Improvment of cold tolerance of chickpea through heavy polyamines catabolism and ethylene phytohormone

Abstract

Abstract Objective The current study was undertaken to investigate if there is a relationship between metabolism of ethylene and heavy polyamines (PAs) under cold stress in cold-tolerant and cold-sensitive chickpea (Cicer arietinum L.) genotypes. Materials and methods In this research, content of ethylene, heavy polyamines (spermidine (Spd) and spermine (Spm)), activities of PAs degradation pathway enzymes (polyamine oxidase (PAO) and diamine oxidase (DAO)), hydrogen peroxide (H2O2) and relative expression of 1-aminocyclopropane-1-carboxylic acid synthase (ACS) and 1-aminocyclopropane 1-carboxylic acid oxidase (ACO) genes in cold-tolerant (Sel 96th11439) and cold-sensitive (ILC 533) chickpea (Cicer arietinum L.) genotypes during the first and sixth days of cold stress at 4 °C compared to control condition as a factorial experiment in a Completely Randomized Design were investigated. Results During cold stress, both genotypes showed a significant increase in Spd and Spm content (66.66 and 96.23%). Ethylene production was declined in cold-sensitive genotype under cold stress compared to control conditions (up to 26.08%) while in the cold-tolerant genotype, the unique ethylene peak in early response (on the first day of stress) comared to control conditions (15.62%) was closely related to increased heavy polyamine accumulation. In the tolerant genotype, the increase in polyamine oxidase (PAO) and diamine oxidase (DAO) activity in early responses, (By 2.6- and 3.01-fold, respectively) was related to the increase in ethylene biosynthesis, as well as a concomitant increase in heavy polyamine (Spd & Spm) content by cold stress. In the tolerant genotype, the relative expression of ACS and ACO genes, after a significant increase on the first day of cold stress (5.2- and 4.03-fold, respectively), showed a significant decrease on the sixth day of the stress compared to the control plants, while a continuous decreasing trend (35-and 21.7-fold, respectively) was observed in the sensitive genotype compared to the control condition. Conclusions Findings of this research suggest that ethylene is intimately involved in improvement of cold stress tolerance through activation of a complex pathway of signalling by H2O2 that is polyamine catabolism-dependent.

Keywords

• ethylene metabolism
• hydrogen peroxide
• heavy polyamines
• cold stress
• chickpea