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No description available.

The response of in vitro-grown Solanum tuberosum L., cvs. Russet Burbank (RB) (salt-sensitive) and Sierra (S) (salt-tolerant) potatoes was investigated when [NaCl] was increased from 0 to 80 mM in the presence of 6, 20, and 30 mM [K] in a Murashige and Skoog (MS) basal medium. The tested growth parameters, Mg and Ca content, and K+/Na + ratios in the laminae and the roots were negatively affected as [NaCl] increased. The salt stress was relatively severe on growth of RB plants whereas the salt-tolerant (S) variety was affected to a lesser extent. There were indications that Na in the plant may promote Na translocation. In both cultivars, 22Na was not distributed equally in all plant parts; the lower lamina accumulated the highest amount (216 and 183 DPM mg -1 FW) followed by stem (197 and 182), petioles (187 and 168), and the upper lamina (149 and 121) for RB and S, respectively. / The salt resistance of S is associated not only with a superior capacity to accumulate high Na+ in the roots for osmotic adjustment, but also with resistance to Na movement to the shoot. / The effect of [K] on plant growth showed two main characteristics. In non-saline media, increasing [K] enhanced growth of S, while RB showed optimum growth when the normal (20 mM) level was present in the MS medium. In saline media, elevating [K] alleviated the growth reduction of RB at low salinity, and S at both low and high salinity. This ameliorative effect of K may be attributed to the suppression of both Na+ uptake, and Na + translocation in the plant.

The radiotracer methodology was combined with the Hoagland solution culture of growing soybean in a greenhouse to investigate the absorptions of phosphorus (P), calcium (Ca), and sodium (Na) as a function of salinity. Salt stress was varied by using zero to 120 mM NaCl. The research was initiated because of a need to increase soybean production in the saline soils of the semi-arid regions of the world. Although P absorption increased with time at each concentration of NaCl, increasing its concentrations ([NaCl]) to 120 mM reduced P uptake considerably. The addition of inorganic P (Pi) to the salt medium improved P absorption significantly (P < 0.0001) in stem, petiole, and roots. Polynomial regressions showed the relationship between 22Na activity and [NaCl] for leaves and petiole to be cubic (R2 = 1) while in the stem a quadratic relationship prevailed. A maximum of P and Na absorption was observed at 40 mM NaCl. The relationship between 32P activity and increasing [NaCl] was linear for the roots (a positive slope) and the stem (a negative slope). 45Ca and 32P dual labelling part of the experiments failed to produce results because an unexpectedly high degree of tissue quenching which prevented from obtaining the minimum counting requirements for separation. Shoot fresh and dry weights decreased linearly with increasing [NaCl] as did the root fresh and dry weights. Leaf chlorophyll content during the last week of the final harvest showed a linear relationship with time. Chlorophyll increased with time linearly when the growth medium contained zero and 40 mM NaCl; whereas a negative slope was obtained for 80 and 120 mM NaCl. It seems that P fertilization of the soil could ameliorate the salt effect. 22 Na uptake results indicated that there is a mechanism for exclusion of Na from soybean plant parts.

Utilization of salt-tolerant species or cultivars is one the most effective methods to address salinity problems in turfgrass management. The relative salt tolerance in 26 commercial creeping bentgrass (Agrostis stolonifera) cultivars during germination was studied. Final germination rate (FGR) and daily germination rate (DGR) decreased as salinity levels increased; however, DGR was more sensitive to salinity stress. Substantial differences in salt tolerance were observed in bentgrass cultivars, with 'Declaration', 'Seaside II', 'T-1 ', and 'Bengal' being the most salt-tolerant (averaged predicted salinity level causing 50% reduction of DGR [PSLD] = 8.2 g L -1 NaCl) and 'Tyee', 'Kingpin'. and 'SRI 150' being the most salt-sensitive (averaged PLSD = 6.5 g L -1 NaCl). Relative salinity tolerance in four populations of prairie junegrass (Koeleriu macrantha) collected from Colorado, Minnesota, Nebraska, and North Dakota and two improved turf-type cultivars from Europe ('Barleria' and 'Barkoel') was determined and compared to Kentucky bluegrass (Poa pratensis), perennial ryegrass (Lolium perenne), sheep fescue (Festuca ovina), hard fescue (F. brevipila), and tall fescue (F. arundinacea). All populations of prairie junegrass showed similar salt tolerance with an average of PSLF and PSLD being 7.1 and 5.3 g L -1 NaCl, respectively, comparable to Kentucky bluegrass and hard and sheep fescue but lower than tall fescue and perennial rye grass. In junegrasses, larger variations were observed in visual quality (VQ) than in electrolyte leakage (EL) and dry weight (OW) at vegetative growth stage. 'Barleria' junegrass showed the highest VQ, following two salt-tolerant grasses, tall fescue and sheep fescue. Junegrass - Nebraska population was the least salt-tolerant within the species, but still exhibited similar or higher tolerance than Kentucky bluegrass and perennial ryegrass cv. Arctic Green. Overall, junegrass was more salt sensitive during germination but more tolerant to salinity when mature.

The plant communities and individual plant species in and around a salt playa near Goshen, Utah County, Utah were studied in relation to three environmental gradients. Forty-eight stands were sampled by means of meter square gradients. Frequency data for all participating plant species were taken. Soil samples were collected from each site and analyzed to establish the environmental gradients (i.e., total soluble salts, soil moisture and hydrogen ion concentration. Results indicate that community vegetation types respond differentially to the three gradients and can be segregated on the basis of one or more of the gradients. The total soluble salts gradient was found to be the most influential of the three gradients. Correlation analysis indicates that 45% of the diversity measured within the plant communities can be accounted for by the three gradients. Individual plant species distribution patterns are strongly influenced by the three gradients. Niche width measurements exhibited no correlation with the measured gradients.

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Chan Yee-kwan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 108-131). / Abstracts in English and Chinese. / Thesis Committee --- p.i / Abstract --- p.ii / Acknowledgments --- p.v / General Abbreviations --- p.vii / Abbreviation for Chemicals --- p.x / Table of Contents --- p.xi / List of Figures --- p.xiv / List of Tables --- p.xv / Chapter 1. --- Literature Review / Chapter 1.1 --- Salinity as a global problem --- p.1 / Chapter 1.2 --- Salinity and agriculture --- p.2 / Chapter 1.3 --- Plant adaptation to salinity --- p.4 / Chapter 1.3.1 --- Salt secretion --- p.6 / Chapter 1.3.2 --- Ion transport --- p.8 / Chapter 1.3.2.1 --- Role of H+-ATPase in salt tolerance --- p.8 / Chapter 1.3.2.2 --- Potassium and sodium uptake --- p.13 / Chapter 1.3.2.3 --- Sodium efflux --- p.15 / Chapter 1.3.3 --- Osmotic adjustment --- p.20 / Chapter 1.3.3.1 --- Accumulation of mannitol --- p.21 / Chapter 1.3.3.2 --- Accumulation of proline --- p.23 / Chapter 1.3.3.3 --- Accumulation of glycinebetaine --- p.23 / Chapter 2. --- Materials and Methods / Chapter 2.1 --- Plant materials and growth conditions --- p.26 / Chapter 2.1.1 --- Surface sterilization of Arabidopsis seeds --- p.26 / Chapter 2.1.2 --- Determination of sub-lethal inhibitory doses of sodium --- p.27 / Chapter 2.1.3 --- Growth conditions of Arabidopsis seeds for total RNA extraction --- p.27 / Chapter 2.1.4 --- NaCl dosage tests --- p.28 / Chapter 2.1.5 --- Expression kinetic tests --- p.28 / Chapter 2.2 --- Isolation of total RNAs --- p.28 / Chapter 2.3 --- Isolation of genes differentially expressed in NaCl concentration by RAP-PCR --- p.30 / Chapter 2.3.1 --- RNA fingerprinting by RAP-PCR --- p.30 / Chapter 2.3.2 --- PCR reamplificatin of RAP products --- p.31 / Chapter 2.3.3 --- Cloning of differentially expressed genes --- p.33 / Chapter 2.3.3.1 --- Ligation of inserts into pCR-Script vector and transformation --- p.33 / Chapter 2.3.3.2 --- Ligation of inserts into pBluescript II KS (+) T-vector and transformation --- p.36 / Chapter 2.3.3.3 --- Screening of recombinant plasmids --- p.37 / Chapter 2.4 --- Sequencing of differentially expressed genes --- p.39 / Chapter 2.4.1 --- DNA cycle sequencing --- p.39 / Chapter 2.5 --- Northern blot hybridization of NaCl inducible genes --- p.40 / Chapter 2.5.1 --- RNA fractionation by formaldehyde gel electrophoresis --- p.40 / Chapter 2.5.2 --- Northern blotting --- p.41 / Chapter 2.5.3 --- Preparation of single-stranded DIG-labeled PCR probes --- p.41 / Chapter 2.5.3.1 --- Isolation of Total RNA --- p.41 / Chapter 2.5.3.2 --- Primer design --- p.42 / Chapter 2.5.3.3 --- PCR amplification of single-stranded DIG PCR probes --- p.43 / Chapter 2.5.4 --- Hybridization --- p.45 / Chapter 2.5.5 --- Stringency washes --- p.46 / Chapter 2.5.6 --- Chemiluminescent detection --- p.46 / Chapter 3. --- Results / Chapter 3.1 --- Determination of sub-lethal inhibitory doses of sodium --- p.48 / Chapter 3.2 --- Isolation of total RNA from A. thaliana treated with sodium chloride --- p.48 / Chapter 3.3 --- Isolation of genes differentially expressed in sodium concentration by RNA arbitrarily primed polymerase chain reaction RAP-PCR --- p.52 / Chapter 3.3.1 --- Differential cDNA fragments identified by RAP-PCR --- p.52 / Chapter 3.3.2 --- PCR reamplification of RAP products --- p.52 / Chapter 3.3.3 --- Cloning of selected RAP-fragments --- p.62 / Chapter 3.4 --- Nucleotide sequence analysis of selected RAP PCR clones --- p.65 / Chapter 3.5 --- Expression pattern analysis of salt inducible genes by northern blot hybridization --- p.75 / Chapter 3.5.1 --- Preparation of single-stranded digoxigenin (DIG)-labeled probes --- p.75 / Chapter 3.5.2 --- Dosage response of NaCl inducible genes --- p.79 / Chapter 3.5.3 --- Expression kinetics of NaCl inducible genes --- p.80 / Chapter 4. --- Discussion / Chapter 4.1 --- Isolation of RAP-PCR targets --- p.93 / Chapter 4.2 --- Expression of NaCl inducible P450 genes --- p.94 / Chapter 4.2.1 --- Cytochrome P450 CYP73A5 --- p.97 / Chapter 4.2.2 --- Cytochrome P450 CYP83A1 --- p.98 / Chapter 4.3 --- NaCl induction gene related to post-transcriptional activities --- p.99 / Chapter 4.3.1 --- Glycine-rich RNA binding protein (BAC F3F19) --- p.100 / Chapter 4.3.2 --- Chloroplast signal recognition particle (54CP) --- p.103 / Chapter 4.4 --- Conclusion --- p.106 / References --- p.108