Journal Name: Frontiers in Plant Science    ISSN: 1664-462X
Article type: Original Research Article     Received on: 21 Aug 2014
Accepted on: 18 Dec 2014        Provisional PDF published on: 18 Dec 2014

Hui-Juan Gao^1&, Hong-Yu Yang^1&, Jiang-Ping Bai¹, Xin-Yue Liang², Yan Lou¹,  Jun-Lian Zhang¹, Di Wang1^*, Jin-Lin Zhang^3*, Shu-Qi Niu³, Ying-Long Chen⁴ 

¹ Gansu Key Laboratories of Crop Genetic and Germplasm Enhancement and Aridland Crop Science, College of Agronomy, Gansu Agricultura University, Lanzhou 730070, P.R. China 10  

² School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P.R. China 

³ State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730000, P.R. China 

⁴ School of Earth and Environment and Institute of Agriculture, The University of Western Australia, 35 Stirling Hwy, Perth, Crawley, WA 6155, Australia & These authors contributed equally to this work

*Corresponding authors: Di Wang, e-mail: wangd@gsau.edu.cn, and Jin-Lin Zhang, 21   e-mail: jlzhang@lzu.edu.cn

Abstract  Salinity is one of the major abiotic stresses that impacts plant growth and reduces the  productivity of field crops. Compared to field plants, test tube plantlets offer a direct  and fast approach to investigate the mechanism of salt tolerance. Here we examined the ultrastructural and physiological responses of potato (Solanum tuberosum L. c.v. Longshu No. 3’) plantlets to gradient saline stress (0, 25, 50, 100 and 200 mM NaCl) with two consequent observations (two and six weeks, respectively). The results showed that, with the increase of external NaCl concentration and the duration of treatments, (1) the number of chloroplasts and cell intercellular spaces markedly decreased, (2) cell walls were thickened and even ruptured, (3) mesophyll cells and chloroplasts were gradually damaged to a complete disorganization containing more starch, (4) leaf Na and Cl contents increased while leaf K content decreased, (5) leaf  proline content and the activities of catalase (CAT) and superoxide dismutase (SOD) increased significantly, and (6) leaf malondialdehyde (MDA) content increased significantly and stomatal area and chlorophyll content decline were also detected. Severe salt stress (200 mM NaCl) inhibited plantlet growth. These results indicated that potato plantlets adapt to salt stress to some extent through accumulating osmoprotectants, such as proline, increasing the activities of antioxidant enzymes,such as CAT and SOD. The outcomes of this study provide ultrastructural and physiological insights into characterizing potential damages induced by salt stress for selecting salt-tolerant potato cultivars. 

Keywords: Potato plantlets, Saline stress, Ultrastructure, Antioxidant defense system,Ion distribution