Development Of Abiotic Stress Tolerance Research Articles

Overexpression of the alfalfa DnaJ-like protein (MsDJLP) gene enhances tolerance to chilling and heat stresses in transgenic tobacco plants.

Heat shock proteins (HSPs) are generally considered as important molecular chaperones; they are known to perform critical functions in plant development and abiotic stress response processes. In this study, we examined the role of a HSP, the Medicago sativa DnaJ-like protein (MsDJLP), in alfalfa and its potential application for the development of abiotic stress tolerance in plants. We found that expression of the MsDJLP gene was induced by chilling (4 °C) and heat (42 °C), but not by cadmium (500 µM) or arsenic (500 µM) stresses. We then cloned the MsDJLP gene downstream of the strong constitutive CaMV 35S promoter and transformed it into tobacco plants. Ectopic expression of MsDJLP conferred enhanced tolerance to both chilling and heat stresses in transgenic tobacco plants. Under chilling stress, the transgenic tobacco plants showed lower H2O2 accumulation and electrolyte leakage (EL) activity, and better photosystem II efficiency than wild-type (WT) plants, indicating that photoinhibition was less severe in transgenic compared to WT plants. Following heat treatment, the transgenic plants showed better relative chlorophyll and water contents, and lower malondialdehyde accumulation than WT plants. Our study provides evidence for a pivotal role of MsDJLP for chilling and heat stress tolerance in transgenic tobacco plants.

MiRNAs: Major modulators for crop growth and development under abiotic stresses.

Cumulatively, biotic and abiotic stresses of various magnitudes can decrease the production of crops by 70%. miRNAs have emerged as a genetic tool with enormous potential that can be exploited to understand stress tolerance at the molecular level and eventually regulate stress in crops. Plant miRNA targets frequently fit into diverse families of TFs that control the expression of genes related to a certain trait. As key machinery in gene regulatory networks, it is agreed that a broad understanding of miRNAs will greatly increase our understanding of plant responses to environmental stresses. miRNA-led stress regulatory networks are being considered as novel tools for the development of abiotic stress tolerance in crops. At this time, we need to expand our knowledge about the modulatory role of miRNAs during environmental fluctuations. It has become exceedingly clear that with increased understanding of the role of miRNAs during stress, the techniques for using miRNA-mediated gene regulation to enhance plant stress tolerance will become more effective and reliable. In this review we present: (1) miRNAs as a potential avenue for the modulation of abiotic stresses, and (2) summarize the research progress regarding plant responses to stress. Current progress is explained through discussion of the identification and validation of several miRNAs that enhance crop tolerance of salinity, drought, etc., while missing links on different aspects of miRNAs related to abiotic stress tolerance are noted.

Molecular Strategies for Development of Abiotic Stress Tolerance in Plants

Molecular Strategies for Development of Abiotic Stress Tolerance in Plants

Meet the Editorial Board Members:

Dr. de Magalhaes graduated in Microbiology in 1999 from the Escola Superior de Biotecnologia in his hometown of Porto, Portugal, and then obtained his PhD in 2004 from the University of Namur in Belgium, where he worked in the Ageing and Stress Group led by Dr Olivier Toussaint. Following a postdoc with genomics pioneer Prof George Church at Harvard Medical School in Boston, USA, in 2008 Dr de Magalhaes joined the University of Liverpool to develop his own group on genomic approaches to ageing. Now a senior lecturer, Dr de Magalhaes leads the Integrative Genomics of Ageing Group (http://pcwww.liv.ac.uk/~aging/) which focuses on understanding the genetic, cellular, and molecular mechanisms of ageing. The group’s research integrates different strategies but its focal point is developing and applying experimental and computational methods that help bridge the gap between genotype and phenotype, a major challenge of the post-genome era, and help decipher the human genome and how it regulates complex processes like ageing. Dr. Girdhar K. Pandey received B.Sc (Hon.) in Biochemistry from Delhi University and M.Sc. in Biotechnology from Banaras Hindu University (BHU), India. He was awarded Ph.D. degree from Jawaharlal Nehru University (JNU) and then pursued post-doctoral career at the Department of Plant and Microbial Biology, University of California at Berkeley. There, he extended the work in the field of calcium mediated signaling in Arabidopsis by studying CBL-CIPK, phosphatases, channels/transporters, and transcription factors involved in abiotic stresses. Currently, he is working as Associate Professor in the Department of Plant Molecular Biology, Delhi University South Campus. His group’s research interest is to understand the detail mechanistic interplay of signal transduction networks in plant under mineral nutrient deficiency (mostly K+, Ca2+ and NO3-) and abiotic stresses such as drought, salinity and oxidative stresses. His laboratory is working on the coding and decoding of mineral nutrient deficiency and abiotic stress signals by studying several signaling components such as phospholipases (PLA, PLC, and PLD), calcium sensors such as calcineurin B-like (CBL) and CBL-interacting protein kinases (CIPK), phosphatases (mainly PP2C and DSP), transcription factors (AP2-domain containing or ERF, WRKY), transporters and channels proteins (K+, Ca2+ and NO3- channels/transporters), small GTPases, and Armadillo domain containing proteins in both Arabidopsis and rice. The long-term goal of his research group is to establish the mechanistic interplay and cross talk of mineral nutrient deficient conditions and different abiotic stress signaling cascades in Arabidopsis and rice model plants by using the advance tools of genomics, genetics, cell biology, biochemistry and physiology with greater emphasis on functional genomics and proteomic approaches. This will ultimately help to dissect the interaction of several pathways to converge and diverge at some points and mapping of the “Signaling Interactome” under stress conditions. Dr. Pandey published 40 research articles in the reputed international peer-reviewed journals such as The Plant Cell, PNAS, JBC, Plant Journal, Plant Physiology, Cell Research, Molecular Plants, DNA Research, BMC Genomic, PLoS One, European Journal of Biochemistry, Plant Science, Current Genomics, FEBS Journal, Fronteir in Plant Sciences and others. Some of his research work in the field of development of abiotic stress tolerance has been patented in the USA. Visit his Lab web-page for further information about research work: http://sites.google.com/site/gkplab/home; http://www.dpmb.ac.in/index.php?page=girdhar-pandey

Isolation, in silico characterization, localization and expression analysis of abiotic stress-responsive rice G-protein β subunit (RGB1)

Heterotrimeric G-proteins constitute the classical signaling paradigm along with their cognate G-protein coupled receptors (GPCRs) and appropriate downstream effectors. G-protein complex is composed of highly conserved Gα, Gβ, and Gγ subunits. In the present study, we have characterized the cis-regulatory elements of the promoter, signature motifs, transcript profile in response to abiotic stresses, and sub-cellular localization of G-protein β subunit RGB1(I) from Indica rice. The RGB1(I) promoter sequence has various stress-related cis-regulatory elements suggesting its role in abiotic stress signaling. Presence of six WD-40 repeat signature motifs in RGB1(I) suggest its role in exchange of GDP by GTP in Gα subunit and receptor recognition. Presence of multiple N-myristoylation consensus sites in RGB1(I) protein sequence, which is necessary for membrane localization of protein, confirms the association of RGB1(I) in plasma membrane. Extrinsic association of RGB1(I) with plasma membrane seems essential for its role in regulation of signaling pathways and adaptation to high salt stress. We report the sub-cellular localization of RGB1(I) in plasma membrane, cytosol and nucleus. The localization of RGB1(I) in nucleus supports its possible interaction with transcription factors regulating the expression of salt stress responsive genes. The RGB1(I) transcript was upregulated under KCl, cold, dehydration and micronutrient (Mn2+ and Zn2+) stress. However, transcript variation under elevated temperature, ABA, NaCl, and toxic heavy metals (viz. arsenite, arsenate, cadmium and lead) was not encouraging. These evidences indicate an active and significant role of RGB1(I) in the regulation of abiotic stresses in rice and propound its possible exploitation in the development of abiotic stress tolerance in crops.

Rice heterotrimeric G-protein alpha subunit (RGA1): In silico analysis of the gene and promoter and its upregulation under abiotic stress

Heterotrimeric G-protein complexes (Gα, Gβ and Gγ) operate at the apex of diverse signal transduction systems along with their cognate transmembrane G-protein coupled receptors (GPCRs) and appropriate downstream effectors in the plant. Rice Gα in response to stress has not been well studied. Here, we report the in silico analysis of Gα subunit from Oryza sativa cv. Indica group Swarna [RGA1(I), accession number HQ634688], its promoter and its transcript upregulation in response to abiotic stresses. Genomic sequence of RGA1(I) contains thirteen exonic and twelve intronic segments. Phylogenetic analysis of RGA1(I) demonstrated high homology with Sorghum and maize and is distantly related to barley and wheat. Promoter sequence analysis of RGA1(I) confirms the presence of stress-related cis-regulatory elements viz. ABA, MeJAE, ARE, GT-1 boxes and LTR suggesting its active and possible independent roles in abiotic stress signalling. Expasy PROSITE database of protein families and domains revealed important motifs, patterns and biologically significant sites in RGA1(I). Three dimensional structure of RGA1(I) protein predicted by I-TASSER server and its stereochemical qualities were validated by PROCHECK and QMEAN server indicating the acceptability of the predicted model. The transcript profiling of RGA1(I) showed upregulation following NaCl, cold and drought stress. Under elevated temperature, its transcript was down regulated. Heavy metal(loid)s stress showed rhythmic and strong upregulation. It showed a rhythmic response in ABA stress. These findings provide a critical evidence for its active role in regulation of abiotic stresses in rice. These findings suggest its possible exploitation in the development of abiotic stress tolerance in crops.

Improved salinity tolerance of rice through cell type-specific expression of AtHKT1;1.

Previously, cell type-specific expression of AtHKT1;1, a sodium transporter, improved sodium (Na+) exclusion and salinity tolerance in Arabidopsis. In the current work, AtHKT1;1, was expressed specifically in the root cortical and epidermal cells of an Arabidopsis GAL4-GFP enhancer trap line. These transgenic plants were found to have significantly improved Na+ exclusion under conditions of salinity stress. The feasibility of a similar biotechnological approach in crop plants was explored using a GAL4-GFP enhancer trap rice line to drive expression of AtHKT1;1 specifically in the root cortex. Compared with the background GAL4-GFP line, the rice plants expressing AtHKT1;1 had a higher fresh weight under salinity stress, which was related to a lower concentration of Na+ in the shoots. The root-to-shoot transport of 22Na+ was also decreased and was correlated with an upregulation of OsHKT1;5, the native transporter responsible for Na+ retrieval from the transpiration stream. Interestingly, in the transgenic Arabidopsis plants overexpressing AtHKT1;1 in the cortex and epidermis, the native AtHKT1;1 gene responsible for Na+ retrieval from the transpiration stream, was also upregulated. Extra Na+ retrieved from the xylem was stored in the outer root cells and was correlated with a significant increase in expression of the vacuolar pyrophosphatases (in Arabidopsis and rice) the activity of which would be necessary to move the additional stored Na+ into the vacuoles of these cells. This work presents an important step in the development of abiotic stress tolerance in crop plants via targeted changes in mineral transport.

Development of abiotic stress tolerance via bZIP-type transcription factor LIP19 in common wheat

Cereal lip19 genes encoding bZIP-type transcription factors are assumed to play a regulatory role in gene expression during the cold acclimation process. However, no direct evidence shows an association of LIP19-type bZIPs with stress tolerance or activation of stress-responsive Cor/Lea genes. To understand the molecular basis of development of abiotic stress tolerance through the LIP19 transcription factor, a wheat lip19 homologue, Wlip19, was isolated and characterized. Wlip19 expression was activated by low temperature in seedlings and was higher in a freezing-tolerant cultivar than in a freezing-sensitive one. Wlip19 also responded to drought and exogenous ABA treatment. Wlip19-expressing transgenic tobacco showed a significant increase in abiotic stress tolerance, especially freezing tolerance. Expression of a GUS reporter gene under the control of promoter sequences of four wheat Cor/Lea genes, Wdhn13, Wrab17, Wrab18, and Wrab19, was enhanced by Wlip19 expression in wheat callus and tobacco plants. These results indicate that WLIP19 acts as a transcriptional regulator of Cor/Lea genes in the development of abiotic stress tolerance. Moreover, direct protein-protein interaction between WLIP19 and a wheat OBF1 homologue TaOBF1, another bZIP-type transcription factor, was observed, suggesting that this interaction is conserved in cereals.