Poster: Salinity

Abs # 157: Salinity-induced chloroplast degradation is dependent on light

Presenter:	Mitsuya, Shiro , mituya@mbox.media.nagoya-u.ac.jp
Authors	Mitsuya, Shiro  (A)   Kawasaki, Michio  (A)   Taniguchi, Mitsutaka  (A)   Miyake, Hiroshi  (A)
Affiliations:	(A): Graduate School of Bioagricultural Sciences, Nagoya University

The effects of sodium chloride on Na, K and Cl contents, chlorophyll content and foliar ultrastructure in rice seedlings were investigated under light and dark conditions. The seedlings were grown in water for 7 d under light condition and were cultured with various NaCl concentrations for 24 h under light and dark conditions. The stressed seedlings had significantly higher Na and Cl contents in the 3rd leaves. The leaves under light condition had higher Na and Cl contents than under dark condition when treated with the same concentrations of NaCl in the media. K content was scarcely changed by salt treatment under both conditions. The chlorophyll content in the 3rd leaves of the seedlings cultured under light condition was decreased with increasing NaCl concentrations in the medium but it was not changed under dark condition. In mesophyll of the 3rd leaves of the seedlings cultured with NaCl under light condition, the thylakoids of chloroplasts were swollen and showed a wavy configuration. Under dark condition, however, the thylakoids appeared intact under saline conditions even when the leaves accumulated higher contents of Na and Cl than in light condition. The present study suggests that the damages in the chloroplasts, such as the decrease of the chlorophyll content and the degradation of the thylakoids, were caused by light-dependent reaction and not directly by accumulation of excess salt.