Effects of chromium VI stress on photosynthesis, chlorophyll integrity, cell viability, and proline accumulation in lichen Ramalina farinacea.

Unal, Dilek; Isik, Nuray O.; Sukatar, Atakan

In order to contribute to understanding of the response to metal stress, Ramalina farinacea (L.) Ach. was treated with different concentrations of chromium (VI) (5, 15, and 30 mM of KCrO) for 1, 3, and 24 h, and alterations in the photosystem II photosynthetic quantum yield, pigment content, integrity of chlorophyll, cell viability, and proline accumulation were investigated. Significant alterations of the photosynthetic quantum yield ( F/ F) ratio were observed in response to the increase in chromium concentration. The F/ F ratio decreased in R. farinacea following 24-h treatment with 30 mM Cr solution. In present study, in both control and other plant groups treated with 5 mM Cr, the Chl a/b ratio was approximately within the range of 2.0–3.5. However, this ratio significantly decreased for the samples treated with 15 (exposure period of 24 h) and 30 mM; (exposure periods of 3 and 24 h) Cr. We also showed that cell viability of samples treated with 15 and 30 mM Cr significantly decreased. Accumulation of metal resulted in proline accumulation in R. farinacea thalli; however, when photodestructive effects on photosystem II occurred, proline intracellular concentration declined. On the basis of these results, we suggest that proline accumulation might not be the stress marker during heavy metal stress.

CHROMIUM; PHOTOSYNTHESIS; CHLOROPHYLL; PROLINE; RAMALINA

Russian Journal of Plant Physiology, 2010, Vol 57, Issue 5, p664

1021-4437

Academic Journal

10.1134/S1021443710050092