Versatile roles of brassinosteroid in plants in the context of its homoeostasis, signaling and crosstalks

Brassinosteroids are a class of steroidal plant hormones that play diverse roles in plant growth and developmental processes. Recently, the easy availability of biological resources, and development of new molecular tools and approaches have provided the required impetus for deeper understanding of the processes involved in brassinosteroids biosynthesis, transport, signaling and degradation pathways. From recent studies it is also evident that brassinosteroids interact with other phytohormones such as auxin, cytokinin, ethylene, gibberellin, jasmonic acid, abscisic acid, salicylic acid and polyamine in regulating wide range of physiological and developmental processes in plants. The inputs from these studies are now being linked to the versatile roles of brassinosteroids. The present review highlights the conceptual development with regard to BR homeostasis, signaling and its crosstalk with other phytohormones. This information will assist in developing predictive models to modulate various useful traits in plants and address current challenges in agriculture

Abiotic Stress Responses in Plants: Current Knowledge and Future Prospects

Exposure to abiotic stresses has become a major threatening factor that hurdles the sustainable growth in agriculture for fulfilling the growing food demand worldwide. A significant decrease in the production of major food crops including wheat, rice, and maize is predicted in the near future due to the combined effect of abiotic stresses and climate change that will hamper global food security. Thus, desperate efforts are necessary to develop abiotic stress-resilient crops with improved agronomic traits. For this, detailed knowledge of the underlying mechanisms responsible for abiotic stress adaptation in plants is must required. Plants being sessile organisms respond to different stresses through complex and diverse responses that are integrated on various whole plants, cellular, and molecular levels. The advanced genetic and molecular tools have uncovered these complex stress adaptive processes and have provided critical inputs on their regulation. The present chapter focuses on understanding the different responses of the plants involved in abiotic stress adaptation and strategies employed to date for achieving stress resistance in plants

In silico insights on diverse interacting partners and phosphorylation sites of respiratory burst oxidase homolog (Rbohs) gene families from Arabidopsis and rice

Abstract Background NADPH oxidase (Nox) is a critical enzyme involved in the generation of apoplastic superoxide (O2 −), a type of reactive oxygen species (ROS) and hence regulate a wide range of biological functions in many organisms. Plant Noxes are the homologs of the catalytic subunit from mammalian NADPH oxidases and are known as respiratory burst oxidase homologs (Rbohs). Previous studies have highlighted their versatile roles in tackling different kind of stresses and in plant growth and development. In the current study, potential interacting partners and phosphorylation sites were predicted for Rboh proteins from two model species (10 Rbohs from Arabidopsis thaliana and 9 from Oryza sativa japonica). The present work is the first step towards in silico prediction of interacting partners and phosphorylation sites for Rboh proteins from two plant species. Results In this work, an extensive range of potential partners (unique and common), leading to diverse functions were revealed from interaction networks and gene ontology classifications, where majority of AtRbohs and OsRbohs play role in stress-related activities, followed by cellular development. Further, 68 and 38 potential phosphorylation sites were identified in AtRbohs and OsRbohs, respectively. Their distribution, location and kinase specificities were also predicted and correlated with experimental data as well as verified with the other EF-hand containing proteins within both genomes. Conclusions Analysis of regulatory mechanisms including interaction with diverse partners and post-translational modifications like phosphorylation have provided insights regarding functional multiplicity of Rbohs. The bioinformatics-based workflow in the current study can be used to get insights for interacting partners and phosphorylation sites from Rbohs of other plant species

Integrating Classical with Emerging Concepts for Better Understanding of Salinity Stress Tolerance Mechanisms in Rice

Rice is an important cereal crop responsible for world's food security. The sensitivity of rice plants toward a range of abiotic stresses is a prime challenge for its overall growth and productivity. Among these, salinity is a major stress which results in a significant loss of global rice yield annually. For finding straightforward and strict future solutions in order to assure the food security to growing world population, understanding of the various mechanisms responsible for salt stress tolerance in rice is of paramount importance. In classical studies, identification of salt tolerant cultivars and the genetic markers linked to salt tolerance and breeding approaches have been given emphasis. It further affirmed on the identification of various pathways regulating the complex process of salt stress adaptation. However, only limited success has been achieved in these approaches as salt tolerance is a complex process and is governed by multiple factors. Hence, for better understanding of salt tolerance mechanisms, a comprehensive approach involving physiological, biochemical and molecular studies is much warranted. Modern experimental and genetic resources have provided a momentum in this direction and have provided molecular insights into different salt stress responsive pathways at the signaling and regulatory level. The integrative knowledge of classical and modern research of the understanding of salt stress adaptive pathways can help the researchers for designing effective strategies to fight against salt stress. Hence, the present review is focused on the understanding of the salt stress tolerance mechanisms in rice through the consolidative knowledge of classical and modern concepts. It further highlights the emerging new trends of salt stress adaptive pathways in rice

Regulation of growth and antioxidant enzyme activities by 28-homobrassinolide in seedlings of <i>Raphanus sativus</i><strong> </strong>L. under cadmium stress

172-17728-Homobrassinolide (28-HBL), a brassinosteroid is reported to play significant role in diverse physiological processes. It induces a range of cellular and adaptive responses to a range of environmental stresses. Cadmium (Cd) is a non-essential metal which alters various physiological processes and generates ROS, which can oxidize biological macromolecules and causes oxidative stress. This stress is generally overcome by the internal antioxidative defense system and stress shielding phytohormones. In this study, effect of 28-HBL was studied on growth and activities of antioxidant enzymes in known hyperaccumulator Raphanus sativus L. (radish) seedlings grown under cadmium (Cd) metal stress. To determine the influence of 28-HBL (0, 10-11, 10-9, 10-7 M) in radish seedlings subjected to Cd (0, 0.5, 1.0, 1.5 mM) stress, the activities of antioxidant enzymes (APOX, CAT, GR, POD and SOD) were analyzed. In addition, length and biomass of radish seedlings was also recorded. Cd toxicity resulted in reduced length, biomass, protein content and activities of antioxidant enzymes. 28-HBL treatments lowered the Cd toxicity by enhancing the activities of antioxidant enzymes, biomass and seedling length. The present study thus suggests a possible role of 28-HBL in amelioration of metal stress by regulating the activities of antioxidant enzymes in radish

Physico-chemical characterization and topological analysis of pathogenesis-related proteins from Arabidopsis thaliana and Oryza sativa using in-silico approaches.

Plants are constantly under the threat of various biotic and abiotic stress conditions and to overcome these stresses, they have evolved multiple mechanisms including systematic accumulation of different phytohormones, phytoalexins and pathogenesis related (PR) proteins. PR proteins are cluster of proteins with low molecular weight which get incited in plants under different stresses. In this paper, in-silico approaches are used to compare the physico-chemical properties of 6 PR proteins (PR1, PR2, PR5, PR9, PR10, PR12) of Arabidopsis thaliana and Oryza sativa. Topological analysis revealed the presence of transmembrane localization of PR2 and absence of transmembrane domain in PR10 of both model plants studied. Amino acid composition shows the dominance of small aliphatic amino acids i.e. alanine, glycine and serine in both plants studied. These results highlights the similarities and differences between PRs of both model plants, which provides clue towards their diversified roles in plants

CpG/CpNpG in the promoter region of <i>O</i>. <i>sativa</i> PRs.

<p>CpG/CpNpG in the promoter region of <i>O</i>. <i>sativa</i> PRs.</p

Pie distribution of identified motifs of <i>A</i>. <i>thaliana</i> and <i>O</i>. <i>sativa</i> PRs from PlantCARE, based on their biological functions.

<p>Pie distribution of identified motifs of <i>A</i>. <i>thaliana</i> and <i>O</i>. <i>sativa</i> PRs from PlantCARE, based on their biological functions.</p

Heat map representation of expression analysis of PR genes at different developmental stages of (a) <i>A</i>. <i>thaliana</i> (b) <i>O</i>. <i>sativa</i>.

<p>Heat map representation of expression analysis of PR genes at different developmental stages of (a) <i>A</i>. <i>thaliana</i> (b) <i>O</i>. <i>sativa</i>.</p

Histogram showing frequencies of occurrence of cis-elements identified using PlantCARE in forward and reverse strands in (a) <i>A</i>. <i>thaliana</i> (b) <i>O</i>. <i>sativa</i> PRs.

<p>Histogram showing frequencies of occurrence of cis-elements identified using PlantCARE in forward and reverse strands in (a) <i>A</i>. <i>thaliana</i> (b) <i>O</i>. <i>sativa</i> PRs.</p