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Abstract Detail

Bryological and Lichenological Section/ABLS

McLetchie, D. Nicholas [1], Alvarenga, Lisi [2], Machado, Priscila [3].

The effect of long periods of reduced light on recovery from desiccation in an epiphyllous bryophyte.

Desiccation tolerance (DT) and the environmental factors influencing DT is well studied for bryophytes living in dry environments such as deserts. Bryophytes occurring in the wet tropics are also subjected to desiccation, but the weather patterns causing desiccation in the wet tropics are different than deserts. While desert plants are subjected to long periods of dryness and cold nights, tropical epiphytic and epiphyllous bryophytes, are subjected to intermittent drying and warm nights. When plants are wet at night, high night time temperatures result in high respiration rates, reducing carbon resources needed to repair cellular function after rehydration. Frequent wet-dry cycles and night time respiration rates result in a very unique stress that is understudied. The goal of this study was test for an effect of long periods of darkness on recovery of an epiphyllous bryophyte. In an Atlantic forest fragment in Brazil, we conducted two experiments to test the effect on long periods of darkness on recovery from desiccation. First, host leaves colonized with Crossomitrium patrisiae (an epiphyllous moss) were wrapped in aluminium foil to block light for one week. These leaves, together with a paired leaf that was not wrapped in foil were collected (n= 12 pairs). The health of photosystem II (PSII) of C. patrisiae was assayed using chlorophyll fluorescence in hydrated plants. Plants were then placed under desiccation conditions (77% relative humidly). PSII was then assayed on plants immediately and 24 h after rehydration. Second, host leaves were collected in the field and C. patrisiae was removed from the host leaves and placed into six twenty-four well plates, three of which were wrapped in foil for two days to reduce light and the other three was exposed to ambient light. Plants were then placed in desiccation conditions as in the first study. PSII was taken on each plant immediately and 24 after rehydration. In the first experiment, plants subjected to a dark period had more efficient PSII prior to desiccation than plants in ambient light. In both experiments plants exposed to ambient light conditions had better recovery from desiccation than plants exposed to long periods of darkness. These results support the idea that night time respiration and possibly the low light conditions of a tropical forest understory can influence recovery from desiccation. Whether tropical plants have unique mechanisms to tolerate topical desiccation conditions needs to be studied.

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1 - University Of Kentucky, Department Of Biology, 101 Morgan Build., Lexington, KY, 40506-0225, USA
2 - Universidade Federal de Pernambuco, Centro Acadêmico de Vitória, Rua Alto do Reservatório, s/n, Bela Vista, Vitória de Santo Antão, Pernambuco, 55608-680, Brazil
3 - Universidade Federal de Juiz de Fora - Programa de Pós-graduação em Ec, Instituto de Ciências Biológicas - Departamento de Botânica, Rua José Lourenço Kelmer, s/n - Campus Universitário, Bairro São Pedro, Juiz de Fora , Minas Gerais, 36036-900, Brazil

Abiotic stress.

Presentation Type: Oral Paper:Papers for Sections
Session: 38
Location: Salon 8/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 10:45 AM
Number: 38009
Abstract ID:819
Candidate for Awards:None

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