Evaluation of polyamine biosynthetic pathway in chickpea plants under cold stress

ontribution of polyamines (PAs) in response to cold stress (4◦C) were studied in chickpea (Cicer arietinum L.) genotypes. The content of putrescine (Put), spermidine (Spd), Spermine (Spd), hydrogen peroxide (H2O2) and relative expression of Arginine decarboxylase (ADC) and ornithine decarboxylase (ODC) genes that involve in Put biosynthesis pathway were investigated in cold-tolerant (Sel96th 11439) and cold-sensitive (ILC533) genotypes. In the tolerant genotype, H2O2 accumulation was gradually decreased (up to 4.7%) from the first day to 6th day of cold stress treatment and its accumulation decreased while its accumulation in sensitive genotype increased up to 50% compared to the control. Under cold stress, as damage index (H2O2) was decresed, PA and Put content increased comparing to control conditions (up to 116%), while Put content in cold-sensitive genotype was lower compared to cold-tolerant genotype on the sixth day (up to 14%). Therefore, Put accumulates as an osmoprotectant in response to induced damage caused by cold stress. Under cold stress, increasing in Put content was accompanied by increasing of Spd and Spm comparing to control conditions (up to 66% and 69%) while, their increases in cold-tolerant genotype was more than cold-sensitive one. Also in both genotypes, under cold stress the transcript levels of ADC gene was increased up to 26-fold and the transcripts of ODC gene was increased up to 2-fold comparing to control conditions. These results showed that in chickpea under cold stress, increase of Put biosynthesis dependent on ADC pathway was dominant compared to ODC gene. Possibly increasing relative expression of the ADC gene with the production of Put improved cold tolerance mechanisim. Therefor, increasing PAs content particularly Put which is probably synthesized by the up-regulation of ADC gene, plays an important role in cold tolerance development in chickpea.