植物激素在豆科植物根瘤形成和发育过程中的调控作用

豆科植物能够利用与根瘤菌形成的共生系统高效地固定氮素养分.根瘤形成过程包括表皮细胞中侵染线形成和皮层细胞根瘤原基形成2个阶段.豆科植物根瘤的形成和发育存在严格的调控机制,综述了多种激素正向(如细胞分裂素、生长素、赤霉素等)或负向(乙烯、逆境激素等)或协同调控根瘤的形成和发育的研究进展.并提出对激素调控结瘤机制的深入研究,将有助于提高豆科作物的产量,减缓氮肥过度使用造成的环境问题.     

大豆结瘤固氮的分子生理研究

有关豆科作物共生固氮的研究已有170 a的历史。而豆科结瘤固氮的分子生理研究,仅仅是最近30 a的事情。从影响大豆结瘤固氮的生理因子角度,评述了豆科作物的结瘤自动调控机制,进一步在分子水平上阐述了生长素、硝态氮、黄酮类等生理调控物质对大豆结瘤固氮的影响。生长素调节根瘤菌侵染位点和根瘤形成后的生长;可通过控制结瘤的角度来减少土壤硝态氮对大豆结瘤固氮能力的抑制;黄酮类物质在根瘤发育和结瘤基因诱导中起重要作用;乙烯抑制结瘤信号的前期过程,调整根瘤形成的空间分布。详细、系统地从作物-微生物之间关系出发,研究引起豆科作物根瘤形成和固氮系统的整体信号传导、蛋白和代谢过程,是未来大豆共生固氮分子生理研究应该注重的方向。     

大豆根瘤菌新菌种选育及其应用研究

一、菌株分离和筛选 1972年以来我们进行了大豆根瘤菌新菌种选育及其应用的研究。从栽培的大豆根瘤中能分离出在大豆上结瘤的根瘤菌,已被实践证实,据陈华癸(1965)等报导,从其他豆科植物根瘤中分离出的根瘤菌,也能在大豆上结瘤。1972—73年,我们在云南、湖北等地,先后采集栽培的大豆、花生和野生的豆科植物根瘤(选择健壮植株,着生主根的红色根瘤),在别列索娃培养基上,分离获得526个菌株。经水培法植物结瘤鉴定,从24种野生豆科植物根瘤中分离171个菌株,其中有19种植物157个菌株能在大豆上结瘤     

大豆根瘤菌结瘤作用统计方法的建立及其对接种效果的统计分析

利用发光大豆根瘤菌ＨＮ０１ＬＣ０２接种大豆黑农３９,通过对发光根瘤在大豆根系上的数量和位置分布进行分析,对根瘤菌的结瘤作用建立了一种新型统计方法,并用这种统计方法分析了不同接种技术对豆科植物结瘤作用和植物生长的影响。     

植物信号分子对大豆开花与结瘤的协同调控

大豆[Glycine max(L.)Merr.]是世界上重要的粮食和油料作物,其显著的生长特点是营养生长和生殖生长交错时间长,导致以结瘤为代表的营养生长和以开花为代表的生殖生长在物质和能量需求上存在激烈竞争。本文综述了蔗糖、植物激素以及miRNAs等植物信号分子对大豆开花和结瘤调控作用,将有助于理解大豆开花、结瘤的协同调控机制,以期对明确大豆生长发育规律、提高大豆产量提供理论支撑。     

植物激素及其对水稻植株发育调控的研究进展

随着我国科技力量的飞速发展,科学家们在激素受体基因分离鉴定、激素控制株型以及激素间的相互作用等方面取得了突破性进展,其中生长素(IAA)在协调体内外调节机制中起着不可或缺的作用;细胞分裂素(CTK)可以通过对细胞分裂与分化的调节而参与对水稻生长发育的调控;赤霉素作为植物生长的必需激素之一,调控植物生长发育的各个方面,如:种子萌发,下胚轴的伸长,叶片的生长和水稻开花时间等;脱落酸(ABA)同样也是一种重要的植物激素,受到生物胁迫和非生物胁迫的调控,在水稻对胁迫耐受性和抗性中发挥着重要作用;乙烯(ETH)则是一种多功能的植物激素,它在水稻生长发育和应对生物及非生物胁迫过程中起着重要作用。本文着重阐述了近几年植物激素在生理学研究方面的研究进展,提出了我国在植物激素研究领域的未来发展方向与趋势,同时也展望了植物激素研究对水稻重要农业性状改良的意义。     

AP2/ERF转录因子调控果实品质研究进展

乙烯是影响果实品质形成的重要植物激素,乙烯信号转导途径研究已经在不同果实中广泛开展,但其转录调控机制研究基本处于起步阶段。本文重点综述了AP2/ERF的果实品质转录调控研究进展,讨论了果实品质转录调控存在问题和研究趋势。     

磷和根瘤菌交互作用对大豆结瘤和生长的影响

为了阐明营养液中磷浓度和不同数量根瘤菌的交互作用对大豆结瘤和生长的影响,在营养液培养条件下,进行3种磷水平[P1-0、P2-4和P3-30(μmol P·I-1)]和3种根瘤菌浓度[RI-102、R2-103.5和R3-105(CFU·mL-1)]处理,培养大豆25 d,测定大豆生物量和根瘤性状指标.结果表明:在相同根瘤菌数量条件下,不同磷浓度对大豆总生物量的影响不大,对根冠比的影响较大营养液中接种的根瘤菌浓度越高,根瘤原基数量越夫,低磷明显抑制根瘤原基发育形成根瘤,进而减少了低磷处理大豆根瘤数量从P1到P3,R1恨瘤菌浓度处理根瘤原基形成根瘤的几率分别为:79%、86%和100%.营养液中磷浓度促进生物量向根瘤中分配,高磷处理相对根瘤生物量较高随着生育进程,大豆各组织器官含磷量逐渐降低,在所有取样时期含磷量均表现为根瘤>根>地上部;含氮量表现为根瘤>地上部>根.可见磷和根瘤菌对大豆生长和结瘤形成有交互作用.     

大豆的最佳氮肥施用时期研究

以３种不同基因型大豆品种为试材，研究大豆根瘤形成始期（二片复叶Ｖ２）和大豆生殖生长期间施用氮肥，对大豆生长，结瘤及产量的影响。试验结果表明，大豆营养生长阶段的最佳追肥时间为根瘤形成始期；面在豆生殖生长期间的最佳追肥时间为大豆开花期。     

花生结瘤起始因子基因鉴定及其对氮肥的响应

结瘤起始因子NIN(nodule inception)是最早发现的与植物结瘤相关的转录因子,是根瘤固氮遗传通路中重要组成成分,在结瘤早期发挥重要调节作用。为了研究花生NIN基因的功能,我们对栽培种花生中的NIN基因进行了鉴定,并利用生物信息学对该基因家族理化性质、进化关系、基因结构、表达模式等进行分析。结果表明栽培种花生中共有33个NIN基因,按亲缘关系可以分为4类;同一类的基因具有相同的基因结构和保守结构域;花生NIN基因在各个组织中表达量均较低,Arahy.I65W25和Arahy.V4BGUX在根和根瘤特异表达;在单作花生和花生//玉米间作条件下,部分NIN基因对氮肥的响应模式不同。本研究为深入研究花生NIN基因在根瘤形成和固氮遗传通路中的作用提供了理论基础。     

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.     

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.     

Recent Modifications of Chitosan for Adsorption Applications: A Critical and Systematic Review

Chitosan is considered to be one of the most promising and applicable materials in adsorption applications. The existence of amino and hydroxyl groups in its molecules contributes to many possible adsorption interactions between chitosan and pollutants (dyes, metals, ions, phenols, pharmaceuticals/drugs, pesticides, herbicides, etc.). These functional groups can help in establishing positions for modification. Based on the learning from previously published works in literature, researchers have achieved a modification of chitosan with a number of different functional groups. This work summarizes the published works of the last three years (2012–2014) regarding the modification reactions of chitosans (grafting, cross-linking, etc.) and their application to adsorption of different environmental pollutants (in liquid-phase).