Changes in Antioxidant Enzyme Activity and Transcript Levels of Related Genes inLimonium sinenseKuntze Seedlings under NaCl Stress

Abstract

The halophyteLimonium sinenseKuntze is used in traditional Chinese medicine for clearing heat and for detoxification. To examine the detoxification and salt-tolerance mechanisms of this plant, we analyzed antioxidant enzyme activities and transcript levels of genes encoding antioxidant enzymes inL. sinenseseedlings under salt stress (500 mmol/L NaCl). Catalase showed the largest increase in activity, peaking on day 4 of the 7-day NaCl treatment. Peroxidase and superoxide dismutase activities also increased, peaking on days 2 and 3 of the NaCl treatment, respectively. The activities of antioxidant enzymes decreased as the duration of the NaCl treatment extended. The transcript levels of genes encoding antioxidant enzymes were upregulated under NaCl stress. The peak in theLsCATtranscript level was earlier than the peaks inLsAPXandLsGPXtranscript levels. The malondialdehyde content only slightly increased inL. sinenseseedlings under NaCl stress. This was indicative of a low level of lipid peroxidation, consistent with the increased antioxidant enzyme activities and gene transcript levels. These results show that, under NaCl stress, the antioxidant system ofL. sinenseis activated and effectively scavenges reactive oxygen species. This reduces oxidative damage and allows the plant to maintain growth under NaCl stress.

Exogenous Salicylic acid Ameliorates the Adverse Effects of Salt Stress on Antioxidant System in Rosmarinus officinalis L.

“…abiotic stress conditions has been reported in other plant species (Meyer et al, 2011). Zhang et al (2014) found that upregulation of transcript levels in CAT was consistent with the increase in CAT enzyme activity, suggesting that CAT might play a key role in scavenging excessive ROS in salinity and salicylic acid treated L. sinense. Furthermore, Sofo et al (2015) reported that increased CAT activity appears linked to lower oxidative damage, and gene expression regulation, was detected in plants with higher CAT activity, considering the protective function of this enzyme.…”

“…Results of gene expression analysis demonstrated a significant increase in the transcript levels of these three genes under saline stress and SA treatment as well. Since plants can activate antioxidative defense systems to protect themselves from oxidative stress induced by abiotic stresses such as salinity, analyses of the transcript levels of antioxidant defense genes may reflect the contributions of their products to salt stress response in plants (Lu et al, 2007;Carvalho et al, 2013 andZhang et al, 2014). Transcriptional analysis has the advantage of quantifying the changes in transcript levels of different genes.…”

“…Additionally, it has a negative impact on photosynthesis, water management and enzymatic activity (Salachna et al, 2017). It has been reported that salinity reduces plant productivity by reducing plant growth during the phase of osmotic stress and subsequently by inducing leaf senescence during the phase of toxicity after excessive salt accumulation in oxidative damage of lipids, proteins, and nucleic acids (Abbaspour, 2012 andAbdul Qados, 2015), resulting in the formation of reactive oxygen species(ROS) (Sudhir & Murthy, 2004;Nazar et al, 2011;He et al, 2014 andLi et al, 2014). To mitigate the harmful effects of these ROS, plants have improved an effective scavenging system composed of non-enzymatic antioxidants (carotenoids, ascorbate, and tocopherol) and enzymatic antioxidants, such as catalase (CAT) and peroxidase (POD) (Li et al, 2014).…”

Improvement of cold stress resistance via free radical scavenging ability and promoted water status and photosynthetic capacity of gallic acid in soybean leaves

“…As observed by Ogweno et al (2008) Exposure to low temperature may result in the increased generation of ROS in plants (Zhang et al, 2014). It is well known that exposure of soybean leaves to cold stress resulted the toxic H 2 O 2 levels that occurred to the diminished activity of , CAT and POX.…”

“…When stress cause loss of CAT activity, the activities of the Halliwell-Asada pathway enzymes such as APX and GR induces (Zhang et al, 2014). As compatible to this expression, the lower cold stress caused an increase in APX and GR activity in soybean.…”