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Subject: search.filters.subject.Salinity stress

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    Genome wide investigation and transcriptional profiling of SWEET genes in two contrasting cultivars of foxtail millet under abiotic stresses
    (Elsevier B.V., 2025) Singh, Jitender; Singh, Kajol BM.; Sutar, Rashmi Ranjan; Kumar, Angad; Prasad, Manoj; Thakur, Jitendra K.
    The SWEET (Sugars will eventually be exported transporter) gene family is an important class of sugar transporters that regulates diverse aspects of plant physiology such as apoplastic phloem loading, plant-pathogen interactions and plant responses to abiotic stresses. While majority of the studies on SWEET family in plants have been performed in C3 species, there are limited reports on C4 plants. In this study we conducted genome wide investigation of the SWEET gene family in foxtail millet, a naturally stress tolerant C4 crop. In-silico analysis identified 24 SWEET genes in foxtail millet genome that were classified into 4 distinct clades. Domain analysis revealed the presence of conserved MtN3_slv/PQ-loop domains in all identified SWEET proteins. Interestingly, many SWEET proteins also harboured the prokaryotic SemiSWEET/PQ-loop domain suggesting an evolutionary link to their prokaryotic Semi-SWEET ancestors. In-silico analysis predicted the presence of abscisic acid and drought responsive cis-elements in the promoter region of SWEET genes. Transcriptional analysis under control, drought, and salinity stress revealed differential expression patterns of SWEET genes in stress resistant and stress susceptible foxtail millet cultivars. Moreover, the differential expression of SWEET genes altered the soluble sugar content in leaves and roots under stress conditions suggesting altered carbon re-allocation between source and sink tissues. This study significantly advances our understanding of the SWEET gene family in C4 plants, particularly in foxtail millet, and provides insights into its role in stress tolerance mechanisms and carbohydrate re-allocation under stress conditions.
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    Ectopic overexpression of cytosolic ascorbate peroxidase gene (Apx1) improves salinity stress tolerance in Brassica juncea by strengthening antioxidative defense mechanism
    (Springer Nature, 2020) Saxena, Saurabh C.; Salvi, Prafull; Kamble, Nitin Uttam; Joshi, Pankaj K.; Majee, Manoj; Arora, Sandeep
    Salinity stress is considered to be a key constrain that reduces the crop productivity by impairing plant growth and development. During salt stress condition, an underlying mechanism for reduction in crop yield is increase in ROS level that can potentially harm cellular macromolecules, leading to disruption of essential physiological and biochemical processes. Plants possess a complex antioxidative defense machinery for scavenging these ROS. Ascorbate peroxidase (APX, E.C. 1.11.1.11), is a crucial antioxidant enzyme involved in Ascorbate–Glutathione pathway that primarily detoxifies the negative impact of H2O2 in cell. The efficient scavenging of H2O2 is a prerequisite for enhanced tolerance to salinity stress. Here, we have inspected whether over-expression of APX could provide protection against salinity stress. Cytosolic ascorbate peroxidase (Apx1) gene, isolated from Arabidopsis thaliana, was chosen as the candidate gene for strengthening the antioxidative defense system of Brassica juncea. Physiological parameters were employed to analyze the growth status of transgenic plants. Leaf disc assay was done to evaluate the salinity stress tolerance potential of transgenic plants, using several physiological and biochemical parameters. Under salinity stress, the transgenic plants performed well as compared to their non-transgenic counterparts; as revealed through greater proline accumulation, increased chlorophyll stability index, lower chlorophyll a/b ratio, and higher antioxidative enzyme activities. Further, the lower H2O2 levels were well correlated with lesser membrane damage as measured through MDA content. Collectively, our results clearly depicted that ectopic overexpression of AtApx1 gene was able to confer salinity stress tolerance by strengthening the antioxidative defense system in B. juncea.
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    Concurrent overexpression of rice G-protein β and γ subunits provide enhanced tolerance to sheath blight disease and abiotic stress in rice
    (Springer Nature Publishing AG, 2019) Swain, Durga Madhab; Sahoo, Ranjan Kumar; Chandan, Ravindra Kumar; Ghosh, Srayan; Kumar, Rahul; Jha, Gopaljee; Tuteja, Narendra
    The heterotrimeric G-proteins act as signalling molecules and modulate various cellular responses including stress tolerance in eukaryotes. The gamma (γ) subunit of rice G-protein (RGG1) was earlier reported to promote salinity stress tolerance in rice. In the present study, we report that a rice gene-encoding beta (β) subunit of G-protein (RGB1) gets upregulated during both biotic (upon a necrotrophic fungal pathogen, Rhizoctonia solani infection) and drought stresses. Markerfree transgenic IR64 rice lines that simultaneously overexpress both RGB1 and RGG1 genes under CaMV35S promoter were raised. The overexpressing (OE) lines showed enhanced tolerance to R. solani infection and salinity/drought stresses. Several defense marker genes including OsMPK3 were signifcantly upregulated in the R. solani-infected OE lines. We also found the antioxidant machineries to be upregulated during salinity as well as drought stress in the OE lines. Overall, the present study provides evidence that concurrent overexpression of G-protein subunits (RGG1 and RGB1) impart multiple (both biotic and abiotic) stress tolerance in rice which could be due to the enhanced expression of stress-marker genes and better management of reactive oxygen species (ROS)-scavenging/photosynthetic machinery. The current study suggests an improved approach for simultaneous improvement of biotic and abiotic stress tolerance in rice which remains a major challenge for its sustainable cultivation.
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    Overexpression of a cell wall damage induced transcription factor, OsWRKY42, leads to enhanced callose deposition and tolerance to salt stress but does not enhance tolerance to bacterial infection
    (BioMed Central Ltd, 2018) Pillai, Shakuntala E.; Kumar, Chandan; Patel, Hitendra K.; Sonti, Ramesh V.
    Background: Members of the WRKY gene family play important roles in regulating plant responses to abiotic and biotic stresses. Treatment with either one of the two different cell wall degrading enzymes (CWDEs), LipaseA and CellulaseA, induces immune responses and enhances the expression of OsWRKY42 in rice. However, the role of OsWRKY42 in CWDE induced immune responses is not known. Results: Expression of the rice transcription factor OsWRKY42 is induced upon treatment of rice leaves with CWDEs, wounding and salt. Overexpression of OsWRKY42 leads to enhanced callose deposition in rice and Arabidopsis but this does not enhance tolerance to bacterial infection. Upon treatment with NaCl, Arabidopsis transgenic plants expressing OsWRKY42 exhibited high levels of anthocyanin and displayed enhanced tolerance to salt stress. Treatment with either cellulase or salt induced the expression of several genes involved in JA biosynthesis and response in Arabidopsis. Ectopic expression of OsWRKY42 results in reduced expression of cell wall damage and salt stress induced jasmonic acid biosynthesis and response genes. OsWRKY42 expressing Arabidopsis lines exhibited enhanced tolerance to methyl jasmonate mediated growth inhibition. Conclusion: The results presented here suggest that OsWRKY42 regulates plant responses to either cell wall damage or salinity stress by acting as a negative regulator of jasmonic acid mediated responses.