Salt tolerance of barley (Hordeum vulgare L.) cultivars at the germination stage: Analysis of the response functions

Two models, initially proposed by Van Genuchten (1983) for evaluating salinity-yield response curves at the adult stage, were applied to study the salinity response of 24 barley cultivars at the germination stage. According to the calculated salinity threshold, EC_t (the solution electrical conductivity, EC, at which germination starts to decrease), and EC₅₀ (the solution EC at which germination is reduced by 50%) parameters, both models give similar results, although model 2, a sigmoid-form curve, fits the observed data slightly better than model 1, a piecewise response function. Also, the results suggest that, for model 1, EC_t seems to be the most reliable parameter for screening barley germplasm because it clearly discriminates the relative salt-tolerance of the studied cultivars and, furthermore, it basically determines their salinity response for the 100 to 50% germination interval. On the other hand, the model 1 s parameter — percent germination decrease per unit salinity increase bove EC_t—is less relevant because of its smaller variation interval and lack of correlation with EC₅₀, indicating that the salinity response of the studied cultivars for the 50% germination value is independent of this parameter.     

Effects of root-zone solutes on Eucalyptus camaldulensis and Eucalyptus bicostata seedlings: Responses to Na+, Mg2+ and Cl-

Specific-ion effects in salt-treated eucalypts were examined with two species known to differ in salt tolerance viz. E. camaldulensis (more tolerant) and E. bicostata (less tolerant). Sand-cultured plants were irrigated with different nutrient solutions designed to impose either osmotic stress (concentrated macronutrients with balanced cations and anions) or specific ion stress from either NaCl or MgCl₂, or from nutrient solutions rich in particular ions viz. Na⁺, Mg²⁺ and Cl^- (balancing counter ions were provided in all cases). Half-strength Hoagland nutrient solution served as control. All treatments were applied at osmotic pressures of approximately 0.52 MPa by appropriate concentrations of each solution. In general, salt-induced growth reductions were greater for E. camaldulensis than for E. bicostata, although E. camaldulensis showed strongest exclusion of Na⁺, Mg²⁺ and Cl^- from shoots. Application of NaCl and concentrated macronutrients resulted in similar growth reductions. E. bicostata seedlings exposed to high Cl^- concentrations in the presence of Mg²⁺ and concentrated cations suffered significantly more shoot and root reduction than those exposed to other salts. Treatment with solution rich in Cl^- resulted in extensive leaf damage, which suggested that Cl^- may have exerted a specific effect. No specific Na⁺ effect was observed for either species, even though shoot Na⁺ concentrations were considerably higher for E. bicostata than for E. camaldulensis. Root growth was considerably less for plants treated with Mg²⁺ salts and this effect was associated with low root Ca²⁺ concentrations.     

Genes and salt tolerance: bringing them together

Salinity tolerance comes from genes that limit the rate of salt uptake from the soil and the transport of salt throughout the plant, adjust the ionic and osmotic balance of cells in roots and shoots, and regulate leaf development and the onset of senescence. This review lists some candidate genes for salinity tolerance, and draws together hypotheses about the functions of these genes and the specific tissues in which they might operate. Little has been revealed by gene expression studies so far, perhaps because the studies are not tissue-specific, and because the treatments are often traumatic and unnatural. Suggestions are made to increase the value of molecular studies in identifying genes that are important for salinity tolerance.     

番茄品种资源芽苗期和幼苗期的耐盐性及耐盐指标评价

对芽苗期和幼苗期番茄耐盐鉴定指标进行检验,明确番茄芽苗期和幼苗期耐盐性的相关性,筛选耐盐的番茄品种资源,以便为耐盐育种和栽培提供材料和方法.试验采用不同浓度的NaCl水溶液人工模拟盐胁迫,以多项指标盐害系数隶属函数值和总隶属函数值为依据,比较了20个番茄品种资源芽苗期和幼苗期的耐盐性及两个时期耐盐性的相关性,并利用单一指标盐害系数隶属函数值和总隶属函数值进行了聚类分类.结果表明:芽苗期和幼苗期番茄耐盐性有所不同,耐盐和中等耐盐材料相同率为53.85%.进行番茄耐盐性筛选时可以把发芽势、发芽率、发芽指数、萌发活力指数、下胚轴长、地上鲜重作为芽苗期耐盐鉴定指标,把地上部鲜重、根鲜重、地上部干重、根干重、壮苗指数、根/冠比作为幼苗期耐盐鉴定指标.     

植物抗盐分子机制及作物遗传改良耐盐性的研究进展

盐胁迫是全球农业生产上的一个主要逆境因子。解析耐盐分子机制有助于培育耐盐能力提高的作物新品种。我们综述了植物对盐胁迫的感应及信号传导、主要Na^＋运输体、盐胁迫下的解毒途径以及耐盐途径中涉及到的表观遗传研究。此外,我们还讨论了利用遗传改良手段提高作物耐盐性的研究进展。     

野生大豆耐盐性研究进展

野生大豆对于拓宽大豆种质遗传基础和丰富大豆种质基因库具有重要意义.该文从野生大豆的资源概况及优良性状、耐盐机理和利用野生大豆提高栽培大豆耐盐性等三个方面,对近年来国内外有关野生大豆耐盐性的解剖结构、生理基础、分子生物学基础等方面的研究进展进行了系统综述,并提出野生大豆通过茎叶表皮上的"腺体"及对Na+和Cl-的排斥性,实现对盐渍环境的颉颃作用.较强的抗氧化能力、大豆异黄酮代谢和耐盐基因也是其适应盐渍环境的重要原因.今后应对野生大豆耐盐机理的遗传学基础进行深入研究,并通过种群保护以保障野生大豆的发掘鉴定和创新利用.     

Salt tolerance in the halophyte Suaeda maritima L. Dum.

Osmotic potentials and individual epidermal cell turgor pressures were measured in the leaves of seedlings of Suaeda maritima growing over a range of salinities. Leaf osmotic potentials were lower (more negative) the higher the salt concentration of the solution and were lowest in the youngest leaves and stem apices, producing a gradient of osmotic potential towards the apex of the plant. Epidermal cell turgor pressures were of the order of 0.25 to 0.3 MPa in the youngest leaves measured, decreasing to under 0.05 MPa for the oldest leaves. This pattern of turgor pressure was largely unaffected by external salinity. Calculation of leaf water potential indicated that the gradient between young leaves and the external medium was not altered by salinity, but with older leaves, however, this gradient diminished from being the same as that for young leaves in the absence of NaCl, to under 30% of this value at 400 mM NaCl. These results are discussed in relation to the growth response of S. maritima.     

Relations of sugar composition and δ13C in phloem sap to growth and physiological performance of Eucalyptus globulus (Labill)

We characterized differences in carbon isotopic content (δ¹³C) and sugar concentrations in phloem exudates from Eucalyptus globulus (Labill) plantations across a rainfall gradient in south‐western Australia. Phloem sap δ¹³C and sugar concentrations varied with season and annual rainfall. Annual bole growth was negatively related to phloem sap δ¹³C during summer, suggesting a water limitation, yet was positively related in winter. We conclude that when water is abundant, variations in carboxylation rates become significant to overall growth. Concentrations of sucrose in phloem sap varied across sites by up to 600 mm, and raffinose by 300 mm . These compounds play significant roles in maintaining osmotic balance and facilitating carbon movement into the phloem, and their relative abundances contribute strongly to overall δ¹³C of phloem sap. Taken together, the δ¹³C and concentrations of specific sugars in phloem sap provide significant insights to functions supporting growth at the tree, site and landscape scale.     

新疆胀果甘草幼苗耐盐性及对NaCl胁迫的离子响应

以盐碱荒漠草甸药用植物胀果甘草(Glycyrrhiza inflata)为材料, 采用水培法研究了盐处理(50、100、200、300 mmol·L^-1NaCl) 28天后幼苗株高、生物量、含水量、根粗、甘草酸含量和不同器官的离子含量及离子的选择吸收、运输能力, 并对丙二醛、脯氨酸含量进行测定, 以确定其耐盐范围及耐盐方式。结果表明, 低盐浓度对胀果甘草幼苗生长无显著影响, 只有较高盐浓度(≥200 mmol·L^-1 NaCl)使幼苗总生物量、株高、甘草酸含量显著降低; 根据耐盐系数与盐浓度的拟合方程, 确定适宜幼苗生长的盐浓度范围为0-278.17 mmol·L^-1。随盐浓度上升, 植株选择性吸收K⁺、Ca²⁺、Mg²⁺, 而抑制Na⁺进入体内, 幼苗对进入植株体内的Na⁺在不同盐浓度下采取了不同的分配策略, 低盐浓度下(0-100 mmol·L^-1), 植株体内Na⁺主要积累在根中, 避免了叶中Na⁺的过多积累, 其盐适应机制以耐盐方式为主; 高盐浓度下(≥200 mmol·L^-1 NaCl), Na⁺主要积累在下部叶, 并通过叶片脱落的方式带走体内的盐分, 其盐适应机制以避盐方式为主。盐胁迫下, 幼苗能促进K⁺而抑制Na⁺向上部叶的运输, 使上部叶拒Na喜K, 维持了较高的K⁺/Na⁺比值, 有利于幼苗生长; 同时, 地下根系能通过积累Ca²⁺、Mg²⁺和合成脯氨酸、甘草酸, 以提高渗透调节能力, 缓解Na⁺毒害, 使根的生长不受影响, 有利于保证幼苗在盐环境中吸收维持生长的必要养分, 这是胀果甘草幼苗具有较强耐盐性的原因。以上结果说明, 胀果甘草幼苗通过对盐离子的吸收和运输调控、离子区域化和渗透调节, 以耐盐和避盐两种方式适应盐碱荒漠环境。     

In vitro salt and thermal tolerance of fungal endophytes of Nicotiana spp. growing in arid regions of north-western Australia

Abstract

Endophytic fungal strains isolated from indigenous Nicotiana plants naturally growing in dry and hot regions of north-western Australia were characterised based on their tolerance to salinity and temperature. Sixty-eight fungal isolates were tested on eight levels (0.5 M, 1.0 M, 1.5 M, 2.0 M, 2.5 M, 3.0 M, 3.5 M and 4.0 M) of five different of salts solutions NaCl, KCl, MgCl₂, CaCl₂ and MgSO₄ and at various temperatures (25–50?°C). The salt adaptation test indicated that the fungal strains namely Aspergillus niger (E-202), A. ochraceous-A (E-134), Aurantiporus sp. (E-135), Cladosporium halotolerance (E-128), Pleurostomophora richardsiae (E-13) and Trichoderma sp. (E-185.1) were tolerant to higher concentrations of various salts. The most growth-limiting salt turned out to be MgCl₂ followed by the chaotrope CaCl₂. Responses to temperature tolerance revealed that most fungi tested could grow at 30?°C. About 50% all the fungi did not show any growth when the temperature was raised above 30?°C. When the temperature was raised up to 50?°C all the fungi failed to grow but the fungus Rasamsonia piperina (E-172). Endophyte strains identified could be promising candidates for future research in investigating the fungus–plant interactions and their roles in plant adaptation to inhospitable environments.     

Growth cost and ontogenetic expression patterns of defence in cyanogenic Eucalyptus spp.

Plant defences can incur allocation costs and such costs incurred early in ontogeny may result in opportunity costs with effects evident later in life. A unified understanding of the growth cost of defence requires the identification of plants with varying ontogenetic trajectories of preferably resource demanding defences and an appropriate measurement of the growth cost of these defences. To develop such tools, we first compared nitrogen-based chemical defence (cyanogenic glycosides) in juvenile and adult foliage of three species of Eucalyptus (Myrtaceae). We found marked differences between the species, with two having much lower concentrations of foliar cyanogenic glycosides in seedlings compared to adults. We next used seedlings of two species to measure the resource (nitrogen) and growth cost of deploying cyanogenic glycosides. We found evidence that for every 1.0 nitrogen invested in cyanogenic glycosides, 1.49 additional nitrogens were effectively added to the leaves. We also found that deployment of cyanogenic glycosides was associated with a reduction in net assimilation rate (NAR) at constant leaf nitrogen. We did not, however, detect an overall growth cost associated with cyanogenic glycoside deployment because the rise in leaf nitrogen associated with this deployment apparently counteracted the reduction in NAR.     

Plant growth and ion relations in lucerne (Medicago sativa L.) in response to the combined effects of NaCl and P

The combined effect of NaCl and P on the growth of lucerne was studied in two hydroponic greenhouse experiments. NaCl concentrations were identical in each experiment (0, 50 and 100 mM NaCl) while external P concentrations were low (viz. 0.002, 0.02 and 0.2 mM measured as 0.006, 0.026 and 0.2 mM, respectively) in one experiment and higher (0.5 and 5.0 mM) in the second. Plant biomass was reduced more by the low P levels than by high concentrations of NaCl. A significant NaCl^*P effect was found where external P concentrations were low (0.006–0.2 mM) but there was no difference in plant production between the two P concentrations of 0.5 and 5.0 mM. Shoot and root concentrations of Na and Cl increased significantly with increasing NaCl concentration in both experiments and there were some differences in the concentrations of these ions at different external P levels. At low P, NaCl had no significant effect on shoot concentrations of P; however, root P concentrations tended to decrease with increasing NaCl level. Increasing external P from 0.006 to 0.2 mM led to significant increases in P concentrations in both roots and shoots. At higher P, concentrations of P in both the shoots and the roots did not differ with external NaCl or P conditions. Our results illustrate the complex relationship that exists between NaCl and P at low P levels. We conclude that high or non-limiting concentrations of P (0.2 – 5.0 mM) do not affect lucerne's response to NaCl.     

Salt and drought tolerance of sugarcane under iso-osmotic salt and water stress: growth,osmolytes accumulation,and antioxidant defense

In order to discriminate between the ionic and osmotic components of salt stress, sugarcane (Saccharum officinarum L. cv. Co 86032) plants were treated with salt-NaCl or polyethylene glycol-PEG 8000 solutions (?0.7 MPa) for 15 days. Both the salt and PEG treatments significantly reduced leaf width, number of green leaves, and chlorophyll stability index. Osmotic adjustment (OA) indicated that both the stresses led to significant accumulation of osmolytes and sugars. Salt stressed plants appeared to use salt as an osmoticum while the PEG stressed plants showed an accumulation of sugars. Oxidative damage to membranes was not severe in plants subjected to salt or PEG stress. The salt stressed plants showed an increase in the activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX), while PEG stress led to an increase in SOD but not APX activity as compared to the control. Thus, results indicate that the iso-osmotic salt or PEG stress led to differential responses in plants especially with respect to growth, OA, and antioxidant enzyme activities.     

大豆耐盐相关QTLs鉴定和功能基因研究进展

大豆(Glycine max (L.) Merill)是重要的粮食作物和经济作物,盐胁迫能造成大豆产量的大幅度降低。本文综述了通过正向遗传学手段获得的大豆耐盐数量性状位点(Quantitative trait locus, QTL)以及通过反向遗传学方法获得的大豆耐盐功能基因方面的研究进展。目前,正向遗传学发掘基因主要有图位克隆(Map-based cloning)和全基因组关联分析(Genome-wide association study, GWAS)两种方案,其中通过图位克隆在大豆中已经获得了6个耐盐QTL位点并且定位了1个重要的耐盐基因;利用GWAS在大豆中获得了1个耐盐功能基因。利用反向遗传学在大豆中获得了大量的耐盐相关功能基因并在模式植物中验证了其功能,主要包括离子转运蛋白基因和转录因子基因。这些研究为揭示大豆耐盐分子机制以及通过分子标记辅助育种或转基因技术创制耐盐大豆奠定了基础。     

转抗盐基因中天杨新品种扦插育苗耐盐试验

利用滨海盐碱土配制营养基质,采用盆栽扦插的方法,对转抗盐基因(mtl-D基因)中天杨新品种的耐盐能力、生长表现和根系发育状况进行了对比试验研究。结果表明,随着土壤含盐量的增加,插穗存活率降低,生长量减少,仅2 g.kg-1盐度试验组生长正常,叶色浓绿,存活率一直保持在90%以上,4 g.kg-1以上盐度试验组均因盐害而陆续枯死;土壤盐害首先作用于皮部侧根,表现为新生皮部根褐变坏死,导致枝叶发黄、萎蔫,并逐渐干枯死亡;扦插育苗前期,转基因中天杨与对照的耐盐能力和生长表现并无明显差别,其原因可能与插穗中外源基因的表达过程有关。     

金藜麦耐盐性分析及营养评价

对我国沿海地区新收集种质资源金藜麦(Chenopodium quinoa Willd.)进行了耐盐性及营养品质评价。结果表明:金藜麦在对盐胁迫相对敏感的芽期和苗期表现出相对较高的耐盐性;子粒蛋白质含量为14.2%,蛋白营养价值优于牛奶以及小麦、水稻、玉米、大豆等作物;子粒中富含维生素B、E等以及钙、锰、铁、铜、锌等矿质元素,特别是钙含量高达190.16 mg/100g,是小米钙含量的35倍;且金藜麦子粒含有丰富的必需脂肪酸,如亚油酸(3.58 g/100g)和亚麻酸(0.44 g/100g),天然抗氧化剂维生素E含量为7.66 mg/100g。这些研究结果表明,新收集的金藜麦种质资源具有较高的营养价值和耐盐性,将为我国藜麦研究和种植提供重要的种质资源。     

Extraction of water from Eucalyptus trees for analysis of deuterium and oxygen-18: laboratory and field techniques

This study investigated a methodology for sampling and extracting water from Eucalyptus spp. for analysis of stable isotopes of water. Firstly, water of known isotopic composition was extracted from stems of seedlings of Eucalyptus spp. by azeotropic distillation using three solvents (hexane, toluene and kerosene) in laboratory and glasshouse experiments. Kerosene and toluene gave the most accurate extractions, with a small negative bias (～-2‰ for δ²H and ～-0.4‰ for δ¹⁸O) due to incomplete extraction. This bias was not evident in further experiments, using kerosene, where water was extracted from stems and roots that had been pre-treated in a manner that more closely reflected field conditions. Secondly, variation in δ²H in trees was investigated in the field to determine an accurate and convenient place for sampling. There was no significant difference in δ²H between water extracted from trunk sapwood and whole twigs, even twigs close to leaves, in samples taken from four Eucalyptus spp. at two field sites. The results mean that the most convenient part of the tree can be sampled. Also, there was little difference in δ²H between sapwood and heart-wood samples, although small increases (～ 2‰) in δ²H were observed in bark of trunks and twigs. Tree roots (15–25 mm diameter) had similar δ²H values to the surrounding soil in many cases, especially surface (<0.2 m depth) roots, rather than having δ²H values similar to twigs of the trees. These roots were absorbing water from surrounding soil, but not contributing significant quantities of water to the tree canopy. Thus, the δ²H of root water is not a good indicator of the isotopic composition of water in the upper parts of Eucalyptus trees.     

棉花萌发期和苗期耐盐性评价及耐盐指标筛选

于2010年在江苏南京农业大学人工气候室内进行砂培试验,采用不同浓度的NaCl水溶液模拟盐胁迫,以多项指标盐害系数隶属函数值和总隶属函数值为依据,比较了13个棉花品种萌发期和苗期的耐盐性,并进行聚类分析.结果表明:150mmol·L-1NaCl是进行棉花耐盐性鉴定的适宜盐浓度.棉花的耐盐性在生育期和品种间表现不同:中棉所44和中棉所177是在萌发期和苗期均表现稳定的耐盐品种,表现稳定但不耐盐品种有中棉所102、苏棉12号和泗棉3号,表现稳定且中等耐盐品种有中棉所103、德夏棉1号和美棉33B;发芽率、发芽势、发芽指数、活力指数和鲜质量的盐害系数可以作为棉花萌发期耐盐鉴定指标,株高、叶片伸展速率、地上部干质量、根系干质量、根系活力和净光合速率的盐害系数可以作为棉花苗期耐盐鉴定指标.     

Tolerance of Hybrid Poplar (Populus) Trees Irrigated with Varied Levels of Salt,Selenium, and Boron

Agricultural drainage waters and industrial effluents often consist of waste waters laden with salts, boron (B), selenium (Se), molybdenum (Mo), and other contaminants. However, increasing shortages of high-quality water in arid and semiarid regions and increasing demands to maintain the water quality in rivers, lakes, streams, and groundwater have made water reuse an imperative. Trees have been viewed as potential candidates for wastewater reuse because of their capacities for high evapotranspiration, high growth rates, and abilities to accumulate salts and specific ions in a marketable product that is not biologically hazardous. Clones of eight hybrid poplar (Populus spp.) crosses were tested for salt tolerance and ion uptake characteristics in a sand culture study in Riverside, CA. After hardwood cuttings were planted and established under nonsaline conditions, young saplings were treated with artificial waste waters containing different levels of salts, Se, and B. High salt concentrations reduced growth and led to leaf damage and shedding; however, Se and B had no detrimental effect on growth. Salinity affected Se and B accumulation patterns in leaves. A significant degree of genetic variation in salt tolerance was noted among the clones. The salinity at which dry weight was reduced ranged from about 3.3 to about 7.6 dS m^-1 depending on clone, and the relative decrease in dry weight yield with increasing salinity varied among clones and ranged from about 10 to 15% per dS m^-1. This would indicate that poplars, whereas certainly more salt tolerant than avocado trees, are significantly less salt tolerant than eucalyptus. Leaf C1 concentrations increased in relation to the C1 concentrations in the irrigation waters, but also were subject to clonal variation. Salt tolerance in poplar was generally related to C1 in the leaves and stems but was also influenced by growth and vigor characteristics, as well as the allometric relationships between leaves and stems that influenced the sinks in which ions could accumulate before reaching toxic levels.