Publications by authors named "Gothandapani Sellamuthu"

8 Publications

  • Page 1 of 1

To exclude or to accumulate? Revealing the role of the sodium HKT1;5 transporter in plant adaptive responses to varying soil salinity.

Plant Physiol Biochem 2021 Dec 19;169:333-342. Epub 2021 Nov 19.

School of Science, Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia.

Arid/semi-arid and coastal agricultural areas of the world are especially vulnerable to climate change-driven soil salinity. Salinity tolerance in plants is a complex trait, with salinity negatively affecting crop yield. Plants adopt a range of mechanisms to combat salinity, with many transporter genes being implicated in Na-partitioning processes. Within these, the high-affinity K (HKT) family of transporters play a critical role in K and Na homeostasis in plants. Among HKT transporters, Type I transporters are Na-specific. While Arabidopsis has only one Na  -specific HKT (AtHKT1;1), cereal crops have a multiplicity of Type I and II HKT transporters. AtHKT1; 1 (Arabidopsis thaliana) and HKT1; 5 (cereal crops) 'exclude' Na from the xylem into xylem parenchyma in the root, reducing shoot Na and hence, confer sodium tolerance. However, more recent data from Arabidopsis and crop species show that AtHKT1;1/HKT1;5 alleles have a strong genetic association with 'shoot sodium accumulation' and concomitant salt tolerance. The review tries to resolve these two seemingly contradictory effects of AtHKT1;1/HKT1;5 operation (shoot exclusion vs shoot accumulation), both conferring salinity tolerance and suggests that contrasting phenotypes are attributable to either hyper-functional or weak AtHKT1;1/HKT1;5 alleles/haplotypes and are under strong selection by soil salinity levels. It also suggests that opposite balancing mechanisms involving xylem ion loading in these contrasting phenotypes exist that require transporters such as SOS1 and CCC. While HKT1; 5 is a crucial but not sole determinant of salinity tolerance, investigation of the adaptive benefit(s) conferred by naturally occurring intermediate HKT1;5 alleles will be important under a climate change scenario.
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http://dx.doi.org/10.1016/j.plaphy.2021.11.030DOI Listing
December 2021

Reference Gene Selection for Normalizing Gene Expression in (Coleoptera: Curculionidae: Scolytinae) Under Different Experimental Conditions.

Front Physiol 2021 27;12:752768. Epub 2021 Oct 27.

Excellent Team for Mitigation (ETM), Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Prague, Czechia.

(Coleoptera: Curculionidae: Scolytinae) is one of the most destructive and economically important forest pests. A better understanding of molecular mechanisms underlying its adaptation to toxic host compounds may unleash the potential for future management of this pest. Gene expression studies could be considered as one of the key experimental approaches for such purposes. A suitable reference gene selection is fundamental for quantitative gene expression analysis and functional genomics studies in . Twelve commonly used reference genes in Coleopterans were screened under different experimental conditions to obtain accurate and reliable normalization of gene expression data. The majority of the 12 reference genes showed a relatively stable expression pattern among developmental stages, tissue-specific, and sex-specific stages; however, some variabilities were observed during varied temperature incubation. Under developmental conditions, the (β) was the most stable reference gene, followed by () and (). In sex-specific conditions, , β, and were the most stable reference genes. In contrast, different sets of genes were shown higher stability in terms of expression under tissue-specific conditions, i.e., and in head tissue, and in the fat body, and in the gut. Under varied temperatures, β and were most stable, whereas and displayed the highest expression stability after Juvenile Hormone III treatment. The findings were validated further using real-time quantitative reverse transcription PCR (RT-qPCR)-based target gene expression analysis. Nevertheless, the present study delivers a catalog of reference genes under varied experimental conditions for the coleopteran forest pest and paves the way for future gene expression and functional genomic studies on this species.
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http://dx.doi.org/10.3389/fphys.2021.752768DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8580292PMC
October 2021

Reduced apoplastic barriers in tissues of shoot-proximal rhizomes of Oryza coarctata are associated with Na + sequestration.

J Exp Bot 2021 Oct 4. Epub 2021 Oct 4.

Plant Molecular Biology Laboratory, M.S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, Chennai, India.

Oryza coarctata is the only wild rice species with significant salinity tolerance. The present work examines the role of the substantial rhizomatous tissues of O. coarctata in conferring salinity tolerance. Transition to an erect phenotype (shoot emergence) from prostrate growth of rhizome tissues is characterized by marked lignification and suberization of supporting sclerenchymatous tissue, epidermis and bundle sheath cells in aerial shoot proximal nodes and internodes in O. coarctata. With salinity however, aerial shoot proximal internodal tissues show reductions in lignification and suberization, most likely related to re-direction of carbon flux towards synthesis of osmporotectant proline. Concurrent with hypolignification and reduced suberization, the aerial rhizomatous biomass of O. coarctata appears to have evolved mechanisms to store Na + in these specific tissues under salinity. This was confirmed by histochemical staining, RT-qPCR expression patterns of genes involved in lignification/suberization, Na +, K + contents of internodal tissues as well as non-invasive microelectrode ion flux measurements of NaCl-induced net Na +, K + and H + flux profiles of aerial nodes. In O. coarctata, aerial proximal internodes appear to act as 'traffic controllers', sending required amounts of Na +, K + into developing leaves for osmotic adjustment and turgor-driven growth while more deeply positioned internodes assume a Na + buffering/storage role.
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http://dx.doi.org/10.1093/jxb/erab440DOI Listing
October 2021

Distinct Evolutionary Origins of Intron Retention Splicing Events in Antiporter Transcripts Relate to Sequence Specific Distinctions in Species.

Front Plant Sci 2020 11;11:267. Epub 2020 Mar 11.

Plant Molecular Biology Laboratory, M.S. Swaminathan Research Foundation, Chennai, India.

The genome of Asian cultivated rice ( L.) shows the presence of six organelle-specific and one plasma membrane () NHX-type cation proton antiporters. Of these, vacuolar-localized is extensively characterized. The genus consists of 27 species and 11 genome-types, with cultivated rice, diploid , having an AA-type genome. orthologous regions (gene organization, 5' upstream cis elements, amino acid residues/motifs) from closely related AA genomes cluster distinctly from regions from more ancestral BB, FF and KKLL genomes. These sequence-specific distinctions also extend to two separate intron retention (IR) events involving transcripts that occur at the 5' and 3' ends of the NHX1 transcripts. We demonstrate that the IR event involving the 5' UTR is present only in more recently evolved AA genomes while the IR event governing retention of the 13th intron of (terminal intron) is more ancient in origin, also occurring in halophytic wild rice, (KKLL). We also report presence of a retro-copy of the cDNA in the genome of (). Preferential species and tissue specific up- or down-regulation of the correctly spliced transcript/5' UTR/13th intron-retaining splice variants under salinity was observed. The implications of IR on mRNA stability and ORF diversity in spp. is discussed.
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http://dx.doi.org/10.3389/fpls.2020.00267DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7078337PMC
March 2020

Microhair on the adaxial leaf surface of salt secreting halophytic Oryza coarctata Roxb. show distinct morphotypes: Isolation for molecular and functional analysis.

Plant Sci 2019 Aug 7;285:248-257. Epub 2019 May 7.

Plant Molecular Biology Laboratory, M.S. Swaminathan Research Foundation (MSSRF), III Cross Street, Taramani Institutional Area, Chennai, 600 113, India. Electronic address:

Halophytic Oryza coarctata is a good model system to examine mechanisms of salinity tolerance in rice. O. coarctata leaves show the presence of microhairs in adaxial leaf surface furrows that secrete salt under salinity. However, detailed molecular and physiological studies of O. coarctata microhairs are limited due to their relative inaccessibility. This work presents a detailed characterization of O. coarctata leaf features. O. coarctata has two types of microhairs on the adaxial leaf surface: longer microhairs (three morphotypes) lining epidermal furrow walls and shorter microhairs (reported first time) arising from bulliform cells. Microhair morphotypes include (i) finger-like, tubular structures, (ii) tubular hairs with bilobed and flattened heads and (iii) bi-or trifurcated hairs. The unicellular nature of microhairs was confirmed by propidium iodide (PI) staining. An efficient method for the isolation and enrichment of O. coarctata microhairs is presented (yield averaging ˜2 × 10/g leaf tissue). The robustness of the microhair isolation procedure was confirmed by subsequent viability staining (PI), total RNA isolation and RT-PCR amplification of O. coarctata trichome-specific WUSCHEL-related homeobox 3B (OcWox3B) and transporter gene-specific cDNA sequences. The present microhair isolation work from O. coarctata paves the way for examining genes involved in ion secretion in this halophytic wild rice model.
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http://dx.doi.org/10.1016/j.plantsci.2019.05.004DOI Listing
August 2019

CRISPR for Crop Improvement: An Update Review.

Front Plant Sci 2018 17;9:985. Epub 2018 Jul 17.

Plant Molecular Biology Laboratory, Department of Biotechnology, M. S. Swaminathan Research Foundation, Chennai, India.

The availability of genome sequences for several crops and advances in genome editing approaches has opened up possibilities to breed for almost any given desirable trait. Advancements in genome editing technologies such as zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs) has made it possible for molecular biologists to more precisely target any gene of interest. However, these methodologies are expensive and time-consuming as they involve complicated steps that require protein engineering. Unlike first-generation genome editing tools, CRISPR/Cas9 genome editing involves simple designing and cloning methods, with the same Cas9 being potentially available for use with different guide RNAs targeting multiple sites in the genome. After proof-of-concept demonstrations in crop plants involving the primary CRISPR-Cas9 module, several modified Cas9 cassettes have been utilized in crop plants for improving target specificity and reducing off-target cleavage (e.g., Nmcas9, Sacas9, and Stcas9). Further, the availability of Cas9 enzymes from additional bacterial species has made available options to enhance specificity and efficiency of gene editing methodologies. This review summarizes the options available to plant biotechnologists to bring about crop improvement using CRISPR/Cas9 based genome editing tools and also presents studies where CRISPR/Cas9 has been used for enhancing biotic and abiotic stress tolerance. Application of these techniques will result in the development of non-genetically modified (Non-GMO) crops with the desired trait that can contribute to increased yield potential under biotic and abiotic stress conditions.
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http://dx.doi.org/10.3389/fpls.2018.00985DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6056666PMC
July 2018

An Environmentally Friendly Engineered Azotobacter Strain That Replaces a Substantial Amount of Urea Fertilizer while Sustaining the Same Wheat Yield.

Appl Environ Microbiol 2017 Aug 17;83(15). Epub 2017 Jul 17.

School of Biotechnology, Jawaharlal Nehru University, New Delhi, India

In our endeavor to improve the nitrogen fixation efficiency of a soil diazotroph that would be unaffected by synthetic nitrogenous fertilizers, we have deleted a part of the negative regulatory gene and constitutively expressed the positive regulatory gene in the chromosome of CBD15, a strain isolated from the local field soil. No antibiotic resistance gene or other foreign gene was present in the chromosome of the engineered strain. Wheat seeds inoculated with this engineered strain, which we have named HKD15, were tested for 3 years in pots and 1 year in the field. The yield of wheat was enhanced by ∼60% due to inoculation of seeds by HKD15 in the absence of any urea application. Ammonium only marginally affected acetylene reduction by the engineered strain. When urea was also applied, the same wheat yield could be sustained by using seeds inoculated with HKD15 and using ∼85 kg less urea (∼40 kg less nitrogen) than the usual ∼257 kg urea (∼120 kg nitrogen) per hectare. Wheat plants arising from the seeds inoculated with the engineered strain exhibited far superior overall performance, had much higher dry weight and nitrogen content, and assimilated molecular N much better. A nitrogen balance experiment also revealed much higher total nitrogen content. Indole-3-acetic acid (IAA) production by the wild type and that by the engineered strain were about the same. Inoculation of the wheat seeds with HKD15 did not adversely affect the microbial population in the field rhizosphere soil. Application of synthetic nitrogenous fertilizers is a standard agricultural practice to augment crop yield. Plants, however, utilize only a fraction of the applied fertilizers, while the unutilized fertilizers cause grave environmental problems. Wild-type soil diazotrophic microorganisms cannot replace synthetic nitrogenous fertilizers, as these reduce atmospheric nitrogen very inefficiently and almost none at all in the presence of added nitrogenous fertilizers. If the nitrogen-fixing ability of soil diazotrophs could be improved and sustained even in the presence of synthetic nitrogenous fertilizers, then a mixture of the bacteria and a reduced quantity of chemical nitrogenous fertilizers could be employed to obtain the same grain yield but at a much-reduced environmental cost. The engineered strain that we have reported here has considerably enhanced nitrogen fixation and excretion abilities and can replace ∼85 kg of urea per hectare but sustain the same wheat yield, if the seeds are inoculated with it before sowing.
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http://dx.doi.org/10.1128/AEM.00590-17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5514683PMC
August 2017

GhDRIN1, a novel drought-induced gene of upland cotton (Gossypium hirsutum L.) confers abiotic and biotic stress tolerance in transgenic tobacco.

Biotechnol Lett 2015 Apr 21;37(4):907-19. Epub 2014 Nov 21.

National Research Centre on Plant Biotechnology, LBS Building, Pusa Campus, New Delhi, 110012, India.

A novel stress tolerance cDNA fragment encoding GhDRIN1 protein was identified and its regulation was studied in cotton boll tissues and seedlings subjected to various biotic and abiotic stresses. Phylogenetic and conserved domain prediction indicated that GhDRIN1 was annotated with a hypothetical protein of unknown function. Subcellular localization showed that GhDRIN1 is localized in the chloroplasts. The promoter sequence was isolated and subjected to in silico study. Various cis-acting elements responsive to biotic and abiotic stresses and hormones were found. Transgenic tobacco seedlings exhibited better growth on amended MS medium and showed minimal leaf damage in insect bioassays carried out with Helicoverpa armigera larvae. Transgenic tobacco showed better tolerance to water-deficit and fast recovered upon rewatering. Present work demonstrated that GhDRIN1, a novel stress tolerance gene of cotton, positively regulates the response to biotic and abiotic stresses in transgenic tobacco.
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http://dx.doi.org/10.1007/s10529-014-1733-9DOI Listing
April 2015
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