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High-level expression of sugar inducible gene2 (HSI2) is a negative regulator of drought stress tolerance in Arabidopsis.

ABSTRACT: BACKGROUND: HIGH-LEVEL EXPRESSION OF SUGAR INDUCIBLE GENE2 (HSI2), also known as VAL1, is a B3 domain transcriptional repressor that acts redundantly with its closest relative, HSI2-LIKE1 (HSL1), to suppress the seed maturation program following germination. Mutant hsi2 hsl1 seedlings are arrested early in development and differentially express a number of abiotic stress-related genes. To test the potential requirement for HSI2 during abiotic stress, hsi2 single mutants and plants overexpressing HSI2 were subjected to simulated drought stress by withholding watering, and characterized through physiological, metabolic and gene expression studies. RESULTS: The hsi2 mutants demonstrated reduced wilting and maintained higher relative water content than wild-type after withholding watering, while the overexpressing lines displayed the opposite phenotype. The hsi2 mutant displayed lower constitutive and ABA-induced stomatal conductance than wild-type and accumulated lower levels of ABA metabolites and several osmolytes and osmoprotectants following water withdrawal. Microarray comparisons between wild-type and the hsi2 mutant revealed that steady-state levels of numerous stress-induced genes were up-regulated in the mutant in the absence of stress but down-regulated at visible wilting. Plants with altered levels of HSI2 responded to exogenous application of ABA and a long-lived ABA analog, but the hsi2 mutant did not show altered expression of several ABA-responsive or ABA signalling genes 4 hr after application. CONCLUSIONS: These results implicate HSI2 as a negative regulator of drought stress response in Arabidopsis, acting, at least in part, by regulating transpirational water loss. Metabolic and global transcript profiling comparisons of the hsi2 mutant and wild-type plants do not support a model whereby the greater drought tolerance observed in the hsi2 mutant is conferred by the accumulation of known osmolytes and osmoprotectants. Instead, data are consistent with mutants experiencing a relatively milder dehydration stress following water withdrawal.

SUBMITTER: Sharma N

PROVIDER: S-EPMC3893512 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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High-level expression of sugar inducible gene2 (HSI2) is a negative regulator of drought stress tolerance in Arabidopsis.

Sharma Nirmala N Bender Yarnel Y Boyle Kerry K Fobert Pierre R PR

BMC plant biology 20131029

<h4>Background</h4>HIGH-LEVEL EXPRESSION OF SUGAR INDUCIBLE GENE2 (HSI2), also known as VAL1, is a B3 domain transcriptional repressor that acts redundantly with its closest relative, HSI2-LIKE1 (HSL1), to suppress the seed maturation program following germination. Mutant hsi2 hsl1 seedlings are arrested early in development and differentially express a number of abiotic stress-related genes. To test the potential requirement for HSI2 during abiotic stress, hsi2 single mutants and plants overexp ...[more]

PMID: 24168327

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Project description:BACKGROUND: SUMO (Small Ubiquitin related Modifier) conjugation is a post translational regulatory process found in all eukaryotes, mediated by SUMO activating enzyme, SUMO conjugating enzyme, and SUMO ligase for the attachment of SUMO to its target protein. Although the mechanism for regulation of SUMO conjugation pathway genes under abiotic stress has been studied to certain extent, the role of SUMO conjugating enzyme in improving abiotic stress tolerance to plant is largely unexplored. Here, we have characterized a SUMO conjugating enzyme gene 'SaSce9' from a halophytic grass Spartina alterniflora and investigated its role in imparting abiotic stress tolerance. RESULTS: SaSce9 gene encodes for a polypeptide of 162 amino acids with a molecular weight of ~18 kD and isoelectric point 8.43. Amino acid sequence comparisons of SaSce9 with its orthologs from other plant species showed high degree (~85-93%) of structural conservation among each other. Complementation analysis using yeast SCE mutant, Ubc9, revealed functional conservation of SaSce9 between yeast and S. alterniflora. SaSce9 transcript was inducible by salinity, drought, cold, and exogenously supplied ABA both in leaves and roots of S. alterniflora. Constitutive overexpression of SaSce9 in Arabidopsis through Agrobacterium mediated transformation improved salinity and drought tolerance of Arabidopsis. SaSce9 overexpressing Arabidopsis plants retained more chlorophyll and proline both under salinity and drought stress. SaSce9 transgenic plants accumulated lower levels of reactive oxygen under salinity stress. Expression analysis of stress responsive genes in SaSce9 Arabidopsis plants revealed the increased expression of antioxidant genes, AtSOD and AtCAT, ion antiporter genes, AtNHX1 and AtSOS1, a gene involved in proline biosynthesis, AtP5CS, and a gene involved in ABA dependent signaling pathway, AtRD22. CONCLUSIONS: These results highlight the prospect of improving abiotic stress tolerance in plants through genetic engineering of the sumoylation pathway. The study provides evidence that the overexpression of SaSce9 in plant can improve salinity and drought stress tolerance by protecting the plant through scavenging of ROS, accumulation of an osmolyte, proline, and expression of stress responsive genes. In addition, this study demonstrates the potential of the halophyte grass S. alterniflora as a reservoir of abiotic stress related genes for crop improvement.

Dataset Information

High-level expression of sugar inducible gene2 (HSI2) is a negative regulator of drought stress tolerance in Arabidopsis.

Publications

High-level expression of sugar inducible gene2 (HSI2) is a negative regulator of drought stress tolerance in Arabidopsis.

Similar Datasets

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