Molecular cloning and characterization of wheat calreticulin (CRT) gene involved in drought-stressed responses.
Calreticulin (CRT) is a highly conserved and ubiquitously expressed Ca(2+)-binding protein in multicellular eukaryotes. CRT plays a crucial role in many cellular processes including Ca(2+) storage and release, protein synthesis, and molecular chaperone activity. To elucidate the function of CRTs in plant responses against drought, a main abiotic stress limiting cereal crop production worldwide, a full-length cDNA encoding calreticulin protein namely TaCRT was isolated from wheat (Triticum aestivum L.). The deduced amino acid sequence of TaCRT shares high homology with other plant CRTs. Phylogenetic analysis indicates that TaCRT cDNA clone encodes a wheat CRT3 isoform. Southern analysis suggests that the wheat genome contains three copies of TaCRT. Subcellular locations of TaCRT were the cytoplasm and nucleus, evidenced by transient expression of GFP fused with TaCRT in onion epidermal cells. Enhanced accumulation of TaCRT transcript was observed in wheat seedlings in response to PEG-induced drought stress. To investigate further whether TaCRT is involved in the drought-stress response, transgenic plants were constructed. Compared to the wild-type and GFP-expressing plants, TaCRT-overexpressing tobacco (Nicotiana benthamiana) plants grew better and exhibited less wilt under the drought stress. Moreover, TaCRT-overexpressing plants exhibited enhanced drought resistance to water deficit, as shown by their capacity to maintain higher WUE (water use efficiency), WRA (water retention ability), RWC (relative water content), and lower MDR (membrane damaging ratio) (P < or = 0.01) under water-stress conditions. In conclusion, a cDNA clone encoding wheat CRT was successfully isolated and the results suggest that TaCRT is involved in the plant response to drought stress, indicating a potential in the transgenic improvements of plant water-stress.
Jia
Xiao-Yun
XY
The National Key Facility for Crop Gene Resources and Genetic Improvement, Key Laboratory of Crop Germplasm and Biotechnology, Ministry of Agriculture, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Xu
Chong-Yi
CY
Jing
Rui-Lian
RL
Li
Run-Zhi
RZ
Mao
Xin-Guo
XG
Wang
Ji-Ping
JP
Chang
Xiao-Ping
XP
D000595:Amino Acid Sequence; D037282:Calreticulin / Q000235:genetics* / Q000378:metabolism*; D003001:Cloning, Molecular; D003890:Desiccation; D004190:Disasters; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018745:Genome, Plant; D008969:Molecular Sequence Data; D010802:Phylogeny; D018517:Plant Roots / Q000166:cytology; D011092:Polyethylene Glycols / Q000494:pharmacology; D014908:Triticum / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D014867:Water / Q000378:metabolism*
D037282:Calreticulin; D014867:Water; D011092:Polyethylene Glycols