Ericifolin: an eugenol 5-O-galloylglucoside and other phenolics from Melaleuca ericifolia

Ericifolin, an eugenol 5-O-beta-(6'-O-galloylglucopyranoside) possessing the naturally unknown phenolic moiety, 5-hydroxyeugenol, together with the two new phenolics, 2-O-p-hydroxybenzoyl-6-O-galloyl-(alpha/beta)-4C1-glucopyranose and 3-methoxyellagic acid 4-O-rhamnopyranoside have been isolated from the antibacterial leaves extract of Melaleuca ericifolia. In addition, 19 known phenolics were also separated and characterized. All structures were elucidated on the basis of analysis of 1H, 13C NMR, HMQC, HMBC and FTMS spectral data.     

Salinity tolerance in some mangrove species from Pakistan

Growth, ionic and water relations of three mangrove species viz. Avicennia marina, Ceriops tagal and Rhizophora mucronata werestudied in different seawater concentrations (0, 25, 50, 75 and 100%).All mangrove species showed optimal growth at 50% seawater. Relativelymore biomass was accumulated by R. mucronata while C. tagalhad the tallest individuals. Tissue water potential became more negativewith the increase in salinity and stomatal conductance was decreased in allplants. Higher stomatal conductance was noted in R. mucronata,followed by A. marina and C. tagal. Sodium and chloride ionsincreased with the increase in salinity and this accumulation was muchhigher in A. marina.     

水淹胁迫下10个树种某些生理指标的变化及其耐水淹能力的比较

以游离脯氨酸和丙二醛(MDA)含量及相对电导率为指标,比较了水淹条件下10个树种的耐水淹能力。结果表明,水淹胁迫下,不同树种的相对电导率及丙二醛含量均呈上升趋势,而游离脯氨酸含量的变化则有显著差异。根据生理指标的变化可以看出,黄连木(Pistacia chinensis Bunge)和石楠(Photinia serrulata Lindl.)的耐水淹能力较弱,耐水淹时间仅为5至10 d;蓝果树(Nyssa sinensis Oliv.)、薄壳山核桃〔Carya illinoensis(Wangenh.)Koch〕、榉树(Zelkova schneideriana Hand.-Mazz.)和一球悬铃木(Platanus occidentalis L.)具有一定的耐水淹能力,耐水淹时间约为25 d;乌桕〔Sapium sebiferum(L.) Roxb.〕和白蜡(Fraxinus chinensis Roxb.)的耐水淹能力较强,耐水淹时间超过45 d;墨西哥落羽杉(Taxodium macronatum Ten.)和花叶杞柳(Salixintegra‘Hakuro Nishiki’)的耐水淹能力最强,受水淹的60 d内无受害现象。     

Characterization of populations of rapid-cycling Brassica rapa L. selected for differential waterlogging tolerance

By challenging a heterogenous population of plants (rapid-cyclingBrassica rapa L.) with waterlogging stress, we selected plantswhich differed in their response to root zone hypoxia. Theseindividuals were placed into ‘tolerant’ and ‘sensitive’populations based on foliage colour after waterlogging and werethen mass-pollinated and re-selected over seven generationsto produce the stable populations described. To assess responsesto root zone hypoxia in the selected populations, plants weregrown for 1 week after germination under normal watering conditionsand then subjected to waterlogging stress for up to 8 d. Undercontrol conditions, no differences were found between the tolerantand sensitive populations in any of the parameters studied.Chlorophyll concentrations in the tolerant population were significantlygreater than the concentrations in the sensitive populationwhen plants had been waterlogged. A similar stress-specificdifference was found in root and shoot dry matter accrual. Assoil redox values (and hence, available oxygen) decreased, anincrease in soluble carbohydrates and starch occurred in theleaves of waterlogged plants. Changes in soluble carbohydrateswere noted as early as 12 h after waterlogging in the sensitiveplants, and starch concentrations were significantly higherfor this population 24 h after waterlogging. Under waterloggedconditions, activities of alcohol dehydrogenase (ADH) and pyruvatedecarboxylase (PDC) increased, phosphoglucomutase and malatedehydrogenase decreased, and malic enzyme and glucose 6-phosphatedehydrogenase did not change. The sensitive population exceededthe tolerant population in activities of ADH and PDC after 18and 48 h of waterlogging, respectively. The results demonstratethat stress-specific differences in population responses towaterlogging can be achieved through recurrent selection. Key words: Waterlogging, carbohydrates, selection, hypoxia, Brassica rapa     

Interactive effects of salinity and water depth on the growth of Melaleuca ericifolia Sm. (Swamp paperbark) seedlings

Melaleuca ericifolia Sm. (Swamp paperbark) is a common tree species in freshwater and brackish wetlands in southern and eastern Australia. The survival of this species in many wetlands is now threatened by increased salinity and inappropriate water regimes. We examined the response of 5-month-old M. ericifolia seedlings to three water depths (exposed, waterlogged and submerged) at three salinities (2, 49 and 60 dS m⁻¹). Increasing water depth at the lowest salinity did not affect survival, but strongly inhibited seedling growth. Total biomass, leaf area and maximum root length were highest in exposed plants, intermediate in waterlogged plants and lowest in submerged plants. Although completely submerged plants survived for 10 weeks at the lowest salinity, they demonstrated negative growth rates and were unable to extend their shoots above the water surface. At the higher salinities, M. ericifolia seedlings were intolerant of waterlogging and submergence: all plants died after 9 weeks at 60 dS m⁻¹. Soil salinities increased over time, and by Week 10, exceeded external water column salinities in both the exposed and waterlogged treatments. In exposed sediment, ∼90% of plants survived for 10 weeks at 60 dS m⁻¹ even though soil salinities reached ∼76 dS m⁻¹. No mortality occurred in the exposed plants at 49 dS m⁻¹, and small but positive relative growth rates were recorded at Week 10. We conclude that at low salinities M. ericifolia seedlings are highly tolerant of sediment waterlogging, but are unlikely to tolerate prolonged submergence. However, at the higher salinities, M. ericifolia seedlings are intolerant of waterlogging and submergence and died rapidly after 5 weeks exposure to this combination of environmental stressors. This research demonstrates that salinity may restrict the range of water regimes tolerated by aquatic plants.     

Salinity tolerance and ecological aspects of some microfungi from saline and non-saline soils in Wyoming

The salt tolerance ofActinomucor harzii andPenicillium lilacinum both garden soil dominants and twoCephalosporium species from saline soils in Wyoming was investigated. BothCephalosporium species exhibited growth maxima, in culture, at salt concentrations approximating those of the habitat from which they were obtained.P. lilacinum exhibited an ability to adjust, with time, to high MgSO₄ concentrations and is considered salt-tolerant.A. harzii was consistently salt-sensitive. The ecological significance of the investigation is discussed.     

Physiology and biochemistry of waterlogging tolerance in plants

Waterlogging is a serious problem, which affects crop growth and yield in low lying rainfed areas. The main cause of damage under waterlogging is oxygen deprivation, which affect nutrient and water uptake, so the plants show wilting even when surrounded by excess of water. Lack of oxygen shift the energy metabolism from aerobic mode to anaerobic mode. Plants adapted to waterlogged conditions, have mechanisms to cope with this stress such as aerenchyma formation, increased availability of soluble sugars, greater activity of glycolytic pathway and fermentation enzymes and involvement of antioxidant defence mechanism to cope with the post hypoxia/anoxia oxidative stress. Gaseous plant hormone ethylene plays an important role in modifying plant response to oxygen deficiency. It has been reported to induce genes of enzymes associated with aerenchyma formation, glycolysis and fermentation pathway. Besides, nonsymbiotic-haemoglobins and nitric oxide have also been suggested as an alternative to fermentation for maintaining lower redox potential (low NADH/NAD ratio), and thereby playing an important role in anaerobic stress tolerance and signaling.     

Influence of waterlogging on some anti-oxidative enzymatic activities of two barley genotypes differing in anoxia tolerance

The experiment was conducted to investigate the formation of oxidative stress and the development of anti-oxidative enzymes in two barley genotypes differing in anoxia tolerance. Waterlogging led to significant reduction in root and shoot weight, green leaf area and tillers per plant, but tolerant Xiumai 3 was much less reduced than sensitive Gerdner. Malondialdehyde (MDA) content, an indicator of membrane lipid peroxidation, significantly increased in Gerdner when the plants were subjected to waterlogging, but remained little changed in Xiumai 3. Superoxide dismutase (SOD) activity was increased with waterlogging treatment and the sensitive cultivar had higher activity than the tolerant one during the experimental duration. At early stage of waterlogging treatment, both peroxidase (POD) and catalase (CAT) activities significantly increased in Xuimai 3, while obviously decreased in Gerdner. Moreover, both cultivars showed substantial increase in both POD and CAT with the progress of waterlogging exposure. Glutathione reductase (GR) activity was increased in both tolerant- and sensitive cultivars under waterlogging. It may be assumed from the current results that SOD activity appears to be not a constraining factor limiting the scavenging of ROS, and it is the change of POD and CAT activity under waterlogging that determine the status of oxidative stress. The difference between genotypes in waterlogging tolerance could be distinguished from the changed patterns of these enzymatic activities.     

Genetic variation for waterlogging tolerance in the Triticeae and the chromosomal location of genes conferring waterlogging tolerance in Thinopyrum elongatum.

A number of Triticeae species were tested for tiller production, shoot dry matter production, and root penetration in waterlogged soil, and Thinopyrum elongatum and Elytrigia repens were shown to have better tolerance than wheat using these criteria. Tests of a number of wheat-alien amphiploids showed that there was at least partial expression of this exotic genetic variation in a wheat genetic background. The presence of chromosomes 2E and 4E of Th. elongatum was associated with a positive effect on root growth in waterlogged conditions. The positive effect of the 4E chromosome addition was mimicked by tetrasomic lines carrying extra doses of wheat homoeologues 4B and 4D, and it was concluded that the beneficial effect contributed by the presence of 4E was probably due to an increased dosage of group 4 chromosomes. However, the positive effect of adding chromosome 2E to wheat could not be reproduced by added doses of chromosomes 2A, 2B, or 2D, suggesting that this alien chromosome carries gene(s) for tolerance not present on its wheat homoeologues. This gene(s) was further located to the long arm of chromosome 2E by testing ditelosomic addition lines.     

不同株型芝麻种质湿害后产量性状研究及耐湿性评价

于盛花期对66份种质进行湿害处理,结果表明:湿害对单秆型和分枝型种质的产量性状影响差异明显,对单秆型芝麻产量性状的影响(湿害指数值)大小依次为单株种子干重(69.18%)蒴果数(67.48%)有效果节数(49.10%)有效果轴长度(45.69%)株高(16.40%),对分枝性芝麻的影响依次为分枝有效果节数(65.96%)分枝蒴果数(64.73%)总蒴果数(52.01%)单株种子干重(49.92%)主茎蒴果数(41.66%)主茎有效果轴长度(37.57%)有效分枝数(34.21%)主茎有效果节数(20.12%)株高(15.43%);湿害对三蒴型芝麻的侧位蒴果影响较大,对单秆三蒴型芝麻的影响为侧位蒴果数(92.25%)中位蒴果数(50.25%),对分枝三蒴型芝麻的影响为分枝侧位蒴果数(92.86%)主茎侧位蒴果数(69.14%)分枝中位蒴果数(44.17%)主茎中位蒴果数(32.97%)。根据相对湿害产量可以将供试种质聚为耐湿与不耐湿二大类,不耐湿类型种质61份,占92.42%;耐湿类型种质5份,占7.58%,为竹山白芝麻、西平二郎花、阜南芝麻、嘉兴紧口黑和麻城黑芝麻,可作为耐湿种质加以利用。     

Salinity tolerance of Great Lakes invaders

1. The Laurentian Great Lakes are among the most invaded freshwater ecosystems in the world. Historically, the major vector for the introduction of non‐indigenous species (NIS) has been the release of contaminated ballast water via transoceanic ships. Despite regulations implemented in 1993, requiring vessels carrying fresh ballast water to exchange this water with saline ocean water, new reports of invasions have continued. 2. NIS often have a wide environmental tolerance allowing them to adapt to and invade a variety of habitats. It has been hypothesized that NIS with broad salinity tolerance may be able to survive ballast water exchange (BWE) and continue to pose an invasion risk to the Great Lakes. 3. We tested the short‐term salinity tolerance of eight recent invaders to the Great Lakes, specifically three cladocera (Bosmina coregoni, Bythotrephes longimanus, Cercopagis pengoi), two molluscs (Dreissena polymorpha, Dreissena rostriformis bugensis), and one species each of the families Gammaridae, Mysidae and Gobidae (Echinogammarus ischnus, Hemimysis anomala, Neogobius melanostomus) to determine if they could have survived salinities associated with BWE. 4. Overall, short‐term exposure to highly saline water dramatically reduced survival of all species. Two different methods of BWE tested, simultaneous and sequential, were equally effective in reducing survival. Species that survived the longest in highly saline water either possess behavioural characteristics that reduce exposure to adverse environments (valve closure; both Dreissena species) or are reported to have some degree of salinity tolerance in their native region (Echinogammarus). Given that exposure in our trials lasted a maximum of 48 h, and that species in ballast tanks would typically be exposed to saline water for c. 5 days, it appears that BWE is an effective method to reduce the survival of these NIS. These results provide impetus for tightening policy and monitoring of BWE, in particular for ships entering the Great Lakes from freshwater ports.     

三种冬青属树种的耐涝性和耐旱性评价

通过致死性干旱和致死性水涝处理,用生理生态方法,对冬青(Ilexchinensis)、绿冬青(I.viridis)和无刺枸骨(I.cornatavar.fortunei)进行抗逆性研究。耐涝性结果表明随淹水时间延长,3种受淹冬青体内的游离脯氨酸和丙二醛含量增加,净光合速率下降;比较而言,绿冬青上述受淹反应出现早,无刺枸骨出现迟,而冬青介于二者之间;绿冬青耐涝约1周,无刺枸骨耐涝2周以上,冬青耐涝介于二者之间,在江南水乡推广利用,耐涝方面不会成为限制因素。耐旱结果表明随干旱的逐渐加重,3种冬青体内的游离脯氨酸含量呈上升趋势,比较而言,绿冬青上升的峰值出现早,冬青和无刺枸骨的上升峰值出现迟;绿冬青耐旱约15d,无刺枸骨耐旱约25d,冬青介于二者之间。3种冬青均有一定的抗逆性,其中无刺枸骨对水胁迫的适应能力最强,冬青次之,而绿冬青相对较弱。     

Salinity tolerance of Saprolegnia parasitica coker

Experiments on two strains ofS. parasitica have shown that this species together with other species ofSaprolegnia have a high tolerance to salinity when vegetative growth alone is considered. The effect of temperature and salinity on asexual sporulation shows that at temperatures of up to 20°C good sporulation occurs in salinities of 3.5%.. At temperatures above this, sporulation is repressed and gammae tend to be formed. Temperature appears to have a marked effect on the initial germination of zoospores, but after 12 hours this effect is minimized.

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Zusammenfassung Untersuchungen an zwei Stämmen vonS. parasitica haben gezeigt, daß diese Art, zusammen mit anderen Arten vonSaprolegnia, eine hohe Toleranz gegen Salinität hat, wenn das vegetative Wachstum allein in Betracht gezogen wird. Die Wirkung von Temperatur und Salinität an asexuellen Sporulation zeigt, daß bei Temperaturen bis zu 20°C eine gute Sporulation in einer Salinität von 3.5%. vorherrscht. Bei höheren Temperaturen wird Sporulation unterdrückt und bilden sich Gammae. Temperatur scheint eine bedeutende Wirkung an der initialen Germination von Zoosporen zu haben, jedoch ist diese Wirkung nach 12 Stunden minimal.

     

Root morphology is related to the phenotypic variation in waterlogging tolerance of two populations of Suaeda salsa under salinity

The effects of waterlogging and salinity on seedling emergence, seedling growth and ion accumulation in a euhalophyte Suaeda salsa in an intertidal zone and on saline inland soil were investigated. Seedlings of S. salsa from the intertidal zone emerged more rapidly than those of the inland population under both waterlogged and drained conditions. Waterlogging and salinity had no adverse effects on seedling emergence of S. salsa from the intertidal zone, but markedly inhibited this parameter in the inland population. Waterlogging did not affect the seedling survival, shoot dry mass, and shoot height in high salinity in S. salsa from the intertidal zone, while the opposite trend was shown in the inland population. The root dry mass was higher in S. salsa from the intertidal zone as compared to the inland population, in waterlogged treatments by 1.9, 1.3, and 1.5 times in 1, 200, and 600 mM NaCl, respectively, and in drained treatments by 1.8, 2.3, and 3.0 times in 1, 200, and 600 mM NaCl, respectively. Waterlogging increased Na⁺ and K⁺ concentrations in high salinity, but waterlogging had no effect on Cl^- concentration in shoots of S. salsa from the intertidal zone. In all NaCl treatments, waterlogging had no effect on concentrations of these ions in shoots of S. salsa from the saline inland site. In a field investigation, the fresh mass of shoots and roots were lower, whereas the root/shoot ratio was 1.5 times higher in S. salsa from the intertidal zone, compared with the inland population. These findings indicate that S. salsa population from the intertidal zone is more waterlogging tolerant than the inland population. S. salsa from the intertidal zone produced relatively more root biomass and this might help anchor plants against tidal action in the intertidal zone. The physiological and morphological characteristics may determine the natural distributions of the two S. salsa populations in their different saline environments.     

Salinity and drought tolerance of mannitol-accumulating transgenic tobacco

Tobacco plants (Nicotiana tabacum L.) were transformed with a mannitol-1-phosphate dehydrogenase gene resulting in mannitol accumulation. Experiments were conducted to determine whether mannitol provides salt and/or drought stress protection through osmotic adjustment. Non-stressed transgenic plants were 20–25% smaller than non-stressed, non-transformed (wild-type) plants in both salinity and drought experiments. However, salt stress reduced dry weight in wild-type plants by 44%, but did not reduce the dry weight of transgenic plants. Transgenic plants adjusted osmotically by 0.57 MPa, whereas wild-type plants did not adjust osmotically in response to salt stress. Calculations of solute contribution to osmotic adjustment showed that mannitol contributed only 0-003-0-004 MPa to the 0.2 MPa difference in full turgor osmotic potential (π_o) between salt-stressed transgenic and wild-type plants. Assuming a cytoplasmic location for mannitol and that the cytoplasm constituted 5% of the total water volume, mannitol accounted for only 30–40% of the change in π_o of the cytoplasm. Inositol, a naturally occurring polyol in tobacco, accumulated in response to salt stress in both transgenic and wild-type plants, and was 3-fold more abundant than mannitol in transgenic plants. Drought stress reduced the leaf relative water content, leaf expansion, and dry weight of transgenic and wild-type plants. However, π_o was not significantly reduced by drought stress in transgenic or wild-type plants, despite an increase in non-structural carbohydrates and mannitol in droughted plants. We conclude that (1) mannitol was a relatively minor osmolyte in transgenic tobacco, but may have indirectly enhanced osmotic adjustment and salt tolerance; (2) inositol cannot substitute for mannitol in this role; (3) slower growth of the transgenic plants, and not the presence of mannitol per se, may have been the cause of greater salt tolerance, and (4) mannitol accumulation was enhanced by drought stress but did not affect π_o or drought tolerance.     

Salinity tolerance of normal-fruited and cherry tomato cultivars

The salinity tolerances (NaCl) of 8 normal-fruited tomato cultivars (Lycopersicon esculentum Mill.) and 4 cherry tomato cultivars (L. esculentum var.cerasiforme) were determined by yield-substrate EC response curves, according to the Mass-Hoffman model, modified by van Genuchten and Hoffman (1984). The same model was used to determine the response curves of leaf dry-weight, stem dry-weight, and plant height against substrate EC and also between yield and leaf concentrations of Cl- and Na ions.According to the salinity-threshold (maximum EC-value without yield reduction) and slope (yield decrease per unit EC increase) parameters, determined from the yield-EC response curves, the cherry tomato cultivars were more salt-tolerant than the normal-fruited ones. However, on the basis of vegetative growth characters-EC response curves, cherry tomato cultivars and normal-fruited ones were similarly affected by NaCl.The ranking of the cultivars by their salinity tolerance, determined from the plots of yield vs. leaf concentrations of Cl- and Na ions, was the same as that evaluated from the yield vs. substrate EC plots.     

Effects of waterlogging on chickpeas II. Possible causes of decreased tolerance of waterlogging at flowering

Waterlogging tolerance of chickpeas was found, in earlier work, to decrease sharply at flowering. Three experiments were performed to attempt to explain the mechanisms involved in this response. In the first, a range of treatments was imposed to modify the plant's source/sink relationships, as carbohydrate supply and partitioning were considered possible determinants of waterlogging tolerance. Plants from which buds were removed showed the most rapid recovery after waterlogging. Defoliation immediately before waterlogging reduced the rate of recovery. Application of benzyladenine plus gibberellic acid prior to waterlogging delayed stomatal closure and leaf senescence, inhibited apical growth and stimulated axillary growth. The second experiment aimed to confirm the influence of bud removal and to determine whether waterlogging tolerance is correlated with carbohydrate supply. Treatments comprised two sowing times, ten days apart, and two bud treatments (retained and removed). Waterlogging was imposed when older plants had been flowering for seven days and younger plants were in bud. Waterlogging caused soluble sugars to accumulate in the lower stem, suggesting that a deficiency of assimilates did not contribute to waterlogging injury. Similarly, waterlogging increased nitrogen concentration in the stem, through mobilisation from senescing leaves. Bud removal enhanced leaf survival and reduced mortality rate after waterlogging; it also increased starch concentration in the lower stem, indicating that storage of assimilates decreased in flowering plants. However, across all treatments, starch concentration was not correlated with waterlogging tolerance. In the third experiment, the effect of the senescence-promoting factor ethylene on preflowering and flowering plants was assessed, using the ethylene-releasing agent ethephon. Ethephon reduced growth to a slightly greater extent when applied prior to flowering than at flowering. There was no evidence that inadequate supply of carbohydrates or nitrogen in the stem, or increased sensitivity to ethylene, contributed to waterlogging intolerance in flowering chickpea plants.