Neither glutamate nor alanine but arginine sensitizes BY-2 cells to arsenate.

Arsenic is toxic for plants. Our previous results showed that the application of proline enhanced the sensitivity of tobacco BY-2 cells to arsenate. In order to clarify the enhancement mechanism, we investigated the effects of other amino acids on the arsenate-stressed BY-2 cells. Glutamate at up to 10 m m did not affect the cell growth in the absence or presence of arsenate. Arginine at up to 10 m m did not affect the growth in the absence of arsenate but arginine at 10 m m enhanced the inhibition of the cell growth by arsenate. Alanine at up to 10 m m did not affect the cell growth under nonstressed condition but alanine at 10 m m significantly improved the cell growth under arsenate stress. These results suggest that alanine mitigates arsenate stress in BY-2 cells and that arginine like proline enhances the sensitivity of BY-2 cells to arsenate.

Exogenous proline enhances the sensitivity of Tobacco BY-2 cells to arsenate.

Arsenic causes physiological and structural disorders in plants. Proline is accumulated as a compatible solute in plants under various stress conditions and mitigates stresses. Here, we investigated the effects of exogenous proline on tobacco Bright Yellow-2 (BY-2) cultured cells under [Formula: see text] stress. Arsenate did not inhibit BY-2 cell growth at 40 and 50 µM but did it at 60 µM. Proline at 0.5 to 10 mM did not affect the cell growth but delayed it at 20 mM. At 40 µM [Formula: see text], neither 0.5 mM nor 1 mM proline affected the cell growth but 10 mM proline inhibited it. In the presence of [Formula: see text], 10 mM proline increased the number of Evans Blue-stained (dead) cells and decreased the number of total cells. Together, our results suggest that exogenous proline does not alleviate arsenate toxicity but enhances the sensitivity of BY-2 cells to arsenate.