47份木薯资源对朱砂叶螨的抗性鉴定及其抗性机理的初步研究

以47份木薯资源为材料,通过田间螨害情况调查,评价并鉴定木薯品种的朱砂叶螨抗性级别,同时对其中8份不同抗性木薯品种的形态学特征和生理生化特性进行调查及检测,研究木薯对朱砂叶螨的抗性与植株外部形态、叶片营养及生理生化特性的关系。结果表明:47份资源共包含4种抗性级别,分别为R、MR、S和HS,抗性最高的品种为食用木薯品种SC9和ST-1;未发现木薯品种螨害指数与株高、分枝部位、分枝数、叶形、叶片质地、裂叶长、裂叶宽、叶厚等植株形态学特征及氢氰酸含量、单宁含量、粗蛋白含量、可溶性糖含量间的相关关系;螨害指数与SPAD值间呈显著负相关关系,相关系数为-0.741。木薯对朱砂叶螨的抗性可能是各营养成分和生理指标等影响因素综合作用的结果,或者是在某一个指标达到对朱砂叶螨取食性产生作用的临界点时,才会对抗性起决定作用。SPAD值可作为木薯的朱砂叶螨抗性鉴定指标之一。     

木薯种质对朱砂叶螨的抗性评价

在建立切实可行的木薯抗螨性评级标准的基础上,对国家木薯种质资源圃227份核心木薯种质进行抗朱砂叶螨的抗性评价,并探讨抗、感性稳定的8份木薯种质对朱砂叶螨生长发育与繁殖的影响。结果表明:227份被评价的核心木薯种质中对朱砂叶螨高抗的种质2份,抗性种质4份,中抗种质116份,感性种质87份,高感种质18份;抗性木薯种质对朱砂叶螨的发育与繁殖具有显著的影响,取食高抗种质C1115和缅甸种叶片后朱砂叶螨雌雄成螨均不能存活,与取食高感种质ZM9066、CM1210-10、瑞士F21和BRA900相比,取食抗性种质哥伦比亚4D和PII167后,朱砂叶螨的发育历期显著延长,平均每雌螨产卵量显著减少,后代卵的孵化率显著降低,雌、雄成螨寿命均显著缩短。本研究结果为深入开展木薯抗螨性机理、抗螨种质的挖掘及其利用研究提供了理论基础。     

拟小食螨瓢虫对木薯朱砂叶螨的行为反应与空间分布相关性

拟小食螨瓢虫对小薯上朱砂叶螨种群数量具有一定的控制作用.为研究利用拟小食螨瓢虫控制朱砂叶螨,在观察拟小食螨瓢虫成虫对朱砂叶螨成、若螨和卵的逐日捕食量基础上,测定拟小食螨瓢虫对不同密度朱砂叶螨+螨害木薯叶VS健康木薯叶的选择性,调查拟小食螨瓢虫和朱砂叶螨在木薯上的空间分布相关性.结果表明:①拟小食螨瓢虫羽化后第3天对朱砂叶螨成、若螨和卵的捕食量达最大值,并趋于稳定.②当朱砂叶螨若螨和成螨密度为30头/叶及40头/叶时,拟小食螨瓢虫显著地趋向朱砂叶螨+螨害木薯叶复合体;(③当朱砂叶螨若螨和成螨在木薯上的分布数量分别为41.90头和32.60头时,拟小食螨瓢虫在木薯上的分布数壁达最大;(④天敌拟小食螨瓢虫对木薯朱砂叶螨的行为选择与二者在木薯上的空间分布之间存在正相关关系.本研究结果可为探讨拟小食螨瓢虫对木薯朱砂叶螨的选择机制,以便更好地利用其控制木薯朱砂叶螨为害提供科学依据.     

木薯叶片厚度、蜡质含量和气孔密度与抗朱砂叶螨的关系

为明确不同木薯品种的叶片组织结构与抗朱砂叶螨的关系,通过对木薯田间螨害情况的调查,计算出感、抗性稳定的感螨品种华南101、华南124和抗螨品种华南7号、华南13号的螨害指数,同时对叶片的相关物理性状进行测定,分析了叶片厚度、蜡质含量和气孔密度与木薯抗朱砂叶螨的关系。结果表明:4份木薯种质华南101、华南124、华南7号和华南13号的螨害指数依次为89.2%、65.8%、38.3%和0.8%;木薯叶片厚度与螨害指数呈显著负相关;气孔密度与螨害指数呈显著正相关;蜡质含量与螨害指数无显著相关性。上述结果为深入探究木薯抗螨机制提供了初步的理论基础。     

朱砂叶螨为害前后抗、感木薯品种叶组织中无色花青素还原酶活性差异分析

为了解木薯单宁酸合成关键酶无色花青素还原酶(leucoanthocyanidin reductase,LAR)在木薯抗螨中的功能与作用,本研究分析朱砂叶螨为害前后抗、感木薯品种不同叶龄组织LAR酶活性变化差异。结果表明:朱砂叶螨为害1、8 d时,高感木薯品种BRA900的未展开叶、展开幼嫩叶、顶芽下第3叶、中下部叶片的LAR酶活性分别为螨害前的1.38倍和1.44倍、1.33倍和1.48倍、1.42倍和1.43倍、0.82倍和0.50倍,除了中下部叶片螨害8 d的LAR酶活性显著降低外,其余叶片LAR酶活性在螨害前后均无显著差异(p<0.05);朱砂叶螨为害1、8 d时,高抗木薯品种C1115的未展开叶、展开幼嫩叶、顶芽下第3叶、中下部叶片的LAR酶活性则分别比螨害前显著提高2.13倍和2.41倍、2.02倍和2.09倍、2.02倍和2.04倍、2.01倍和2.03倍(p<0.05)。上述结果为阐明LAR酶活性显著提高与木薯品种抗螨能力的相关性及田间朱砂叶螨主要为害木薯中下部叶片提供了初步证据。      

木薯害虫普查及其安全性评估

为适应中国木薯产业的可持续发展需要,于2008～2009年间对木薯害虫、害螨在中国华南地区的分布、危害进行普查,并对2种国家检疫性毁灭性害虫、害螨进行了风险评估和5种主要害虫、害螨对木薯产业及本地生态经济的影响进行了分析。结果表明,海南、广西、广东共查获木薯害虫、害螨36种,其中害虫33种,害螨3种,并在国内首次发现木薯单爪螨和螺旋粉虱危害木薯,朱砂叶螨、蔗根锯天牛、白蛴螬在国内木薯种植区大面积严重发生与危害;木薯单爪螨、螺旋粉虱对木薯均属于高度危险有害生物;目前,木薯害虫、害螨已成为中国热区木薯产业能否可持续发展的重要限制因子之一,对木薯产业及本地生态经济的潜在影响与威胁十分严重。     

朱砂叶螨为害对木薯光合特性的影响

为了探讨朱砂叶螨(Tetranychus cinnabarinus Boisduval)为害损失理论基础,从叶绿素含量与光合特性相关的保护酶活性2个层次探讨朱砂叶螨为害对木薯光合特性的影响,以期为深入开展木薯螨害损失机理和及时监测与防控提供理论依据.结果表明:朱砂叶螨为害显著降低木薯叶片的叶绿素含量,但对不同的光合特性保护酶活性的影响不同.木薯叶片多酚氧化酶(PPO)、过氧化物酶(POD)和过氧化氢酶(CAT)的活性随着为害程度(每叶接螨数量)的增加和为害时间的延长呈显著上升趋势,但当每叶接45、55头朱砂叶螨时,其活性随着为害程度(每叶接螨数量)的增加和为害时间的延长先显著上升后显著下降;朱砂叶螨为害显著降低了木薯叶片抗坏血酸过氧化物酶(AsA-POD)和酯酶(α-NA EST/B-NA EST)的活性,但对木薯叶片超氧化物歧化酶(SOD)活性无显著影响.上述结果为及时有效防控朱砂叶螨的发生、为害及为害损失机理的深入探讨奠定了基础.     

保护酶CAT在木薯种质抗螨中的功能初步研究

为验证保护酶CAT在木薯抗螨中的功能,测定分析了朱砂叶螨取食抗、感螨木薯种质后,CAT的表达量和酶活分别在木薯和朱砂叶螨中的变化情况。结果表明,一方面,朱砂叶螨取食1 d和8 d后,感螨木薯种质BRA900体内Me CAT1的表达量和CAT总酶活仅分别较为害前提高1.11倍、1.24倍和1.06倍、1.15倍,而在抗螨木薯种质C1115体内则分别较为害前提高2.75倍、2.62倍和2.36倍、2.38倍,均显著高于感螨木薯水平。另一方面,朱砂叶螨取食感螨种质BRA900 1 d和8 d后,保护酶Tc CAT的基因表达量和CAT酶活分别是为害前的1.13倍、0.98倍和1.02倍、0.99倍,而取食抗螨木薯种质C1115 1 d和8 d后分别降低至为害前的0.57倍、0.61倍和0.52倍、0.61倍,均显著低于取食感螨木薯水平。以上结果初步证实了保护酶CAT在木薯中被诱导能够缓解朱砂叶螨造成的氧化损伤,在朱砂叶螨中被抑制不利于取食为害,从而形成木薯抗螨性的功能。本研究为将CAT作为基因资源应用于抗螨木薯种质创制提供了理论基础。     

朱砂叶螨转录因子TcNrf2对抗氧化酶基因表达的调控功能初步研究

转录因子Nrf2对模式生物抗氧化酶的调控起关键作用,但迄今为止尚未见Nrf2具有对害螨抗氧化酶调控功能相关报道。本研究将模式生物研究中已知的Nrf2基因抑制剂、激活剂处理朱砂叶螨,通过抑制、激活其转录因子TcNrf2的表达,研究其对下游调控的抗氧化酶基因TcSOD和TcCAT表达的影响。结果表明,采用抑制剂护鸦胆子苦醇处理时,朱砂叶螨取食抗、感木薯品种1、4、8d后,TcNrf2、TcSOD和TcCAT的基因表达量均显著降低,而采用抑制剂视黄酸处理时上述基因表达不受影响;采用激活剂特丁基对苯二酚和二噻环戊二烯硫酮分别处理后,朱砂叶螨TcNrf2、TcSOD和TcCAT的基因表达量均显著提高,说明TcNrf2及其调控的TcSOD和TcCAT基因表达量变化趋势具有一致性。本研究从分子水平直接证明TcNrf2基因在木薯抗螨中具有重要作用,为木薯抗螨分子机理研究奠定理论基础。     

基于生氰糖苷降解途径基因表达特性的木薯品种对二斑叶螨的抗性机制初探

为初步探究生氰糖苷降解途径2个基因α-HNL和β-glu在木薯品种对二斑叶螨抗性中的作用,本研究以抗螨木薯品种‘C1115’‘缅甸’‘SC9’和感螨木薯品种‘SC205’‘面包’‘BRA900’为材料,分析木薯生氰糖苷降解途径基因及其编码的生化酶在二斑叶螨取食木薯品种不同部位叶片（上部、中部和下部）不同时间后（1、4 d）的表达量及酶活性的变化情况。结果表明,α-HNL在感螨木薯品种上部和中部叶片中的表达量随螨害时间的延长而显著降低;在抗螨木薯品种的不同部位叶片中,α-HNL的表达量均随螨害时间的延长而显著升高,并且以中部和下部叶片的升高趋势更为显著。β-glu在抗、感螨木薯品种不同部位叶片中的表达量均很低,难以比较该基因的表达量在不同木薯品种、不同部位叶片受螨害后的变化情况,但在能检测到的少量样品当中,抗螨木薯品种的占比也多于感螨木薯品种。进一步进行酶活性分析结果表明,抗螨木薯品种受螨害后,随着时间的延长,降解途径基因α-HNL编码的α-HNL酶活性呈逐渐升高或维持不变的趋势,并且以中部和下部叶片的升高趋势更为显著,而在感螨木薯品种中,随着螨害时间的延长,α-HNL酶活性则呈逐渐降低或先升高后降低的趋势;β-glu基因编码的β-GLU酶活性在不同木薯品种中均呈较低的水平,这可能与其对应编码的基因表达量低有关,但总体而言,降解途径2个基因编码的降解酶α-HNL和β-GLU在抗螨木薯不同叶片组织中的活性总体上也显著高于感螨木薯。本研究初步揭示了不同木薯品种受螨害不同时间后,生氰糖苷降解基因和酶可能与木薯对二斑叶螨的抗性有关。     

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.     

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.     

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.     

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.