Overexpression of soybean ubiquitin-conjugating enzyme gene GmUBC2 confers enhanced drought and salt tolerance through modulating abiotic stress-responsive gene expression in Arabidopsis

Abstract

Previous studies have shown that ubiquitination plays important roles in plant abiotic stress responses. In the present study, the ubiquitin-conjugating enzyme gene GmUBC2, a homologue of yeast RAD6, was cloned from soybean and functionally characterized. GmUBC2 was expressed in all tissues in soybean and was up-regulated by drought and salt stress. Arabidopsis plants overexpressing GmUBC2 were more tolerant to salinity and drought stresses compared with the control plants. Through expression analyses of putative downstream genes in the transgenic plants, we found that the expression levels of two ion antiporter genes AtNHX1 and AtCLCa, a key gene involved in the biosynthesis of proline, AtP5CS, and the copper chaperone for superoxide dismutase gene AtCCS, were all increased significantly in the transgenic plants. These results suggest that GmUBC2 is involved in the regulation of ion homeostasis, osmolyte synthesis, and oxidative stress responses. Our results also suggest that modulation of the ubiquitination pathway could be an effective means of improving salt and drought tolerance in plants through genetic engineering.

Salt-induced root protein profile changes in seedlings of maize inbred lines with differing salt tolerances

“…These proteins, identified as proteasomes, were up-regulated under salt stress in salt-tolerant 'N1145' and down-regulated in salt-sensitive 'D340'. In previous studies, the involvement of proteolytic pathway proteins such as proteases in salt tolerance has been inferred on the basis of increases in transcript levels or enzyme activities (Manivannan et al, 2008;Li et al, 2009;Zhou et al, 2010). Our results indicate that a plant might increase its salt tolerance by enhancing its protein proteolysis capacity.…”

HIRA, a Conserved Histone Chaperone, Plays an Essential Role in Low-dose Stress Response via Transcriptional Stimulation in Fission Yeast

“…Moreover, in the fission yeast, histone H2B ubiquitylation is required for transcriptional elongation, and HIRA mutations are synthetically lethal with htb1-K119R, the mutation in the conserved ubiquitin acceptor site of histone H2B, indicating the role of histone H2B ubiquitylation in chromatin assembly during transcription (61). Indeed, the overexpression of ubiquitin-conjugating enzyme gene confers enhanced stress tolerance in plants (62) and RAD6, which encodes ubiquitin-conjugating enzyme in the budding yeast, is involved in the heat shock induction of bleomycin resistance (cross-tolerance) (63). Transcriptional regulation through HIRA recruitment may be required for not only stress response but also other biological responses in general.…”

Molecular Responses to Osmotic Stresses in Soybean

“…The pathway is related to various physiological processes and responses, ranging from floral development, senescence, pathogen defence, to abiotic stress responses (reviewed in (Zhou et al, 2010). Ubiquitin ligases are likely negative regulators in the osmotic stress response in higher plants, since loss-of-function Arabidopsis mutants are more droughttolerant while overexpressors are hypersensitive to drought stress (Cho et al, 2008).…”

“…GmRFP1 is up-regulated by ABA and salt stress, but down-regulated by drought and cold stress. The role of the ubiquitin-conjugating enzyme E2 (encoded by GmUBC2 that was identified from a salt-induced cDNA library) in soybean has been studied in more details (Zhou et al, 2010). GmUBC2 is an ubiquitin-conjugating enzyme homologous to the yeast RAD6.…”

“…GmUBC2 is an ubiquitin-conjugating enzyme homologous to the yeast RAD6. Ectopic expression of GmUBC2 confers tolerance to salt and drought stresses with the transgenic Arabidopsis plants, which exhibit higher superoxide dismutase (SOD) activity as well as proline and Na + content, when challenged with NaCl (Zhou et al, 2010) Post-transcriptional regulation by micro RNAs (miRNAs) miRNAs are short non-coding RNAs (18-24 nt) that inhibit gene expression through promoting mRNAs degradation or interfering translation after perfect or near perfect complementarily binding to their target mRNAs . The diversity, biogenesis, identification, and function of plant miRNAs were summarized previously (Yang et al, 2006;Zhang et al, 2006;Dong et al, 2008).…”