The growth of Arabidopsis (Arabidopsis thaliana) seedlings was promoted by progesterone at low concentrations but suppressed at higher concentrations under both light and dark growth conditions. The growth of the gibberellin-deficient mutant lh of pea (Pisum sativum) was also promoted by progesterone. An earlier study demonstrated that progesterone binds to MEMBRANE STEROID BINDING PROTEIN 1 (MSBP1) of Arabidopsis. In this work, we cloned the homologous genes of Arabidopsis, MSBP2 and STEROID BINDING PROTEIN (SBP), as well as of rice (Oryza sativa), OsMSBP1, OsMSBP2 and OsSBP and examined their expression in plant tissues. All of these genes, except OsMSBP1, were expressed abundantly in plant tissues. The roles of progesterone in plant growth were also discussed.

Salinity is one of the most serious constraints facing agriculture today. Some mechanical, chemical and biological approaches are being pursued to cope with soil salinity. Although exogenously treated mammalian sex hormones (MSHs), progesterone, β-estradiol and androsterone, activate significant effects in various biological aspects in plants growing under normal conditions, there is no report investigating their effects on plants growing under salt stress. The present study aimed to investigate whether MSHs could alleviate the destructive effect of salt stress on wheat seedlings and thereby increase their salt tolerance. Wheat leaves were sprayed with 10(-6), 10(-8) and 10(-10) mol L(-1) concentrations of MSH on the ninth day after sowing. MSH-treated seedlings (10-day-old seedlings) were subjected to salt stress for 5 days (between days 10 and 15).At all the concentrations tested, MSH treatment provided a significant protection against to detrimental effects of salt stress in wheat seedlings. It improved dry weight, sugar, proline, protein, chlorophyll and glutathione contents in comparison to salinity alone. Similarly, superoxide dismutase, peroxidase, catalase, ascorbate peroxidase and nitrate reductase activities also were augmented by MSH treatment. On the other hand, increases in lipid peroxidation level, superoxide production and hydrogen peroxide content arising from salt treatment were reduced by MSH treatment. The highest salt tolerance was obtained at the concentrations of 10(-6) mol L(-1) for progesterone and 10(-8) mol L(-1) for β-estradiol and for androsterone.MSHs could be used effectively to protect wheat seedlings from the destructive effects of salt stress by stimulating both enzymatic and non-enzymatic antioxidant mechanism and by promoting levels of osmotic protectants such as proline and sugars resulting in osmotic adjustment, carbon storage and radical scavenging in plants.Copyright © 2011 Society of Chemical Industry.

Steroids constitute one of the most important groups of compounds of regulatory properties both in the animal and plant kingdom. In plants, steroids such as brassinosteroids or progesterone, by binding to protein receptors in cell membranes, regulate growth and initiate processes leading to increased tolerance to stress conditions. Due to their structural similarities to sterols, these steroids may also directly interact with cellular membranes. Our aim was to determine the changes of the structural parameters of lipid membranes under the influence of hydrophobic steroid compounds, i.e., 24-epibrassinolide (EBR) and its precursor-24-epicastasterone (ECS) and progesterone (PRO). Lipids were isolated from wheat seedlings with different tolerances to frost, grown at low temperatures (5 °C) for 1.5 and 3 weeks (acclimation process). Control plants were cultured continuously at 20 °C. From galactolipids and phospholipids, the main polar lipid fractions, the monolayers were formed, using a technique of Langmuir trough. EBR and ECS were introduced into monolayers, together with lipids, whereas the PRO was dissolved in the aqueous sub-phase upon which the monolayers were spread. Measurements performed at 25 °C and 10 °C showed a significant action of the tested compounds on the physicochemical properties of the monolayers. EBR and PRO increased the area per lipid molecule in monolayers, resulting in formation of more flexible surface structures while the presence of the ECS induced the opposite effect. The influence of the polarity of lipids and steroids on the interactions in the monolayer was discussed. Lipids extracted from the membranes of wheat with the most tolerance to frost were characterized by the highest fatty acid unsaturation and steroids had a relatively weak effect on the parameters of the structure of their monolayers.Copyright © 2017 Elsevier Inc. All rights reserved.

A study of the effects of different steroids on germination and tube growth of tobacco pollen (Nicotiana tabacum L. cv Petit Havana SR1) matured in vitro is presented. Application of the mammalian steroid sex hormones (testosterone, progesterone, and estradiol) resulted in a stimulation of pollen germination and tube elongation. The presence of both steroids and flavonols in the germination medium strongly enhanced the growth of tobacco male gametophytes.

In vitro toxicity of the endocrine disruptor bisphenol A (BPA) to pollen, the male haploid generation of higher plants, was studied. BPA caused significant inhibition of both tube emergence and elongation of kiwifruit pollen in a dose-dependent manner, beginning at 10 mg · l(-1); morphological changes to tubes were also detected. Despite strong inhibition of pollen tube production and growth, a large percentage of treated cells remained viable. Immunoblotting experiments indicated that levels of BiP and 14-3-3, which are proteins involved in stress response, substantially increased in BPA-treated pollen compared to controls. The increases were dose-dependent in the range 10-50 mg · l(-1) BPA, i.e. even when germination ability was completely blocked. Steroid hormones (17 β-estradiol, progesterone and testosterone) were detected in kiwifruit pollen, and their levels increased during germination in basal medium. In a BPA treatment of 30 mg · l(-1), larger increases in both estrogen and testosterone concentrations were detected, in particular, a six-fold increase of 17 β-estradiol over control concentration (30 min). The increased hormone levels were maintained for at least the 90 min incubation. Increasing concentrations of exogenous testosterone and 17 β-estradiol increasingly inhibited pollen tube emergence and elongation. Current data for BPA-exposed kiwifruit pollen suggest a toxicity mechanism that is at least in part based on a dramatic imbalance of steroid hormone production during tube organisation, emergence and elongation. It may be concluded that BPA, a widespread environmental contaminant, can cause serious adverse effects to essential pollen functions. On a broader scale, this chemical poses a potential risk to the reproductive success of higher plants.© 2010 German Botanical Society and The Royal Botanical Society of the Netherlands.

Progesterone is a mammalian hormone that has also been discovered in plants but its physiological function in plants is not explained. Experiments using inhibitors of progesterone synthesis and binding would be useful in studies on the significance of this compound in plants. Until now, trilostane and mifepristone have been used in medical sciences as progesterone biosynthesis and binding inhibitors, respectively. We tested these synthetic steroids for the first time in plants and found that they reduced the content of progesterone in wheat. The aim of further experiments was to answer whether the potential disturbances in the production/binding of progesterone, influence resistance to environmental stress (drought) and the development of wheat. Inhibitors and progesterone were applied to plants via roots in a concentration of 0.25-0.5mg/l water. Both inhibitors lowered the activity of CO2 binding enzyme (Rubisco) in wheat exposed to drought stress and trilostane additionally lowered the chlorophyll content. However, trilostane-treated plants were rescued by treatment with exogenous progesterone. The inhibitors also modulated the development of winter wheat, which indicated the significance of steroid regulators and their receptors in this process. In this study, in addition to progesterone and its inhibitors, brassinosteroid (24-epibrassinolide) and an inhibitor of biosynthesis of brassinosteroids were also applied. Mifepristone inhibited the generative development of wheat (like 24-epibrassinolide), while trilostane (like progesterone and an inhibitor of biosynthesis of brassinosteroids) stimulated the development. We propose a model of steroid-induced regulation of the development of winter wheat, where brassinosteroids act as inhibitors of generative development, while progesterone or other pregnane derivatives act as stimulators. Copyright © 2015 Elsevier Inc. All rights reserved.

Steroids are present in living organisms as one of the most essential groups of compounds. Continuous research has led to new discoveries and the revision of existing information concerning the occurrence and the role of steroids, both in animals and plants. This article will focus on reviewing the literature studying progesterone in the plant kingdom, including its discovery, its occurrence in different plant species as well as its biological activity and molecular basis of action. This review will present and discuss the current data in addition to introducing potential directions for further research on the subject of progesterone in plants.Copyright © 2011 Elsevier Inc. All rights reserved.

Hormones regulate plant growth and development in response to external environmental stimuli via complex signal transduction pathways, which in turn form complex networks of interaction. Several classes of hormones have been reported, and their activity depends on their biosynthesis, transport, conjugation, accumulation in the vacuole, and degradation. However, the activity of a given hormone is also dependent on its interaction with other hormones. Indeed, there is a complex crosstalk between hormones that regulates their biosynthesis, transport, and/or signaling functionality, although some hormones have overlapping or opposite functions. The plant root is a particularly useful system in which to study the complex role of plant hormones in the plastic control of plant development. Physiological, cellular, and molecular genetic approaches have been used to study the role of plant hormones in root meristem homeostasis. In this review, we discuss recent findings on the synthesis, signaling, transport of hormones and role during root development and examine the role of hormone crosstalk in maintaining homeostasis in the apical root meristem.Copyright © 2012 Wiley Periodicals, Inc.

Root indeterminate growth and its outstanding ability to produce new tissues continuously make this organ a highly dynamic structure able to respond promptly to external environmental stimuli. Developmental processes therefore need to be finely tuned, and hormonal cross-talk plays a pivotal role in the regulation of root growth. In contrast to what happens in animals, plant development is a post-embryonic process. A pool of stem cells, placed in a niche at the apex of the meristem, is a source of self-renewing cells that provides cells for tissue formation. During the first days post-germination, the meristem reaches its final size as a result of a balance between cell division and cell differentiation. A complex network of interactions between hormonal pathways co-ordinates such developmental inputs. In recent years, by means of molecular and computational approaches, many efforts have been made aiming to define the molecular components of these networks. In this review, we focus our attention on the molecular mechanisms at the basis of hormone cross-talk during root meristem size determination. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.