Ethylene evolution and antioxidant defence mechanism in Cicer arietinum roots in the presence of nitrate and aminoethoxyvinylglycine

• Published in: Plant physiology and biochemistry 2000-09, Vol.38 (9), p.709-715
• Main Authors: Singh Nandwal, Ajit, Maan, Anita, Singh Kundu, Baljeet, Sheokand, Sunita, Vrat Kamboj, Dev, Sheoran, Anita, Kumar, Bhumesh, Dutta, Divya
• Format: Article
• Language: English
• Subjects: aminoethoxyvinylglycine; antioxidants; Biological and medical sciences; Cicer arietinum; ethylene; Fundamental and applied biological sciences. Psychology; Growth regulators; membrane integrity; Metabolism; nitrate; Physiological diseases. Varia; Phytopathology. Animal pests. Plant and forest protection; Plant physiology and development
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/S0981-9428(00)01174-8

The plants of chickpea ( Cicer arietinum L.) cv. HC-1 were raised in earthen pots filled with 5 kg washed river sand under natural conditions of the screen house. Forty to forty-five days after sowing, the roots were exposed to 10, 20 and 40 mM NO 3 – through rooting medium with the aim for studying NO 3 – induced changes in ethylene production and root functioning. Aminoethoxyvinylglycine (AVG, 5 μM), an ethylene biosynthesis inhibitor, was added after 24 h of NO 3 – treatments. Three days after the treatments, NO 3 – applied at 10 mM induced a significant increase in 1-amino cyclopropane-1-carboxylic acid (ACC) content (49 %) and in vivo ACC oxidase activity (100 %) which were associated with an increase in ethylene production (25 %) and with an important increase in both H 2O 2 (60 %) and malondialdehyde (MDA, 1 270 %). In contrast, supply of NO 3 – at 40 mM resulted in an important increase in ethylene production (400 %) by inducing significant enhancement of ACC content (123 %), ACC oxidase activity (128 %) and with simultaneous increase of H 2O 2 (160 %) and MDA (1 900 %). The reversible membrane alteration showed a linear correlation with ethylene production. This was confirmed by a sharp decline in NO 3 – induced ethylene evolution by AVG. An oxidative damage by NO 3 – to the defence mechanism was evident from the increase in H 2O 2 content which is apparent from the decrease in activities of superoxide dismutase (EC 1.15.1.1), catalase (EC 1.11.1.6), ascorbate peroxidase (EC 1.11.1.11) and glutathione reductase (EC 1.11.1.9) to 23–67, 39–43, 33–55 and 26–45 %, respectively. The AVG treatment showed partial recovery in the activities of these enzymes and decrease in H 2O 2 content (17–32 %). It is inferred that ethylene evolution due to NO 3 – is the key marker interfering with the functioning of roots along with the weakening of antioxidant defence mechanism.