Desiccation tolerance in the Antarctic moss Sanionia uncinata

BACKGROUND: One of the most extreme environments on our planet is the Maritime Antarctic territory, due to its low-water availability, which restricts the development of plants. Sanionia uncinata Hedw. (Amblystegiaceae), the main colonizer of the Maritime Antarctic, has effective mechanisms to tolerate this environment. It has been described that the tolerance to desiccation is mediated by the hormone abscisic acid (ABA), antioxidants systems, accumulation of compatible solutes and proteins of the late embryogenesis abundant (LEA). However, to date, these mechanisms have not been described in S. uncinata. Therefore, in this work, we postulate that the tolerance to desiccation in the Antarctic moss S. uncinata is mediated by the accumulation of ABA, the osmolytes proline and glycine betaine, and dehydrins (an LEA class 11 proteins). To demonstrate our hypothesis, S. uncinata was subjected to desiccation for 24 h (loss in 95% of water content), and the effects on its physiological, photosynthetic, antioxidant and biochemical parameters were determined. RESULTS: Our results showed an accumulation of ABA in response to water loss, and the activation of protective responses that involves an increment in levels of proline and glycine betaine, an increment in the activity of antioxidant enzymes such as SOD, CAT, APX and POD, and the accumulation of dehydrins proteins. CONCLUSION: The results showed, suggest that S. uncinata is a desiccation-tolerant moss, property mediated by high cellular plasticity regulated by ABA.

Biomonitoring of metal deposition by using moss transplant method through Hypnum cupressiforme (Hedw.) in Mussoorie.

Metals Cu, Zn, Cd and Pb were surveyed at 14 sampling sites by using moss Hypnum cupressiforme through active monitoring technique. Samples were transplanted in all four directions of Mussoorie city and were harvested after exposure of four months (representing each season) to analyze metal precipitation and its trend at different sites during 2005. Bioaccumulation ability for metals was evaluated seasonally exhibiting maximum in summer followed by winter and minimum in rainy season. However, at some places Cu shows highly significant values in rainy season in comparison to winter. In case of Zn and Pb significantly different (p < or = 0.05) values were observed between summerand rainy season. Baseline concentration of Cu, Pb and Zn was significantly different at 5% in comparison to other transplant sites. Result indicates Dhanaulti as most polluted location might be due to higher tourist activity and vehicular load, whereas, same was found low at Chamba might be due to place was free from pollution sources or away from in proximity to road and have low human interference. The present study allows us to determine the extent of the area affected by metal precipitation load in different rural and urban areas and abundance of metals in order of Zn > Pb > Cu > Cd.