ORIGINAL PAPER Effects of exogenous abscisic acid on some physiological responses in a popular aromatic indica rice compared with those from two traditional non-aromatic indica rice cultivars Aryadeep Roychoudhury Æ Supratim Basu Æ Dibyendu N. Sengupta Received: 9 September 2008 / Revised: 27 February 2009 / Accepted: 7 March 2009 / Published online: 28 March 2009 Ó Franciszek Go ´rski Institute of Plant Physiology, Polish Academy of Sciences, Krako ´w 2009 Abstract The poor productivity and local confinement of indigenous aromatic rice varieties are mostly due to their susceptibility to salinity/drought/abscisic acid (ABA)- mediated abiotic stresses. It is thus essential to study the effects of several stress factors on their physiological parameters so as to improve their tolerance mechanism and enhance their global demand. Previously, we studied the effect of salinity stress on the physiological and molecular responses of the common aromatic rice Gobindobhog. The objective of this study was to understand the influence of exogenous ABA on some biochemical parameters in Gobindobhog, and comparison with those from non-aro- matic M-1-48 and Nonabokra rice. The highest endogenous hydrogen peroxide content and membrane lipid peroxida- tion (increased malondialdehyde and lipoxygenase activity) were found in ABA-treated Gobindobhog leaves. While the catalase activity was down regulated the most in ABA-treated Gobindobhog leaves, the guaiacol peroxidase activity was induced maximally, indicating the protective role of peroxidase rather than catalase, during ABA- induced oxidative damages. The antioxidant, anthocyanin, showed the highest level in ABA-treated Nonabokra. Enhanced cysteine, following ABA exposure and the highest levels of reducing sugars, total amino acids, pro- line, and polyamines (putrescine and spermidine) recorded in Gobindobhog, probably served to shield from ABA- induced stress injuries, whereas the spermine levels were comparable in ABA-treated Nonabokra and Gobindobhog. The aroma content, intensified after ABA treatment, was markedly noted in Gobindobhog. Thus, the systematic examination of ABA-mediated stress revealed the most prominent oxidative damages in Gobindobhog, even higher than M-1-48, with a concomitant enhancement in peroxi- dase system and particularly osmolyte or polyamine levels to ensure its sustenance. Keywords Abscisic acid Á Antioxidants Á Aromatic rice Á Lipid peroxidation Á Osmolytes Á Polyamines Introduction The phytohormone ABA has been shown to mediate many physiological and developmental processes throughout the life cycle of plants including responses of plants to envi- ronmental stresses such as high osmoticum, high salinity, drought, and low temperature/freezing (Nambara et al. 1998). Under drought, cold or salt stress conditions, plants accumulate increased amounts of ABA, which plays a critical role in the regulation of plant water balance and osmotic stress tolerance. All these processes are mostly associated with stomatal closure, thus conserving excess water loss due to transpiration (Finkelstein et al. 2002). Circumstantial evidence indicates that one model of ABA action may be related to the oxidative stress in plant cells. ABA can cause the increase of lipid peroxidation expressed as malondialdehyde (MDA) produced in plant cells (Bueno et al. 1998). ABA also may lead to an increased generation Communicated by M. Horbowicz. A. Roychoudhury Á S. Basu Á D. N. Sengupta Department of Botany, Bose Institute, 93/1, Acharya Prafulla Chandra Road, Kolkata 700 009, West Bengal, India Present Address: A. Roychoudhury (&) Plant Molecular Biology and Biotechnology Laboratory, Department of Botany, University of Calcutta, 35, Ballygunge Circular Road, Kolkata 700 019, West Bengal, India e-mail: aryadeep19@rediffmail.com 123 Acta Physiol Plant (2009) 31:915–926 DOI 10.1007/s11738-009-0305-4