Cold stress, which causes dehydration damage to the plant cell, is one of the most common abiotic stresses that adversely affect plant growth and crop productivity. To improve its cold-tolerance, plants often enhance expression of some cold-related genes. In this study, a cold-regulated gene encoding 25 KDa of protein was isolated from Brassica napus cDNA library using a macroarray analysis, and is consequently designated as BnCOR25. RT-PCR analysis demonstrated that BnCOR25 was expressed at high levels in hypocotyls, cotyledons, stems, and flowers, but its mRNA was found at low levels in roots and leaves. Northern blot analysis revealed that BnCOR25 transcripts were significantly induced by cold and osmotic stress treatment. The data also showed that BnCOR25 gene expression is mediated by ABA-dependent pathway. Overexpression of BnCOR25 in yeast (Schizosaccharomyces pombe) significantly enhanced the cell survival probability under cold stress, and overexpression of BnCOR25 in Arabidopsis enhances plant tolerance to cold stress. These results suggested that the BnCOR25 gene may play an important role in conferring freezing/cold tolerance in plants.
" Toyobo , Osaka , Japan ) was applied in the detection system . Real - time PCR reaction was performed using the Real - time PCR Master Mix ( Toyobo ) according to the manual . The Actin gene was used as an internal control to normalize the data . Relative quantity of the target gene expression level was performed using the comparative Ct method ( Chen et al . , 2011 ) . For crude anti - oxidative enzyme extraction , 0 . 3 g of fresh leaves were ground to a fine powder in liquid nitrogen and then mixed with 4 mL sodium phosphate buffer ( 150 mM , pH 7 . 0 ) and treated with pre - cooling at 4 °C . The homogenate was transferred into a 10 - mL centrifuge tube and then centrifuged for 20 min with 13 ,"
"In plant cells, extracellular freezing damages membrane systems . This damage is largely due to the acute dehydration associated with freezing (Mahajan and Tuteja 2005; Chen et al. 2011). Reactive oxygen species (ROS) that are produced in response to cold stress may contribute to membrane damage. "
[Show abstract][Hide abstract] ABSTRACT: Antarctica is one of the most extreme environments on Earth. Deschampsia antarctica Desv. is the only monocot vascular plant that colonizes the Antarctic Peninsula. The survival of this species in this harsh environment suggests that this plant possesses genes associated with cold and UV tolerance. Using suppression subtractive hybridization, we identified a total of 112 differentially expressed genes under cold and UV irradiance conditions. Northern blot analysis and real-time RT-PCR confirmed expression differences among several genes. Using similarity search analysis, we identified a number of genes that have not been previously reported. The results showed that cold and UV radiation mainly induce the expression of genes related to transcription, energy and defense response. Interestingly, part of the isolated genes corresponds to unknown or hypothetical proteins. This set of tolerance-related genes could be relevant to uncover the mechanisms by which this extremophile survives in its environment and contribute to the development of biotechnology in Antarctic species.
"For example, expression of CbCOR15 from C. bungeana was detected only in leaves after 1 day of treatment at 2 • C, but not in roots (Si et al., 2009). BnCOR25 from B. napus transcription level significantly increased in roots after 3 h cold treatment at 4 • C, and declined to low level after 6 h cold treatment and enhanced again after 12 h cold treatment (Chen et al., 2011). Different expression patterns may indicate different roles of these COR genes in each species. "
[Show abstract][Hide abstract] ABSTRACT: Low temperature is among the most significant abiotic stresses, restricting the habitats of sessile plants and reducing crop productivity. Cold regulated (COR) genes are low temperature-responsive genes expressing under regulation of a specific signal transduction pathway, which is designated C-repeat-binding-factor (CBF) signaling pathway. In the present article, cold bioassay showed that the transcript level of cold regulated gene CbCOR15b from shepherd's purse (Capsella bursa-pastoris) was obviously elevated under cold treatments. Reverse transcription-PCR (RT-PCR) and GUS report system revealed that unlike AtCOR15b, CbCOR15b expressed not only in leaves but also in stems and maturation zone of roots. When transgenic tobacco plants ectopically expressing CbCOR15b were exposed to chilling and freezing temperatures, they displayed more cold tolerance compared to control plants. According to the electrolyte leakage, the relative water content, the glucose content and the phenotype observation, CbCOR15b transformants suffered less damage under cold stress. Further investigation of the subcellular localization of CbCOR15b by transient expression of fusion protein CbCOR15b-GFP revealed that it was localized exclusively in the chloroplasts of tobacco mesophyll cells and in the cytoplasm of onion epidermal cells. It can be concluded that CbCOR15b which located in the chloroplasts and in the cytoplasm of cells without chloroplasts was involved in cold response of C. bursa-pastoris and conferred enhanced cold tolerance in transgenic tobacco plants.
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