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Many aquatic organisms respond phenotypically, through morphological, behavioral, and physiological plasticity, to environmental changes. The small-size cladoceran Bosmina longirostris, a dominant zooplankter in eutrophic waters, displayed reduced growth rates in response to the presence of a toxic cyanobacterium, Microcystis aeruginosa, in their diets. The magnitude of growth reduction differed among 15 clones recently isolated from a single population. A significant interaction between clone and food type indicated a genetic basis for the difference in growth plasticity. The variation in phenotypic plasticity was visualized by plotting reaction norms with two diets. The resistance of each clone to dietary cyanobacteria was measured as the relative change in growth rates on the “poor” diet compared with the “good” diet. The enhanced resistance to M. aeruginosa in B. longirostris was derived from both the reduced slope of reaction norms and the increased mean growth rates with two diets. The large clonal variation within a B. longirostris population may contribute to local adaptation to toxic cyanobacteria and influence ecosystem function via clonal succession. [ABSTRACT FROM AUTHOR]

Late embryogenesis abundant (LEA) genes were confirmed to confer resistance to drought and water deficiency. An LEA gene from Tamarix androssowii (named TaLEA) was transformed into Xiaohei poplar (Populus simonii × P. nigra) via Agrobacterium. Twenty-five independent transgenic lines were obtained that were resistant to kanamycin, and 11 transgenic lines were randomly selected for further analysis. The polymerase chain reaction (PCR) and ribonucleic acid (RNA) gel blot indicated that the TaLEA gene had been integrated into the poplar genome. The height growth rate, malondialdehyde (MDA) content, relative electrolyte leakage and damages due to salt or drought to transgenic and non-transgenic plants were compared under salt and drought stress conditions. The results showed that the constitutive expression of the TaLEA gene in transgenic poplars could induce an increase in height growth rate and a decrease in number and severity of wilted leaves under the salt and drought stresses. The MDA content and relative electrolyte leakage in transgenic lines under salt and drought stresses were significantly lower compared to those in non-transgenic plants, indicating that the TaLEA gene may enhance salt and drought tolerance by protecting cell membranes from damage. Moreover, amongst the lines analyzed for stress tolerance, the transgenic line 11 (T11) showed the highest tolerance levels under both salinity and drought stress conditions. These results indicated that the TaLEA gene could be a salt and drought tolerance candidate gene and could confer a broad spectrum of tolerance under abiotic stresses in poplars. [ABSTRACT FROM AUTHOR]

Late embryogenesis abundant (LEA) genes were confirmed to confer resistance to drought and water deficiency. An LEA gene from Tamarix androssowii (named TaLEA) was transformed into Xiaohei poplar (Populus simonii × P. nigra) via Agrobacterium. Twenty-five independent transgenic lines were obtained that were resistant to kanamycin, and 11 transgenic lines were randomly selected for further analysis. The polymerase chain reaction (PCR) and ribonucleic acid (RNA) gel blot indicated that the TaLEA gene had been integrated into the poplar genome. The height growth rate, malondialdehyde (MDA) content, relative electrolyte leakage and damages due to salt or drought to transgenic and non-transgenic plants were compared under salt and drought stress conditions. The results showed that the constitutive expression of the TaLEA gene in transgenic poplars could induce an increase in height growth rate and a decrease in number and severity of wilted leaves under the salt and drought stresses. The MDA content and relative electrolyte leakage in transgenic lines under salt and drought stresses were significantly lower compared to those in non-transgenic plants, indicating that the TaLEA gene may enhance salt and drought tolerance by protecting cell membranes from damage. Moreover, amongst the lines analyzed for stress tolerance, the transgenic line 11 (T11) showed the highest tolerance levels under both salinity and drought stress conditions. These results indicated that the TaLEA gene could be a salt and drought tolerance candidate gene and could confer a broad spectrum of tolerance under abiotic stresses in poplars. [ABSTRACT FROM AUTHOR]