Journal of Plant Physiology 164 (2007) 1367—1376 Stress-induced synthesis of proline confers tolerance to water deficit in transgenic wheat Eliane Cristina Gruszka Vendruscolo a,à , Ivan Schuster b , Marcos Pileggi c , Carlos Alberto Scapim d , Hugo Bruno Correa Molinari e , Celso Jamil Marur e , Luiz Gonzaga Esteves Vieira e a Universidade Federal do Parana´-Campus Palotina, Rua Pioneiro, 2153, CEP 85950-000 Palotina-Pr, Brazil b Coodetec-Cooperativa Central de Pesquisa Agrı ´cola, CEP 85813-450 Cascavel-Pr, Brazil c Universidade Estadual de Ponta Grossa, Debiogem, CEP 84030-900 Ponta Grossa-Pr, Brazil d Universidade Estadual de Maringa´, PGM-Agra´rias, CEP 87020-900 Maringa´-Pr, Brazil e Instituto Agrono ˆmico do Parana´, CEP 86047-902 Londrina-Pr, Brazil Received 7 February 2007; received in revised form 9 May 2007; accepted 9 May 2007 KEYWORDS Drought tolerance; P5CS; Proline; Wheat; Transformation Summary Water deficit is one of the main abiotic factors that affect spring wheat planted in subtropical regions. Accumulation of proline appears to be a promising approach to maintain the productivity of plants under stress condition. However, morphological alterations and growth reduction are observed in transgenic plants carrying genes coding for osmoprotectants controlled by constitutive promoters. We report here the effects of water deficit on wheat plants transformed with the Vigna aconitifolia D 1 -pyrroline-5-carboxylate synthetase (P5CS) cDNA that encodes the key regulatory enzyme in proline biosynthesis, under the control of a stress-induced promoter complex—AIPC. Transgenic wheat plants submitted to 15 days of water shortage presented a distinct response. We have found that drought resulted in the accumulation of proline. The tolerance to water deficit observed in transgenic plants was mainly due to protection mechanisms against oxidative stress and not caused by osmotic adjustment. & 2007 Elsevier GmbH. All rights reserved. Introduction Water deficit is one of the main abiotic factors affecting spring wheat yields in subtropical lati- tudes. There has been considerable work in stress-tolerant wheat improvement using classical ARTICLE IN PRESS www.elsevier.de/jplph 0176-1617/$ - see front matter & 2007 Elsevier GmbH. All rights reserved. doi:10.1016/j.jplph.2007.05.001 Abbreviations: 2, 4-D, 2,4-dichlophenoxyacetic acid; AIPC, ABA-inducible promoter complex; PAT, phosphinothricin acetyl- transferase; GUS, b-glucuronidase; MDA, malondialdehyde; MPa, megapascal; MS, Murashige and Skoog; MSI, membrane stability index; P5CS, D 1 -pyrroline-5-carboxylate synthetase; PCR, poly- merase chain reaction; PPT, phosphinothricin à Corresponding author. Tel.: +554436493444 R209; fax: +55 4436496616. E-mail address: vendruscolo@ufpr.br (E.C.G. Vendruscolo).