Abstract
The increase on the worldwide influx of solar ultraviolet radiation (UV-B) has inflicted a considerable challenge, due to its deleterious effects to live beings and pose a special threat to phyllosphere communities. However, UV-B influence on epiphytic yeasts associated with agricultural crops remains limited. Main aim of the present study was to determine the effect of ultraviolet-B radiation on the epiphytic yeast populations associated with strawberry under field conditions. Thus, strawberries (Fragaria x ananassa Duchesne cv. Oso Grande) were grown under three different treatments: a) environmental UV-B, b) enhanced UV-B and c) decreased UV-B; thereafter, their yeast epiphytic populations were analyzed by T-RFLP prior to yeast isolation, identification and in vitro test for the sensitivity against UV-B. Our results demonstrated that UV-B radiation did not significantly affect the strawberry epiphytic yeast populations. However, isolates directly exposed to radiation, generally revealed morphological abnormalities and a diminishing Short Research Article British Microbiology Research Journal, 4(10): 1105-1117, 2014 1106 value in the percentage of survival, although they remained constant after 240 min of exposure. The increase in UV-B radiation was not sufficient to affect the dynamics and composition of epiphytic yeast communities from strawberry, there was a clear morphotype shift towards the selection of pigmented isolates.
Highlights
World climate has been negatively affected by the global warming influence
Considering the possible impacts caused by climate changes, this work aimed to test the hypothesis that UV-B radiation would have an effect on epiphytic yeast communities associated to strawberry in field conditions as well as to determine the sensitivity of some yeasts exposed to this wavelength (280-320nm)
Analysis of Similarity (ANOSIM) indicated that there were no significant differences between the treatments based on the profiles obtained by using the restriction enzyme Hinf-I (r=-0.048; p=0.642) nor those obtained with Mbo-I (r=-0.121; p=0.963)
Summary
World climate has been negatively affected by the global warming influence. The decrease in the ozone level is more evident in the polar regions, its effects can be observed all around the world and as a direct consequence the daily influx of solar radiation has increased on many ecosystems [2]. Within these radiations, ultraviolet-B (UV-B; 290-320nm) is one of the most harmful to biologically active molecules due to its direct absorption by nucleic acids and proteins [3,4,5] and poses a special threat to living organisms. The repair mechanisms displayed by yeasts are different from other organisms: radiation exposure leads to cell response activation, regardless DNA damages, which trigger the physiological response that generates a faster signaling system and, a more effective repair mechanism [13]
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