Constitutive expression of mustard annexin, AnnBj1 enhances abiotic stress tolerance and fiber quality in cotton under stress Kesanakurti Divya • S. K. Jami • P. B. Kirti Received: 18 September 2009 / Accepted: 30 January 2010 / Published online: 11 February 2010 Ó Springer Science+Business Media B.V. 2010 Abstract Annexins belong to a multigene family of Ca 2? dependent, phospholipid and cytoskeleton binding proteins. They have been shown to be upregulated under various stress conditions. We generated transgenic cotton plants expressing mustard annexin (AnnBj1), which showed enhanced tolerance towards different abiotic stress treat- ments like sodium chloride, mannitol, polyethylene glycol and hydrogen peroxide. The tolerance to these treatments was associated with decreased hydrogen peroxide levels and enhanced total peroxidase activity, enhanced content of osmoprotectants- proline and sucrose in transgenic plants. They showed higher retention of total chlorophyll and reduced TBARS in leaf disc assays with stress treat- ments, and decreased hydrogen peroxide accumulation in the stomatal guard cells when compared to their wild type counterparts. They also showed significantly enhanced fresh weight, relative water content, dry weight under stress. Treatment with sodium chloride resulted in enhanced expression of genes for D-pyrroline-5-carboxyl- ase synthetase in leaves, and sucrose phosphate synthase, sucrose synthase and cellulose synthase A in the leaves and fibers of transgenic plants. The transgenic plants main- tained normal seed development, fiber quality and cellulose content under stress. Keywords Transgenic cotton Á Mustard annexin Á Abiotic stress tolerance Á Proline accumulation Á Sucrose accumulation Introduction Annexins represent a multigene family of Ca 2? dependent phospholipid and cytoskeleton binding proteins in various plants, animals and fungi (Hofmann 2004). They were reported to possess phosphodiesterase activity, F-actin binding activity, peroxidase activity, calcium channel activity, and participate in Golgi-mediated secretion (Mortimer et al. 2008). Annexins might also participate in the regulation of callose and cellulose synthase activity (Hofmann 2004). The annexin gene expression seems to be regulated by various abiotic stress factors, such as abscisic acid (ABA), stress inducers-sodium chloride (NaCl), mannitol, and polyethylene glycol (PEG) in alfalfa cells (Kovacs et al. 1998), NaCl and drought in Arabidopsis seedlings (Cantero et al. 2006), salicylic acid (SA) in Arabidopsis (Gidrol et al. 1996), low temperature in wheat membranes (Breton et al. 2000), and mechanical stimulation in Bryonia (Tho- nat et al. 1997). The differential expression of some members of annexin gene family in mustard was observed in response to various signaling molecules, oxidative stresses and salinity (Jami et al. 2008). A Medicago trun- catula annexin (MtAnn1) was activated in roots in response to ‘nod’ factors elicited by Sinorhizobium meliloti (Neibel et al. 2002). Annexins of Medicago sativa and Arabidopsis thaliana have been implicated in oxidative stress response (Kovacs et al. 1998; Lee et al. 2004). In particular, an Arabidopsis annexin, AnnAt1 was able to rescue Escherichia coli Electronic supplementary material The online version of this article (doi:10.1007/s11103-010-9615-6) contains supplementary material, which is available to authorized users. K. Divya Á S. K. Jami Á P. B. Kirti (&) Department of Plant Sciences, University of Hyderabad, Hyderabad 500046, India e-mail: pbksl@uohyd.ernet.in 123 Plant Mol Biol (2010) 73:293–308 DOI 10.1007/s11103-010-9615-6