Response of antioxidant enzymes in rice (Oryza sauva L. cv. Dongjin) under mercury stress

Abstract

We studied the effects of different co~[et~bral~ns of mercury (0.0 to 100 !~t) o. growth and p~Uc efficiency in rice plants treated for 21 d. In addilJo., we invesl~ated how this metal affected Ihe malondtaidehy~ (MDA) content as well as lhe ~ of five ~ enzymes -superoxJde dimnutase (SOD), ascorbale peroxidase (APX), glutathione reductase (GR), guaiacol pemxidase (POD), and ratalase (CAT). ~c ef@~mcy (F,/Fm) and seedling growth decreased as the cancentrabon of H s was increased in the growth media. Plants also responded to Hg-induced oxidaslbress by charting the levels of their antioxiclat~ enzymes. Enhanced lipid peroxidabon was observed in both leaves and roots that had been exposed to oxldal@e m, with leaves showing higher enzymatic acth~. Both SOD and APX acti@l~s increased in beabnents with up to 50 pM I~, then decreased at higher concentrations. In the leaves, bolh CAT and POD acth~es increased ~radually, with CAT levels decreasing at h~her concentratJon~ In the roots, hm~mver, CAT aclivity remained Ui~-hansed while that of POD increased a bit more than did the control for concen~alJons of up to 10 pM H& At higher Hg levels, beth CAT and POD activities decreased. GR act~ increased in leaves exposed to no more than 0.25 pM Hg, then decreased gradually. In contrast, its activity was greatly inhibited in the roots. Based on these results, we surest that when rice plants are exposed to different concentrations of mercury, their anlJoxidative enzymes become involved in defense mechanisms against the free radicals that are induced by this stress.

Effects of NaCl stress on germination, antioxidant responses, and proline content in two rice cultivars

“…AOS include superoxide anion (02), the hydroxyl radical ( 9 OH), hydrogen peroxide (H202), and singlet oxygen (102). *Corresponding author; fax +82-55-758-5110 e-mail jjl@gshp.gsnu.ac.kr The increase in AOS, which are also produced during normal aerobic metabolism, seems to occur in response to all abiotic stresses, including chilling (Lee et al, 2004), heavy metal toxicity (Ali et al, 2002), drought (Smirnoff, 1993), and salt Gossett et al, 1996). Failure to quench or inactivate the AOS may lead to the degradation of macromolecules in cells as membrane lipids, proteins, and DNA (EIstner, 1982;Smirnoff, 1993).…”

Ethylene-insensitive mutants of Nicotiana tabacum exhibit drought stress resistance

“…The measurement of MDA (Shi et al 2012a), the accumulation of soluble sugar and proline (Bates et al 1973;Chinard 1952;Watanabe et al 2000), and the activities of SOD and POD (Ali et al 2002) were as previously described.…”

Assessing the difference of tolerance and phytoremediation potential in mercury contaminated soil of a non-food energy crop, Helianthus tuberosus L. (Jerusalem artichoke)

“…As mercury is a toxic metal, many studies have shown that, especially in the form of Hg 2+ , it readily accumulates in plant roots, though there is a barrier to translocation from roots to shoots, and that it has high phytotoxicity compared with other heavy metals ( Munzuroglu & Geckil, 2002 ; Gautam et al, 2010 ). The phytotoxic effects of mercury include the following: reduction in plant growth and yield production, alterations in nutrient uptake and homeostasis, genotoxicity on genomic DNA molecule, elevated amounts of reactive oxygen species and membrane lipid peroxidation, changes in the integrity of bio-membranes, inhibition of plant photosynthesis, and perturbation of almost any function in which critical or non-protected proteins are involved due to mercury’s high affinity for sulphydryl groups ( Patra & Sharma, 2000 ; Ali, Chun & Lee, 2002 ; Patra et al, 2004 ; Israr et al, 2006 ; Eibaz et al, 2010 ; Malar et al, 2015a ; Malar et al, 2015b ; Wang et al, 2015a ).…”