Plant & Animal Genomes XVII Conference

January 10-14, 2009
Town & Country Convention Center
San Diego, CA

Cloning And Expression Analysis Of An Arginine Decarboxylase Gene (PtADC) From Poncirus trifoliata Under Abiotic Stresses

Liu Ji-Hong , Wang Jing , Deng Xiu-Xin

  National Key Laboratory of Crop Genetic Improvement, National Center of Crop Molecular Breeding, Huazhong Agricultural University, Wuhan 430070, China

Poncirus trifoliata is a very cold hardy species, which is the most important rootstock in citrus Industry. It has to be pointed that although it is clear that P. trifoliata is tolerant to low temperature the mechanism underlying such physiological process remains to be elusive. Polyamiens are polycationic low molecular weight molecules that play key role in stress tolerance. In order to elucidate the possible correlation between polyamines and the cold hardinesss of this uniqe germplasm attempts were made to clone key gene responsible for polyamine biosynthesis. To this end, a gene encoding arginine decarboxylase (PtADC) was isolated, which is 2256 bp long, encoding an ORF of 751 amino acids with a predicted molecular weight 80.53KD and isoelectric point of 5.14. It shared high sequence similarity with those from other plants at either amino acid or nucleotide level. Southern blotting analysis showed that only one copy of ADC in P. trifoliata genome. Expression of PtADC was induced quickly by low temperature, salt. Overexpression of PtADC in citrus led to accumulation of putrescine. Examination of stress tolerance of the transgenic citrus plants is in progress. In addition, it has been transformed into an Arabidopsis thatliana mutant (ADC1-1) to decipher its function. Meanwhile, efforts are made to ectopically expres the gene in tobacco and tomato to illustrate its role in stress tolerance.