Eui Shik Rha

Salt-Induced Changes in Two Canola Cultivars Differing in Salt Tolerance

Responses of 20 d-old plants of two Brassica napus L. cultivars Dunkeld and Cyclon to NaCl salinized soil [electrical conductivity 2.4 (control), 4.0, 8.0 or 12.0 dS m−1] were examined. The salt tolerant line Dunkeld had significantly higher fresh and dry masses of shoots, and seed yield than salt sensitive line Cyclon in all salinities. The effect of salt stress on reduction in total leaf soluble sugars was markedly greater in Dunkeld as compared to that in Cyclon. No effect of salt stress was observed on leaf soluble proteins but there was a slight increase in total free amino acids of both cultivars. Leaf proline content increased markedly in both cultivars and Dunkeld had greater proline content than Cyclon at all salinities. Salt stress had no significant effect on seed oil content and erucic acid content of seed oil, however, content of glucosinolates in the seed meal increased and Cyclon had greater content of glucosinolates than Dunkeld.

Role of Bacillus licheniformis in Phytoremediation of Nickel Contaminated Soil Cultivated with Rice

Heavy metal contamination in soil is an important environmental problem and it has negative effect on agriculture. Bacteria play a major role in phytoremediation of heavy metals contaminated soil. In this study, the effect of Bacillus licheniformis NCCP-59, a halophilic bacterium isolated from salt mines near Karak, Pakistan, were determined on a three week old greenhouse grown seedling and germinating seeds of two rice varieties (Basmati-385 (B-385) and KSK-282) in soil contaminated with different concentrations (0, 100, 250, 500, and 1000 ppm) of Nickel. Nickel significantly reduced the germination rate and germination percentage mainly at 500 and 1000 ppm. Significant decrease in ion contents (Na, K, and Ca) was observed while Ni ion concentration in the plant tissues increases as the concentration of Ni applied increases. The photosynthetic pigments (chlorophyll a (chl a), chlorophyll b (chl b), and carotenoids) were also decreased by the application of different concentrations of Ni. Total protein and organic nitrogen were found to be reduced at higher concentrations of Nickel. Inoculation of Bacillus Licheniformis NCCP-59 improved seed germination and biochemical attribute of the plant under Ni stress. It is clear from the results that the Bacillus Licheniformis NCCP-59 strain has the ability to protect the plants from the toxic effects of nickel and can be used for the phytoremediation of Ni contaminated soil.

Salt-induced changes in photosynthetic activity and growth in a potential medicinal plant Bishop’s weed (Ammi majus L.)

Sixty seven-days-old plants of Ammi majus L. were subjected for 46 d to sand culture at varying concentrations of NaCl, i.e. 0 (control), 40, 80, 120, and 160 mM. Increasing salt concentrations caused a significant reduction in fresh and dry masses of both shoots and roots as well as seed yield. However, the adverse effect of salt was more pronounced on seed yield than biomass production at the vegetative stage. Calculated 50 % reduction in shoot dry mass occurred at 156 mM (ca.15.6 mS cm−1), whereas that in seed yield was at 104 mM (ca.10.4 mS cm−1). As in most glycophytes, Na+ and Cl− in both shoots and roots increased, whereas K+ and Ca2+ decreased consistently with the successive increase in salt level of the growth medium. Plants of A. majusmaintained markedly higher K+/Na+ ratios in the shoots than those in the roots, and the ratio remained more than 1 even at the highest external salt level (160 mM). Net photosynthetic (PN) and transpiration (E) rates remained unaffected at increasing NaCl, and thus these attributes had a negative association with salt tolerance of A. majus. Proline content in the shoots increased markedly at the higher concentrations of salt. Essential oil content in the seed decreased consistently with increase in external salt level. Overall, A. majusis a moderately salt tolerant crop whose response to salinity is associated with maintenance of high shoot K+/Na+ ratio and accumulation of proline in shoots, but PN had a negative association with the salt tolerance of this crop.

Salinity induced changes in cell membrane stability, protein and RNA contents

Seedlings of sugar beet ( Beta vulgarus L.) were used at salinity levels of 0 (control), 4.7, 9.4 and 14.1 dS m-1 to determine the effect of salt on vegetative growth, relative water content, cell membrane stability, protein and RNA contents in sand culture experiment. Fresh and dry weights of plants, shoots and roots decreased significantly with increasing salt concentration. Salinity significantly reduced leaf area and relative water content while cell membrane injury increased with increasing salt concentration. Leaf protein content decreased significantly and sodium dodecyl sulphate-polyacrylamide gel electrophresis (SDS-PAGE) analysis showed significant change in protein profiles in salt treated samples, which suggests that NaCl altered protein pattern. Salinity induced RNA degradation with increasing salt level. Cell membrane stability exhibited negative correlation with fresh and dry weight, leaf area, leaf water content and total protein content. There was also a significant positive correlation between cell membrane injury and RNA degradation. Key words : Salt stress, membrane injury, growth, RWC, protein activity, RNA, Beta vulgarus L.

Biosorption of heavy metals by Pseudomonas species isolated from sugar industry

Heavy metal-resistant bacteria can be efficient bioremediators of metals and may provide an alternative or additional method to conventional methods of metal removal. In this study, 10 bacterial isolates were isolated from soil samples of a sugar industry, located at Peshawar, Pakistan. Morphological, physiological, and biochemical characteristics of these isolates were observed. Sequence analysis (16S ribosomal RNA) revealed that isolated strains were closely related to the species belonging to the genera Pseudomonas, Arthrobacter, Exiguobacterium, Citrobacter, and Enterobacter. Bacterial isolates were resistant with a minimum inhibitory concentration (500–900 ppm) to lead ion (Pb2+), (500–600 ppm) nickel ion (Ni2+), (500–800 ppm) copper ion (Cu2+), and (600–800 ppm) chromium ion (Cr3+) in solid media. Furthermore, biosorption of metals proved considerable removal of heavy metals by isolated metal-resistant strains. Pseudomonas sp. reduced 37% (Pb2+), 32% (Ni2+), 29% (Cu2+), and 32% (Cr3+) and was thus found to be most effective, whereas Enterobacter sp. reduced 19% (Pb2+), 7% (Ni2+), 14% (Cu2+), and 21% (Cr3+) and was found to be least effective. While average reduction of Pb2+, Ni2+, Cu2+, and Cr3+ by Citrobacter sp. was found to be 24%, 18%, 23%, and 27%, respectively, among recognized species. This study revealed that Pseudomonas sp. may provide a new microbial community that can be used for enhanced remediation of contaminated environment.

Cell Membrane Stability (CMS): A Simple Technique to Check Salt Stress Alleviation Through Seed Priming with GA3 in Canola

Cell membrane stability (CMS) technique was used to assess whether salt tolerance could be improved in canola (Brassica napus L.) by soaking the seeds for 10 h in distilled water (Control), 100, 150 and 200 mg l−1 GA3. The electrical conductivity (EC) values of the NaCl solution were 0 (control), 4.7, 9.4 and 14.1 dS m−1 NaCl. Seed priming increased the fi nal germination percentage and the germination rate (1/t50, where t50 is the time to 50% of germination) under saline condition. Priming also alleviated the adverse effect of salt stress on canola in terms of fresh and dry weights of plants, roots and shoots. Similarly leaf area, leaf water contents (RWC) and chlorophyll contents (SPAD value) were signifi cantly higher in plants raised from seeds primed with GA3 as compared with those raised from seeds treated with distilled water. All pre-sowing seed treatments decreased electrolyte leakage of steep water as compared to that of non-primed seeds even after 24 h of soaking. Similarly plants raised from seeds primed with GA3, showed signifi cantly lower cellular injury than seeds treated with distilled water.

Mechanisms involved in rapid swelling of sesame (Sesamus indicum) pollen

Abstract Mature pollen from dehisced anther of sesame (Sesamus indicum L.) have 12 furrow apertures. Pollen were hydrated with distilled water and it was found that upon hydration pollen swelled in less than a second. Macallums staining solution revealed that the potassium (K) existed only at the furrow aperture areas of pollen. Energy dispersive X‐ray analysis (EDX) verified staining results of K at the furrow aperture areas of pollen. These results demonstrate that sesame pollen swell instantly upon hydration in water and there could be a relationship between K, located at the furrow aperture area, and rapid swelling of pollen.