In Vitro Selection of a Salt-tolerant Embryogenic Line in Habanero Pepper (Capsicum chinense Jacq.)

The effect of NaCl salinity on growth and development of somatic embryos of Habanero pepper was examined. Addition of 75 and 100 mm NaCl into the medium greatly increased the growth and development of somatic embryos and both of these concentrations favored the proliferation of somatic embryos. However, supplementation of 200 and 300 mm NaCl to the medium showed a negative effect on the growth and development of somatic embryos. Concentration increases of NaCl provoked a significant reduction of the embryos survival rate with the average lethal dose (46%) being registered in the treatment of 100 mm. Furthermore, a lower tolerance to salt stress (NaCl) was observed in deformed somatic embryos. Concentrations of 200 and 300 mM NaCl significantly delayed development in the surviving embryos in both treatments. These embryos remained at the globular stage throughout culture time. At 75 mm NaCl, most of the embryos were observed in the torpedo stage. However, the embryos exposed to 100 mm NaCl were observed mainly in globular and cotiledonar stages. It is quite likely that the transition from one intermediate stage of development to another occurs rapidly. With the exception of the concentration at 300 mm NaCl, salt stress stimulated embryonic germination, particularly at 100 mm NaCl. The content of proline in somatic embryos increased substantially in response to salinization. The results suggest that somatic embryos of C. chinense can tolerate concentrations of NaCl up to 100 mm without their development being affected. Moreover, they have sufficient cellular mechanisms to tolerate salinity at relatively higher levels.