ORIGINAL ARTICLE Alternate mild drought stress (20.1 MPa PEG) immunizes sensitive chickpea cultivar against lethal chilling by accentuating the defense mechanisms Simranjeet Kaur 1 • Ankur Jairath 1 • Inderjeet Singh 2 • Harsh Nayyar 3 • Sanjeev Kumar 1 Received: 28 November 2015 / Revised: 23 March 2016 / Accepted: 5 July 2016 Ó Franciszek Go ´rski Institute of Plant Physiology, Polish Academy of Sciences, Krako ´w 2016 Abstract The changes in climate particularly, the rise in temperature and humidity affect the physiological func- tions of plants subsequently affecting crop productivity adversely. A strategy is required which can be directly implemented in fields to induce the tolerance in crop plants. In present study, two chickpea varieties with con- trasting sensitivity PDG3 (Tolerant) and GPF2 (Sensitive) were raised hydroponically, preconditioned with mild drought stress (0.1 MPa PEG-6000) for 3 days (above 0.1 MPa is lethal) and subsequently recovered for double time (6 days) and finally exposed to lethal cold stress (4 °C) for 3 days. We hypothesize that preconditioning with non-lethal drought stress may immunize the plants to combat lethal cold stress. Membrane integrity improved in root and shoot, lipid peroxidation decreased to control level in preconditioned seedlings. Cellular respiration ability (% TTC reduction) increased in the preconditioned seedlings to almost 90 % in the shoot and 60 % in the root, con- currently it was 45 % in non-preconditioned seedlings. Proline content also increased in preconditioned seedlings, especially roots. Carbohydrate had a shift in terms of a high amount of total, reducing sugars and starch in non-pre- conditioned seedlings compared to preconditioned. Both PDG3 and GPF2 showed enhanced SOD, CAT and GPOX activity indicating tolerance against cold-induced oxidative stress and preconditioning induced improvement against lethal cold stress. Keywords Preconditioning Á Cold stress Á Lethal Á Electrolyte leakage Á Lipid peroxidation Á Cryoprotectant Introduction In nature, plants do not always live in their most hostile environment; they are exposed to various biotic and abiotic factors and forced either to adapt to these conditions or perish. There is huge demand for research into the cellular and molecular mechanisms of plant stress responses as understanding these mechanisms can help to improve crop growth in response to global environmental changes (Anand and Gill 2015; Mittler 2006). Chickpea (Cicer arietinum L.) is the third most important crop in the world after common bean (Phaseolus vulgaris L.) and field pea (Pisum sativum L.). India contributes ca. 70 % of worlds’ production. The chief restrictions in chickpea production are biotic stresses like Ascochyta blight, Fusarium wilt, pod borer, and abiotic stresses such as drought, heat, cold and high-salinity. Global annual production losses due to abiotic stresses alone are estimated to be around 3.7 million tons (mt), which amounts to 40–60 % average loss (Singh 1997; Varshney et al. 2009). In fact, the estimated com- munal yield losses due to abiotic stresses are significantly higher (6.4 mt) than for biotic stresses (4.8 mt) (Ryan 1997; Varshney et al. 2009). Chickpea fulfills a noticeable nutritional requirement of population in developing coun- tries as it is a rich source of carbohydrates (40–59 %), proteins (13.5–31.7 %), vitamins, minerals, etc. This crop Communicated by J Gao. & Sanjeev Kumar sanjeevpuchd@gmail.com; sanjeevcbs@cup.ac.in 1 Centre for Biosciences, School of Basic and Applied Sciences, Central University of Punjab, Bathinda, Punjab, India 2 Department of Plant Breeding and Genetics, PAU, Ludhiana, Punjab, India 3 Department of Botany, Panjab University, Chandigarh, India 123 Acta Physiol Plant (2016) 38:189 DOI 10.1007/s11738-016-2212-9