Estudio de las respuestas fenotÃpicas y fisiolÃ³gicas del musgo ...

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Abstract The plant growth and productivity are affected by various abiotic stress factors. The water deficit is a major abiotic stresses affecting growth and yield of agricultural crops. In general, drought occurs when the available soil water is reduced and atmospheric conditions cause continuous loss of water through transpiration and evaporation. In nature there are plants that have developed strategies for tolerance to water deficit such as bryophytes are among the first plants that dominated terrestrial life from more than 400 million years and are now distributed worldwide from the tropics to Antarctica (Proctor and Tuba 2002; Robinson et al. 2003). Adaptation to the land is attributed to the resistance to desiccation stress causes rapid dehydration of the cells (Oliver et al. 2000). In this work phenotypic and physiological studies conducted in the moss Ceratodon stenocarpus which has not been identified, in addition to the culture system in vitro. Were carried out in protonema cells obtained through germination of spores mixture exposed for 25 days at concentrations of osmotic agents (sorbitol and mannitol of 400-1000 mM NaCl and 200-500 mM). Protonemal moss tissue were to be tolerant to osmotic stress at concentrations of 400-800 mM, these tissues also showed the ability to recover their normal metabolism, after 85 days in control medium. For tests protonema cells under salt stress for 25 days, they showed tolerance at concentrations of 200-500 mM, the same way had the ability to regain pigmentation to be transferred to control medium in a time of 19 days. Moreover we evaluated the involvement of abscisic acid (ABA) in protonema cells exposed to high concentrations of osmotic agent (sorbitol 800-2000 mM) for ten days, resulting phenotypes of tolerance at all concentrations. Moss also had the ability to recover their normal metabolism in a time of 35 days, by transferring protonema cells to control medium.
Also the involvement of ABA in moss C. stenocarpus to contend with the stress was overwhelming to tolerate salt concentrations of 400-800 mM when exposed to these concentrations for ten days. Furthermore, our study model proved to be tolerant to freezing stress when subjected to temperatures of -10 º C, -20 º C and 76 º C for seven days, with the participation of ABA. In carrying out physiological studies through the measurement of photosynthetic activity of PSII in the cells of protonema subject in each of abiotic stress, this behavior showed a general decline during abiotic stress, but this showed recovery of their activity transferring the medium control tissues. According to our studies of the moss protonema cells of C. stenocarpus we propose as a model to study the responses of tolerance to biotic stresses specifically osmotic, salinity and freezing.
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Estudio de las respuestas fenotÃpicas y fisiolÃ³gicas del musgo ...