Effect of Brassinosteroid, Sodium Nitroprusside & Cadmium on Antioxidative Metabolism in Chickpea Seedlings

Chickpea (Cicer arietinum L.) is an annual grain leguminous crop that is mainly grown for human consumption throughout the world's population but its production is hampered by various types of biotic and abiotic stresses. Some heavy metals such as Zn, Cu and Cd are major constraints towards optimal growth of chickpea, as they affect many enzyme activities and expression of proteins. Toxicity could be caused due to the linking of these metals to sulphydryl groups (−SH groups) in proteins, as a result to which regulation of enzyme activities or distortion of enzymatic or protein structure occurs which causes deficiency effects (Van Assche and Clijsters, 1990). Cadmium is among the most toxic and hazardous pollutants in the biosphere. It induces oxidative stress in plants by liberating reactive oxygen species (ROS) like superoxide, alkoxy radical, hydrogen peroxide (H₂O₂) which causes oxidative damage in cellular macromolecules of plants. Brassinosteroids (BRs) are the natural polyhydroxy steroidal compounds promoting the plant growth (Bajguz, 2010). Apart from stimulation of growth, they have the potential to grant resistance to crops against environmental stresses (Beligni and Lamattina, 2000, Verma et al. 2014). Similarly, exogenous treatment of SNP (nitric oxide donor), can help in mitigating stress aroused due to herbicides, salt, and heavy metals. NO is known to modulate the participating enzymes of antioxidative defense metabolism or by directly scavenging ROS. Considering the importance of BR and NO, their role in providing protection against the harmful effects of Cd stress related to oxidative stress was studied in Chickpea Seedlings. Antioxidant enzyme activities were observed in the presence of Cd and in the combination of PGRs and Cd. It is concluded that NO donor and BRs may help in mitigating the negative impact of Cd stress by showing enhancement in the antioxidant enzymes activities.