不同基因型大豆对难溶性磷胁迫的生理响应

阐明大豆适应难溶性磷胁迫的生理反应,对筛选和培育磷高效基因型大豆工作具有重要意义。采用砂培和水培试验研究了大豆利用难溶性磷源的基因型差异及其生理指标的变化。结果表明:难溶性磷处理下大豆植株磷浓度和含磷量都显著低于高磷处理(P<0.05),不同基因型大豆的磷浓度和含磷量表现出较大的差异。难溶性磷诱导下,大豆叶片酸性磷酸酶增加;在处理后期,叶片丙二醛(MDA)含量远高于高磷对照;Ca-P和Fe-P处理下,植株磷浓度与叶片酸性磷酸酶呈极显著负相关。     

不同磷素水平下大豆叶片超显微结构的观察

利用筛选获得的表现稳定的磷高效基因型和磷低效基因型大豆品种各4个为材料,在不同供磷水平条件下培养至盛花期,取大豆生长点以下第二片复叶中间叶进行超微结构观察。结果表明:无论磷高效还是磷低效基因型品种随着施磷量的增加,叶片上单位面积气孔数目、气孔大小以及气孔开度均有所提高。在低磷处理下,磷高效基因型品种的气孔大小小于磷低效基因型品种,但气孔开度大于磷低效基因型品种,磷高效基因型品种低磷处理及中磷处理的单个叶肉细胞内叶绿体数量显著高于磷低效基因型品种,而高磷处理单个叶肉细胞内叶绿体数量则显著低于磷低效基因型品种。磷低效基因型品种随着磷肥施入量的增加,叶绿体的数量有所增加,且叶绿体形态较规则。对于磷高效基因型品种而言,高量的磷肥对叶绿体可能有一定的毒害作用,叶绿体破坏较为严重。因此,针对不同磷效基因型大豆合理地施用磷肥能有效改善叶片气孔及叶绿体的超微结构,提高大豆叶片光合作用的执行功能。     

磷素处理对不同磷效率基因型大豆根系性状的影响

大豆的耐低磷能力与根系性状密切相关.以磷高效基因型大豆锦豆33和磷低效基因型大豆铁丰3号为试材,采用沙培的方法,设5个磷浓度,研究了不同生育时期磷效率基因型大豆的主根长、根冠比、根体积、根系活性和根系比表面积对磷素处理的反应.结果表明:不同生育时期磷效率基因型大豆根系性状对磷浓度的反应比较复杂.幼苗期,不同磷浓度处理下主根长度和根冠比磷高效基因型品种均显著高于磷低效基因型品种;在有些磷浓度处理下根体积、根系活力和根系比表面积等指标基因型间差异达到显著水平,指标值的大小随磷浓度的变化没有一致的规律性.分枝期,不同磷效率基因型品种间和不同磷浓度处理间主根长度都没有显著差异.开花期,不同磷浓度处理下主根长度和根冠比存在显著的基因型间差异,表现为磷高效品种显著大于磷低效品种.结荚期,根系活力和根体积在不同磷浓度处理下均表现出显著的基因型间差异.在各磷浓度下,磷高效品种的根系活力都显著大于磷低效品种的.在O.5、1.O、1.5和2 mmol·L-1的磷浓度下,磷高效品种的根体积显著大于磷低效品种.     

大豆耐低磷鉴定指标研究

选用8个磷营养利用效率有差异的不同基因型大豆品种,设计0,0.5,1.0,1.5,2.0 mmol·L-15种磷元素浓度进行全生育期水培试验,研究了磷对大豆主要农艺性状的影响.结果表明:不同磷营养水平对大豆株高、底荚高、分枝数和主茎节数的影响不显著,对单株荚数、单株粒数、单株产量及盛花期叶面积的影响极显著,对百粒重的影响显著.单株荚数、单株粒数、单株产量、盛花期叶面积、百粒重与磷水平显著相关,初步认为,这些受磷影响显著且与磷显著相关的性状可作为耐低磷鉴定的指标.     

低磷胁迫对大豆根系生长特性及分泌 H+和有机酸的影响

以不同基因型大豆nf37和冀黄13为材料,水培法研究大豆根系周围的酸化现象,并通过对大豆根干重、根冠比以及植株中磷含量的测定来探讨不同基因型大豆对枸溶性磷肥的利用效率。结果表明,低磷胁迫下,不同基因型大豆的根系均能主动向外界环境分泌H+;经HPLC分析得出,柠檬酸、草酸、酒石酸和苹果酸是主要分泌的有机酸;当向培养介质中添加枸溶性磷肥后,不同基因型大豆均可有效利用这一难溶性磷肥。无论是H+分泌量、有机酸分泌量还是对枸溶性磷肥的利用效率,耐低磷基因型大豆（nf37）都显著高于磷敏感基因型大豆（冀黄13）。表明,低磷胁迫均导致不同基因型大豆根系向介质中分泌H+和有机酸,同时还诱导大豆根系的加速生长,各项指标在耐低磷和磷敏感大豆基因型之间表现出显著差异,这可能是不同基因型大豆对枸溶性磷肥吸收、利用效率不同的原因。     

缺磷胁迫对花生磷酸酶活性的影响

通过水培试验，对不同磷处理的花生干物重及酸性磷酸酶（APA）活性变化进行比较研究。结果表明不同花生品种耐低磷能力存在差异，豫花七号和农大818相对生长量高，有较高的耐低磷能力。在不同磷处理下，根系分泌APA及叶片APA活性差异明显，缺磷处理高于供磷处理，品种间差异显著。     

大豆适应低磷胁迫的机理初探

通过营养液栽培试验研究大豆适应低磷胁迫的机理，试图找出供试大豆在水培条件下对低磷胁迫下的适应性与田间表现的关系，为快速选育磷高效品种提供具有参考价值的实验数据。结果表明：在水培条件下，大豆在磷效率方面存在着显著的基因型差异。在总体磷效率(以生物量为标准)方面和磷吸收效率(整株含磷量)方面，结果与田间试验表现基本一致。BX10和GD1属于磷高效对磷不敏感基因型，BD2属于磷低效对磷不敏感基因型，BX11和GD2属于磷低效对磷敏感基因型，BD1属于磷高效对磷敏感基因型，GD3和GD4表现不稳定。从磷的利用效率(单位磷所产生的生物量)来看，基因型间没有显著差异。说明即使在水培条件下，磷利用效率对大豆总体磷效率贡献也不大，大豆总体磷效率主要是由吸收效率决定的。与田间反应不同的是，水培条件下磷吸收效率高的基因型，具有较长的根长与较大的根表面积。说明在介质有效磷分布均匀的条件下，根形态性状对磷吸收效率起一定的作用。     

低磷和干旱胁迫对不同基因型大豆光合生理特性的影响

采用盆栽培养的方法,研究了缺磷和干旱对鼓粒期磷高效基因型大豆黑河27,磷中效基因型大豆黑农43和磷低效基因型大豆黑河29的净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Cs)、胞间CO2浓度(Ci)、气孔限制值(Ls)、水分利用率等光合生理性状的影响.结果表明:低磷和干旱胁迫降低了3个基因型大豆叶片的净光合速率、蒸腾速率、气孔导度和气孔限制值;相反,胞问CO2浓度呈卜升趋势,说明光合速率的降低受非气孔因素的限制;低磷和干旱胁迫处理降低了大豆叶面积、叶绿素含量,变化为磷低效基因型＞磷中效基因型＞磷高效基因型,说明缺磷和长期干旱能使大豆叶而积降低,叶绿素降解,减少了光合叶而积和光能吸收,影响光合作用.与磷低效大豆相比,磷高效大豆具有在干旱条件下对CO2的同化和水分利川能力上的优势.磷高效大豆在水分逆境下叶片能保持较高的光合速率并提高对水分的利用效率,显示其对干旱有较强的耐受性.     

缺磷胁迫条件下大豆根系有机酸的分泌特性

采用水培和砂培方法检测了缺磷胁迫条件下大豆不同生育时期根系有机酸的分泌总量和组分的变化,结果表明:不同磷处理埘大豆根系分泌有机酸有显著的影响,缺磷胁迫条件下,不论是有机酸总量还是各有机酸组分的含量均显著高于正常供磷水平,差异显著,表明缺磷胁迫是促进大豆根系分泌有机酸的一个重要原因;大豆根系有机酸的分泌随生育时期而变化,表现为先增加后降低,在花期达到分泌高峰;大豆根系分泌的有机酸各组分在水培和砂培条件下基本一致,主要以苹果酸、柠檬酸、草酸、酒石酸等为主,砂培条件下有机酸的分泌量为水培条件下的2-3倍.     

不同磷效率大豆干物质积累、光合生理特性及产量的研究

利用不同磷效率基因型大豆品种,采用盆栽控制磷供应量,探讨其同化物积累及光合生理特性与产量性状的差异。结果表明:磷高效品种在低高磷处理下,相对干物质量比较高,能达0.9左右,而磷低效品种多在0.6左右;在低磷处理下,磷高效品种的净光合速率Pn均大于高磷处理,磷低效品种则小于高磷处理;高磷处理使气孔导度Cond、胞间CO2浓度(C i)、蒸腾速率(Tr)增加;低磷处理加强大豆叶片水分利用率(WUE);磷高效品种低高磷处理下产量比在0.9左右,磷低效品种仅为0.62。因此,可以将低高磷下干物质量比和产量比作为筛选不同磷效率基因型大豆的指标。     

Comparative Assessment of the Efficacy of Various Nitrogen Fertilizers

Summary

The efficiency of N fertilizers is usually poor; often less than 50% of the applied N is taken up by the crop. This review focuses on various N fertilizers with respect to the significance of different N loss pathways, namely (i) ammonia volatilization, (ii) dinitrogen and nitrogen oxide emissions, and (iii) nitrate leaching. Further, the significance of biological N immobilization, ammonium fixation and, finally, the impact of nitrate vs. ammonium uptake on crop yield are also discussed. The reviewed literature shows that N fertilizers may differ markedly in their susceptibility to losses. There is, however, considerable scope to improve N efficiency of each N source by proper N management practices.     

Studies on natural repellents against potato tuber moth (Phthorimaea operculella Zeller) in country stores

Summary The effects of the leaves of five plant species, one from each of the generaAmbrosia, Anemone, Eupatorium, Eucalyptus andLantana, on potato tuber moth were investigated under indigenous storage conditions at the Central Potato Research Station, Shillong (1800 m above sea level). Their action was compared with that of a biological insecticide (spores ofBacillus thuringiensis), a chemical insecticide (carbaryl), and an untreated control. The data collected after six months storage on tuber damage, sprout damage and the rotting indicated that the leaves ofLantana aculeata provided most protection to the tubers, reducing damage from over 70% in the check to below 5%, and sprout damage from over 45% to below 3%. Next best wasEucalyptus globulus followed byB. thuringiensis. They may be used on tubers stored for table use or for seed as they had no adverse effect on germination or on the yield of a subsequent crop.     

Mineral composition of some traditional Mexican teas

Teas of plant origin traditionally consumed by the Mountain Pima of Chihuahua, Mexico, were analyzed for mineral nutritional content. Fe, Cu, Zn, Ca, and Mg composition was determined for native teas made from shoots ofTagetes lucida, T. filifolia, Elytraria imbricata, andHolodiscus dumosus, and from root xylem ofCeanothus depressus andPhaseolus ritensis. Native uses of these teas are also described.     

Novel food and non-food uses for sorghum and millets

Sorghum and millets have considerable potential in foods and beverages. As they are gluten-free they are suitable for coeliacs. Sorghum is also a potentially important source of nutraceuticals such antioxidant phenolics and cholesterol-lowering waxes. Cakes, cookies, pasta, a parboiled rice-like product and snack foods have been successfully produced from sorghum and, in some cases, millets. Wheat-free sorghum or millet bread remains the main challenge. Additives such as native and pre-gelatinised starches, hydrocolloids, fat, egg and rye pentosans improve bread quality. However, specific volumes are lower than those for wheat bread or gluten-free breads based on pure starches, and in many cases, breads tend to stale faster. Lager and stout beers with sorghum are brewed commercially. Sorghum's high-starch gelatinisation temperature and low beta-amylase activity remain problems with regard to complete substitution of barley malt with sorghum malt . The role of the sorghum endosperm matrix protein and cell wall components in limiting extract is a research focus. Brewing with millets is still at an experimental stage. Sorghum could be important for bioethanol and other bio-industrial products. Bioethanol research has focused on improving the economics of the process through cultivar selection, method development for low-quality grain and pre-processing to recover valuable by-products. Potential by-products such as the kafirin prolamin proteins and the pericarp wax have potential as bioplastic films and coatings for foods, primarily due to their hydrophobicity.     

In vitro antimicrobial activity of different accessions ofSolanum commersonii Dun. from Uruguay

Summary The in vitro antimicrobial activity of extracts from accessions ofSolanum commersonii Dun. collected in the south of Uruguay was investigated against five microorganisms including the pathogenRalstonia solanacearum. A total of 30 extracts corresponding to organic and aqueous extracts were studied. Interestingly, most of the positive results for growth inhibition were againstR. solanacearum. The extracts were also analyzed for the presence of glycoalkaloids and lectins. Six of the ten aqueous extracts showed lectin presence and a wide variation in the type and amounts of glycoalkaloids, was found. Results indicate that there is no clear relationship between the antimicrobial activity against the five microorganisms screened and the presence or amounts of lectins and glycoalkaloids, traditionally regarded as possible antimicrobial metabolites in theSolanum genus, which indicates the presence of as yet unidentified antimicrobial compounds.     

Extreme resistance to infection by potato virus X in genotypes of wild tuber-bearingSolanum species

Summary Clones derived from thirty-one different accessions (nineteen of Argentine origin) belonging to eightSolanum species were screened for resistance to infection by potato virus X strain cp (PVX cp) by mechanical inoculation of plantlets that had been micropropagated in vitro. Estimates of PVX multiplication obtained by enzyme linked immunosorbent assay and slot blot nucleic acid hybridization allowed the identification of resistant clones derived from five accessions belonging toS. commersonii S. oplocense, S. sparsipilum andS. tuberosum andigena. Resistant genotypes supported PVX concentrations 5 to 15 times smaller than did the susceptible control cultivar Spunta. Graft inoculation test confirmed the presence of extreme resistance similar to that conferred by the ‘immunity’ gene X¹ (also called RX_act).     

Cyanobacteria Secondary Metabolites as Biotechnological Ingredients in Natural Anti-Aging Cosmetics: Potential to Overcome Hyperpigmentation,Loss of Skin Density and UV Radiation-Deleterious Effects

The loss of density and elasticity, the appearance of wrinkles and hyperpigmentation are among the first noticeable signs of skin aging. Beyond UV radiation and oxidative stress, matrix metalloproteinases (MMPs) assume a preponderant role in the process, since their deregulation results in the degradation of most extracellular matrix components. In this survey, four cyanobacteria strains were explored for their capacity to produce secondary metabolites with biotechnological potential for use in anti-aging formulations. Leptolyngbya boryana LEGE 15486 and Cephalothrix lacustris LEGE 15493 from freshwater ecosystems, and Leptolyngbya cf. ectocarpi LEGE 11479 and Nodosilinea nodulosa LEGE 06104 from marine habitats were sequentially extracted with acetone and water, and extracts were analyzed for their toxicity in cell lines with key roles in the skin context (HaCAT, 3T3L1, and hCMEC). The non-toxic extracts were chemically characterized in terms of proteins, carotenoids, phenols, and chlorophyll a, and their anti-aging potential was explored through their ability to scavenge the physiological free radical superoxide anion radical (O₂^•−), to reduce the activity of the MMPs elastase and hyaluronidase, to inhibit tyrosinase and thus avoid melanin production, and to block UV-B radiation (sun protection factor, SPF). Leptolyngbya species stood out for anti-aging purposes: L. boryana LEGE 15486 presented a remarkable SPF of 19 (at 200 µg/mL), being among the best species regarding O₂^•− scavenging, (IC₅₀ = 99.50 µg/mL) and also being able to inhibit tyrosinase (IC₂₅ = 784 µg/mL), proving to be promising against UV-induced skin-aging; L. ectocarpi LEGE 11479 was more efficient in inhibiting MMPs (hyaluronidase, IC₅₀ = 863 µg/mL; elastase, IC₅₀ = 391 µg/mL), thus being the choice to retard dermal density loss. Principal component analysis (PCA) of the data allowed the grouping of extracts into three groups, according to their chemical composition; the correlation of carotenoids and chlorophyll a with MMPs activity (p < 0.01), O₂^•− scavenging with phenolic compounds (p < 0.01), and phycocyanin and allophycocyanin with SPF, pointing to these compounds in particular as responsible for UV-B blockage. This original survey explores, for the first time, the biotechnological potential of these cyanobacteria strains in the field of skin aging, demonstrating the promising, innovative, and multifactorial nature of these microorganisms.     

Marine Pharmacology in 2009–2011: Marine Compounds with Antibacterial,Antidiabetic, Antifungal,Anti-Inflammatory,Antiprotozoal, Antituberculosis,and Antiviral Activities; Affecting the Immune and Nervous Systems,and other Miscellaneous Mechanisms of Action ?

The peer-reviewed marine pharmacology literature from 2009 to 2011 is presented in this review, following the format used in the 1998–2008 reviews of this series. The pharmacology of structurally-characterized compounds isolated from marine animals, algae, fungi and bacteria is discussed in a comprehensive manner. Antibacterial, antifungal, antiprotozoal, antituberculosis, and antiviral pharmacological activities were reported for 102 marine natural products. Additionally, 60 marine compounds were observed to affect the immune and nervous system as well as possess antidiabetic and anti-inflammatory effects. Finally, 68 marine metabolites were shown to interact with a variety of receptors and molecular targets, and thus will probably contribute to multiple pharmacological classes upon further mechanism of action studies. Marine pharmacology during 2009–2011 remained a global enterprise, with researchers from 35 countries, and the United States, contributing to the preclinical pharmacology of 262 marine compounds which are part of the preclinical pharmaceutical pipeline. Continued pharmacological research with marine natural products will contribute to enhance the marine pharmaceutical clinical pipeline, which in 2013 consisted of 17 marine natural products, analogs or derivatives targeting a limited number of disease categories.