Chlorophyll a/b Ratios and Photosystem Activity of Mesophyll and Bundle Sheath Fractions From Sodium-Deficient C₄ Plants

Abstract

Significantly lower chlorophyll a/b ratios were observed in mesophyll thylakoids extracted from sodium-deficient than normal C₄ plants of Amaranthus tricolor, Chloris gayana and Kochia childsii. The chlorophyll a/b ratio of bundle sheath thylakoids was not generally as significantly affected by sodium nutrition as the mesophyll thylakoids.

The lower chlorophyll a/b ratio in mesophyll thylakoids of sodium-deficient plants was associated with a lower photosystem II activity. The effect of sodium nutrition on photosystem I activity in the mesophyll thylakoids was dependent upon the species. Although no effect of sodium nutrition on photosystem I was observed in mesophyll thylakoids of K. childsii, photosystem I activity was greater in sodium-deficient than normal plants in A. tricolor.

The photosystem II and I activities of the bundle sheath thylakoids were not affected by sodium nutrition in either K. childsii or A. tricolor.