In Vitro Selection of Salt Tolerant Calli Lines and Regeneration of Salt Tolerant Plantlets in Mung Bean (Vigna radiata L. Wilczek)

Abstract

Salinity is one of the important abiotic factors in limiting plant productivity (Munns, 2002). 19.5% of the irrigated agricultural land is considered saline (Flowers & Yeo, 1995). Although minerals are essential for plants, their excess quantity in the soil is injurious to plants. Plants exposed to saline environment suffer from ion excess or water deficit and oxidative stress linked to the production of reactive oxygen species (ROS), which cause damage to lipids, proteins and nucleic acids (Hernandez, et al., 2000). Oxidative stress is considered to be one of the major damaging factors in plant cells exposed to salinity (Gossette, et al., 1994; Hernandez, et al., 1995; Khan & Panda, 2002; Queiros et al., 2007). The process of salt response and tolerance has been studied at the whole plant level (Hasegawa et al., 2000; Jogeshwar, et al., 2006). However the structural complexity of the whole plant makes it difficult to separate systemic from cellular salinity tolerance mechanism (Hawkins & Lips, 1997). The importance of plant tissue culture in the improvement of salt tolerance in plants has been pointed long back (Dix, 1993; Hasegawa, et al., 1994; Nabors et al., 1980; Tal 1994). In recent years tissue culture techniques are being used as a useful tool to elucidate the mechanism involved in salt tolerance by using in vitro selected salt tolerant cell lines (Davenport, et al., 2003; Gu, et al. 2004; Lutts et al., 2004 ; Naik & Harinath, 1998; Rao & Patil. 1999; Venkataiah. et al., 2004). Besides, these lines have been used to regenerate salt tolerant plants (Chen et al., 200; Jaiwal & Singh, 2001; Miki et al. 2001; Ochatt et al., 1999; Rao & Krupanidhi, 1996; Shankhdhar, et al., 2000). The selection of crop varieties for greater tolerance to saline environment will allow greater productivity from large saline lands.