Plant Archives Volume 20 No. 2, 2020 pp. 3510-3514 e-ISSN:2581-6063 (online), ISSN:0972-5210 PROLINE ACCUMULATION IN THE LEAVES OF FOUR POTATO CULTIVARS IN RESPONSE TO WATER STRESS Subhash Kumar 1 *, Devendra Kumar 2 , Pushpendra Kumar 3 , Punjab Singh Malik 4 * and Mahesh Kumar 2 1* Department of Botany,C.C.R. (PG) College, Muzaffarnagar, (U.P.), India. 2 ICAR-Central Potato Research Institute, Campus Modipuram, Meerut, (U.P.), India. 3 Department of Biotechnology, College of Agriculture, SVBPUAT, Meerut, (U.P.), India. 4* Department of Botany, Meerut College, Meerut, (U.P.), India. Abstract Influence of water stress on four potato cultivars (i.e. Kufri Chipsona-1, Kufri Pukhraj, Kufri Lauvkar and Desiree) was investigated with respect to three growth stages (i.e tuber initiation stage (T 2 ), tuber enlargement stage (T 3 ) and tuber maturation stage (T 4 ). In present study proline accumulation was found to be increased in potato leaves due to water stress at different growth stages. Much increase in proline content was found when water stress was imposed at tuber initiation stage (>75%) and at tuber enlargement stage (>85%) in comparison with well irrigated control T 1 . Accumulation of proline may be ascribed as due to three metabolic causes i.e. de novo synthesis from glutamate, lower rate of proline catabolism because of inhibition activities of proline dehydrogenase and proline oxidase by water stress and slow incorporation of proline into protein. The cultivar Kufri Lauvkar recorded accumulation of maximum proline content due to water stress treatments T 2 , T 3 and T 4 in comparison with well watered control T 1 . Among growth stages, Kufri Lauvkar showed highest proline elevation (> two folds) when stress was given at tuber maturation stage. Kufri Chipsona-1 recorded minimum proline content as a result of all water stress treatments except T 3 where this cultivar was found second to lowest in proline accumulation during both the years during this study. Key words: Proline, water stress, potato, tuber initiation, tuber enlargement, tuber maturation stage Introduction In the era of global climate change, sustainability of crop production is a serious challenging issue due to increasing incidences of both biotic and abiotic stresses in farmer’s field (Muhammad Nadeem et al., 2019). Enhancing water stress tolerance in plants through conventional breeding is a useful approach and a principal strategy for crop improvement (Farooq et al., 2014). In mesophytic plants, proline accumulation has been reported as one of the marked responses to water stress by several authors (Keshav Dahal et al., 2019, Paleg and Aspinall, 1981; Hanson and Hitz, 1982; Rhodes and Handa, 1989; Losch, 1991; Galiba, 1994). During water stress, proline plays an important role and act as a signaling compound to regulate mitochondria function and affect cell proliferation by means of activating particular genes, which are essential for stress recovery (Solanki et al., 2015). Proline accumulation aids in retaining membrane integrity by decreasing oxidation of lipids through guarding cellular redox potential and scavenging free radicals (Shinde et al., 2016). Proline accumulation is favoured by high leaf carbohydrate status and also by illumination (Hanson and Hitz, 1982). Naidu et al., (1990) showed that a progressive water stress rather than a rapid water stress resulted in proline being the dominant accumulated compound. Accumulation of proline may be ascribed as due to three metabolic causes of which de novo synthesis from glutamate is considered to be the major factor (Hanson and Hitz, 1982; Venekamp et al., 1989), other factors are lowered rate of proline catabolism because of inhibition of activities of proline dehydrogenase and proline oxidase by water stress (Venekamp et al., 1989) and slower incorporation of proline into protein (Hanson and Hitz, 1982). Physiological significance of proline *Author for correspondence : E-mail : punjabmalik@gmail.com, subhashvikal2012@gmail.com