American Journal of Plant Sciences, 2013, 4, 817-823 doi:10.4236/ajps.2013.44100 Published Online April 2013 (http://www.scirp.org/journal/ajps) 817 Effect of Jasmonic Acid on Photosynthetic Pigments and Stress Markers in Cajanus cajan (L.) Millsp. Seedlings under Copper Stress Sharma Poonam, Harpreet Kaur, Sirhindi Geetika * Department of Botany, Punjabi University, Patiala, India. Email: * geetikasir123@gmail.com Received February 22 nd , 2013; revised March 25 th , 2013; accepted April 2 nd , 2013 Copyright © 2013 Sharma Poonam, Sirhindi Geetika. This is an open access article distributed under the Creative Commons Attribu- tion License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ABSTRACT Jasmonates are class of plant growth regulators act as signal molecule that intercede various components in physiologi- cal and metabolic regulation, stress responses and possibly communication through signal transduction. Oxidative stress due to heavy metal exposure stimulates synthesis and activity of antioxidant metabolites and enhances antioxidant en- zyme activities that could protect plant tissues. The aim of this study was to investigate the exogenous effect of JA at seed level which can transduce throughout seedling growth and regulate antioxidant activities such as superoxide dis- mutase (SOD; EC 1.15.1.1) and guaiacol peroxidase (POD; EC 1.11.1.7) in 12 days old seedlings of pigeon pea (Ca- janus cajan (L.) Millsp.) in presence and/or absence of copper. The activity of SOD and POD increased significantly in presence of Cu 2+ after seed priming with JA. JA also helps in chlorophyll and carotenoid accumulation and neutralizes the toxic effect of Cu 2+ on seedlings. This is the first report of JA effect on photosynthetic pigment accumulation and H 2 O 2 mitigating enzymes i.e. SOD and POD and it could be recommended that seed priming with JA help in amelio- rating toxic effect of Cu 2+ . Keywords: Jasmonic Acid; Copper Sulphate; Lipid Peroxidation; Superoxide Dismutase; Guaiacol Peroxidase; Total Chlorophyll; Carotenoids 1. Introduction Jasmonic acid is a member of plant growth regulators named jasmonates occurring ubiquitously in plants which exhibit hormone like properties, regulating various phy- siological processes related to plant growth and devel- opment, promotion of leaf senescence estimated by de- crease in chlorophyll content and depression of photo- synthesis related gene which was one of the first reported physiological effects of jasmonates group [1]. But these consequences are based mainly on the studies done on excised or intact differentiated leaves after exogenous application of jasmonates [2]. Till now it is considered that jasmonates particularly methyl esters of JA (Me-JA) as a chemical stress agent mimicking the effect of that appear in response to external stress factors inducing senescence [3]. Me-JA preferentially inhibited chloro- phyll accumulation at the level of chlorophyll precursors in the dark as compared to other inhibitory growth regu- lators as chemicals [4] under different environmental conditions. Heavy metal is one of the common stress, plants have from their habitat without any option. Accumulation of heavy metals in plants when passes the threshold level, resulted to toxicity in plants lead to many morphological and physiological changes [5]. Copper is a heavy metal which is an essential ion for various proteins which are structural and functional part of vital machinery of plant cell. The requirement of Cu 2+ ion by the plant is very low, as core component of photosynthetic pigments and as antioxidant enzymes such as SOD. Unfortunately, plants find an ample supply of copper through their roots from soil and accumulated in system causing stress [6] along with triggering of certain physiological responses [7]. Cajanus cajan (L.) Millsp. (pigeonpea) is an important pulse crop of the world which is rich in protein. Pigeon- pea is major food legume of India and has great area un- * Corresponding author. Copyright © 2013 SciRes. AJPS