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1999 (3)
1Author    Sunkar Ramanjulu3, Werner Kaiser3, Karl-Josef Dietz3-Requires cookie*
 Title    Salt and Drought Stress Differentially Affect the Accumulation of Extracellular Proteins in Barley  
 Abstract    Barley (Hordeum vulgare) was grown for eight days in the presence of a range of salt concentrations or subjected to repeated cycles of wilting and rehydration. Changes in apoplastic protein content, protein pattern, enzymic activities and ion composition were in­ vestigated under salinity and drought. The protein content of intercellular washing fluid (IW F) increased 2.5-to 3.0-fold when the NaCl concentration in the growth medium was increased from 0 to 100 mM. The elevated protein content was the result of a general increase in most polypeptides and a pronounced increase in the abundance of specific polypeptides of apparent molecular masses of 15, 21, 22, 26, 36, 40 and 62 kDa. Conversely, the IW F protein content decreased during wilting similar as after application of colchicin, cytochalasin B or cycloheximide suggesting that inihibition of protein synthesis or vesicle transport may be the cause for the decrease in apoplastic protein content and enzyme activities in dehydrat­ ing plant tissue. The changes in apoplastic protein content were accompanied by stress-spe-cific alterations in activities of apoplastic enzymes. The greater apoplastic protein content was the consequence of stimulated protein synthesis in the presence of NaCl, as evidenced by increased incorporation of [35S]-methionine into IW F protein. The results demonstrate that the leaf apoplast is a compartment which sensitively and differentially responds to drought and salinity with consequences for plant growth. 
  Reference    Z. Naturforsch. 54c, 337—347 (1999); received February 5/February 23 1999 
  Published    1999 
  Keywords    Apoplast, Barley, Drought, Hydrolytic Enzymes, Polypeptide, Salinity 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-0337.pdf 
 Identifier    ZNC-1999-54c-0337 
 Volume    54 
2Author    Tibor Janda3, Gabriella Szalai3, Catherine Giauffretb, Emil Páldi3, Jean-M Arc DucruetcRequires cookie*
 Title    The Thermoluminescence 'Afterglow' Band as a Sensitive Indicator of Abiotic Stresses in Plants  
 Abstract    Single turn-over xenon flashes induce a thermoluminescence (TL) B-band centred near 35 °C. The far-red illumination of leaves at non-freezing temperatures induces a band peaking at around 45 °C (afterglow or AG-band), together with a downshifted B-band peaking be­ tween 15 °C and 28 °C. In control, unfrozen wheat plants, the Tmax of the B-band induced after 30 s far-red light at 0 °C was approx. 1 5 -1 8 °C. In maize plants grown under the same conditions, this far-red-induced downshift was not so strong, since the B-band peaked at 2 8 -30 °C. Both a decline in the AG-band and a reversal of the downshift of the B-band were observed after short-term freezing in several plant species. There was usually a sudden drop in the AG-band below a critical freezing temperature. However, while in wheat plants a weak TL emission could be seen between 4 0 -5 0 °C in frozen samples, in cold-sensitive maize plants this was completely suppressed and only the B-band could be detected. In cold-har­ dened wheat plants the temperature at which the AG-band was suppressed was lower than in non-hardened plants. Drought and short-term heat stress also affect the AG-band. As the AG-band was found to be more sensitive to several types of stresses than the B-band, it can be used as a sensitive stress indicator. However, the behaviour of the AG-band depends on several factors (for example the age of the leaf, etc.), which must be controlled if different species or varieties are to be compared. 
  Reference    Z. Naturforsch. 54c, 629 (1999); received O ctober 31 1998/January 25 1999 
  Published    1999 
  Keywords    Afterglow, Drought, Freezing, Heat Stress, Thermoluminescence 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-0629.pdf 
 Identifier    ZNC-1999-54c-0629 
 Volume    54 
3Author    Sergi Munné-Bosch3, Karin Schwarz, Leonor Alegre3Requires cookie*
 Title    in Rosmarinus officinalis L. and Melissa officinalis L  
 Abstract    Summer diurnal variations of photosynthesis and a-tocopherol content were measured in relation to natural drought in field-grown rosemary (Rosmarinus officinalis L.) and lemon balm (Melissa officinalis L.) plants. During the summer relative water contents (RW C) of ca. 40% in Rosmarinus officinalis and ca. 30% in Melissa officinalis were attained, indicating severe drought. Both species showed similar diurnal patterns of net C 0 2 assimilation rates (A) with a wide plateau of maximum photosynthesis at midday in the absence of drought and one peak of maximum photosynthesis early in the morning under drought conditions. Net C 0 2 assimilation rates decreased by ca. 75% due to drought in both species. Melissa officinalis plants showed a significant decrease in the relative quantum efficiency of PSII photochemistry (4>psn), ratio of variable to maximum fluorescence yield (F J F m) and chloro­ phyll content of leaves by ca. 25% under drought conditions at midday. In contrast, cJ)pSI1, F J F m and chlorophyll content remained constant throughout the experiment in R. officinalis plants. Although the non-photochemical quenching of chlorophyll fluorescence increased from ca. 1.8 to 3 and the a-tocopherol content rose fifteen fold in both species in response to drought, only R. officinalis plants were able to avoid oxidative damage under drought conditions by the joint increase of carotenoids and a-tocopherol. 
  Reference    Z. Naturforsch. 54c, 698—7 (1999); received November 17 1998/March 20. 1999 
  Published    1999 
  Keywords    a-Tocopherol, Photosynthesis, Drought, Rosmarinus officinalis, Melissa officinalis 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-0698.pdf 
 Identifier    ZNC-1999-54c-0698 
 Volume    54