Analysis of Seaweed Extract-induced Transcriptome Leads to Identification of a Negative Regulator of Salt Tolerance in Arabidopsis

Abstract

<jats:p>Successful development of plants resistant to salinity stress is problematic as a result of the complex polygenic natures of salt tolerance. Previously, alkaline extracts of the brown seaweed <jats:italic>Ascophyllum nodosum</jats:italic> have shown promise in enhancing plant tolerance toward abiotic stresses. To understand the underlying molecular mechanisms, the whole genome transcriptome of Arabidopsis undergoing salt stress was analyzed by microarray analysis after treatment with the chemical components of <jats:italic>A. nodosum</jats:italic> extracts (ANE). Treatment with ANE induced many positive regulators of salt tolerance in addition to downregulating numerous other genes. Using T-DNA insertion mutants within these downregulated genes, we examined the potential for a novel source of enhanced NaCl tolerance through removal of negative regulators of NaCl stress responses within Arabidopsis. Several potential target mutations were identified with enhanced salt-tolerant phenotypes. A T-DNA insertion within the promoter of a putative <jats:italic>Pectin Methyl Esterase Inhibitor</jats:italic> (<jats:italic>PMEI</jats:italic>) gene (<jats:italic>At1g62760</jats:italic>) was found to be resistant to salinity stress and was further characterized. This T-DNA insertion mutant was designated as <jats:italic>pmei1-1</jats:italic>. The phenotype of <jats:italic>pmei1-1</jats:italic> seedlings included increased primary root growth in vitro and improved biomass accumulation under NaCl stress. Additionally, modified transcript levels of dehydration-responsive genes, including <jats:italic>RD29A,</jats:italic> were observed in <jats:italic>pmei1-1</jats:italic> plants. Taken together, these results suggest a role for PMEI as a negative regulator of NaCl resistance and that chemical stress-induced transcriptome analysis may lead to identification of additional novel regulators of abiotic stress tolerance in plants, the use of which would have significant implications for agriculture globally.</jats:p>

Plant Cell Walls Tackling Climate Change: Biotechnological Strategies to Improve Crop Adaptations and Photosynthesis in Response to Global Warming

“…They found that salt stress significantly increases PME31 expression and also reported that the knockdown mutant pme31 displayed a hypersensitive phenotype to salt stress in seed germination and post-germination growth with lower expression of several salinity stress-related genes (DREB2A, RD29A and RD29B). An Arabidopsis mutant with reduced expression of a PMEI gene (At1g62760) exhibited reduced sensitivity to salt stress [111]. Phenotypes like enhancement of root growth, increase of fresh weight, and appearance of less chlorosis and necrosis in NaCl treatments in the pmei mutant, suggested that PMEI works as a negative regulator of salinity tolerance.…”

Toward the molecular understanding of the action mechanism of Ascophyllum nodosum extracts on plants

“…Based on undisclosed results of a microarray analysis of Arabidopsis Col-0 plants subjected to 125 mM NaCl in the presence or absence of the organic fraction of an alkaline ANE, genes not previously linked to salinity stress tolerance, of which the expression was downregulated in the presence of ANEs, were functionally analyzed by means of knockout mutants. As such, At1g62760, encoding a putative pectin methylesterase inhibitor, was identified as a novel negative regulator of salt tolerance (Jithesh et al 2012). In a subsequent study, 2-week-old Arabidopsis Col-0 plants subjected to 100 and 150 mM NaCl for 24 h were treated with a 1 g L −1 equivalent of a methanolic ANE fraction (MEA) (Jithesh et al 2018).…”

A commercial seaweed extract structured microbial communities associated with tomato and pepper roots and significantly increased crop yield

“…At the physiological level, these extracts have been found to influence hormones levels that, in turn, influence physiological processes even at very low concentrations (Wally et al, 2013). They impact plant-signalling mechanisms through a multitude of plant processes and cellular modifications including osmotic/oxidative stresses such as salinity, freezing and drought stress (Jithesh et al, 2012). Contrary to the effects of ANE on plant development, the effect of seaweed extracts on the biology of the rhizosphere is still largely unknown.…”