Responses of plastid pigments to desiccation and rehydration in the desert lichen Ramalina maciformis

Plastid pigments were analysed in thalli of the desert lichen Ramalina maciformis (Delile) Bory during a desiccation period of 30 d, and during rehydration following short-term (6 d) and long-term (30 d) desiccation. Desiccation and rehydration were performed in either constant light or constant dark. While further desiccation of freshly collected, air dried thalli did not affect the contents of violaxanthin and zeaxanthin, conversion from zeaxanthin to violaxanthin occurred during rehydration, regardless of whether lichens have been exposed to constant light or dark. In addition, de novo synthesis of violaxanthin took place during rehydration of short-term desiccated thalli exposed to constant light. Neither desiccation nor rehydration affected the contents of lutein, neoxanthin, antheraxanthin and β-carotene. Chlorophyll a and b, and α-carotene were slightly increased or decreased, respectively, during rehydration.