玉米自交系资源对大斑病抗病性的鉴定

选用了国内外自交系230份玉米自交系进行了大斑病抗病性鉴定。其结果为高抗系、抗病系只占1%-11.7％感病系43．8％，高感系43．5％。     

玉米抗丝黑穗病的基因效应

利用2个抗玉米丝黑穗病自交系（齐319和Mo17）与2个感病系（E28和黄早四）,组配4个抗感杂交组合。2004年,对4个组合的亲本、F₁、F₂、BCR（F₁与抗病亲本回交1代）和BCS（F₁与感病亲本回交1代）6个世代群体分别在北京和黑龙江进行丝黑穗病的人工接种鉴定,采用世代平均值分析玉米抗丝黑穗病的遗传特点。研究表明,各杂交组合的抗病性均含有显著的加性效应,其中3个组合有显著的显性效应。不同杂交组合的抗病遗传模式表现不同,用感病亲本E28组配的2个组合（齐319×E28）和（Mo17×E28）的抗病性基本符合加性-显性遗传模型;而用另一个感病亲本黄早四组配的组合（齐319×黄早四）和（Mo17×黄早四）的抗病性存在明显的上位性效应。这说明玉米对丝黑穗病的抗性呈现较复杂的遗传模式。因此,在抗玉米丝黑穗病育种中既要重视对自交系抗病水平的鉴定,也要加强杂种F₁的合理组配及抗病性评估。     

64份玉米自交系抗粗缩病的遗传变异分析

在玉米粗缩病重发区,对64份玉米自交系进行了2年3种环境下的抗病性鉴定。以3种环境的平均病株率为指标,筛选出高抗自交系12份、抗病系17份、中抗系18份、感病系12份和高感系5份。采用70对SSR引物在64份自交系中检测出276个等位基因变异,平均多态性信息量0.57,结合系谱资料和育种实践可将供试系划为6个杂种优势亚群BSSS、PA、Lancaster、旅大红骨、四平头和PB。根据自交系对粗缩病的抗性反应,发现PB和四平头亚群的病株率较低（1.60%和4.95%）,为抗玉米粗缩病育种的重要种质类群。     

常用玉米自交系对大斑病抗性研究

本试验选用国内外180份玉米自交系为材料进行了犬斑病抗病性鉴定。结果表明，高抗系、抗病系只占5．5％、21．1％，感病系占26．7％，高感系占16．7％。     

玉米抗弯孢霉叶斑病鉴定及抗病材料利用

玉米弯孢霉叶斑病是我国北方玉米产区新发生的一种危害性很大的病害。１９９６年至１９９９年对玉米自交系进行了抗病鉴定，其中鉴定自交系９０４份，其结果高抗，抗病系只占１％￣１３．７％。中抗系占３２．７％，中感，感病系占２９．６％，高感系占１９．０％。     

玉米抗灰斑病基因的分子标记

玉米灰斑病是我国玉米生产中的重要病害,培育和种植抗病品种是防治此病的有效途径.1年内在3个灰斑病重发区选取64份我国常用玉米自交系进行了抗灰斑病鉴定,分别筛选出高抗、抗病和中抗自交系2份、15份和12份.采用集团混合分组分析法,分别以10个抗病和10个感病玉米自交系基因组DNA构建抗病基因池和感病基因池.从100对AFLP引物组合中筛选出54对在抗感基因池间呈多态性的引物,进一步在组建抗池和感池的20份自交系之间检测到8个多态性片段.通过片段的回收、克隆和测序,将其中的P51M38-100扩增片段转化为SCAR标记(SCAR-100).利用SCAR-100标记分析64份玉米自交系的基因型,结合田间抗病和感病表型进行相关分析,卡方测验表明SCAR-100标记与抗灰斑病显著相关.采用Mo17×黄早四群体(190个F2单株)和X178×B73群体(181个F8家系),结合已构建的SSR和AFLP标记连锁图谱,均将SCAR-100标记定位于第3染色体上,分别位于SSR标记umc1399-bnlg1754和umc1320-bnlg1754之间.开发抗病基因的分子标记可为分子标记辅助育种提供基础.     

玉米矮花叶病毒抗性资源鉴定的研究

利用人工接毒方法对 70份玉米种质资源进行了两年玉米矮花叶病毒B株系的抗性鉴定。依据病情指数 ( % )将抗病程度分为高抗、抗、中抗及感病 4个等级。试验筛选出高抗自交系 4份、高抗单交种 3个、抗病毒自交系 10份、抗病单交种 3个 ;中抗自交系 6份、中抗群体 3个。讨论了这些种质资源在我国抗玉米矮花叶病遗传及育种研究上的应用价值     

广西玉米自交系纹枯病抗病性鉴定

2003年秋至2005年夏连续2年对广西223份玉米自交系进行多年多重复的田间纹枯病抗病性鉴定。接种鉴定方法:将玉米纹枯病分离菌在大麦粒上扩繁,于玉米拔节期进行田间接种,采用国际玉米小麦改良中心(CIMMYT)的病害分级评定方法进行鉴定。结果表明:玉米自交系间的抗感性存在差异,同一自交系在同年度内春播与秋播鉴定中抗病性表现存在明显差异。在223份材料中未发现免疫类型,高抗自交系占所鉴定总数的1·3%、抗病的占14·4%、中抗水平占6·3%、感病占2·2%、高感占75·8%。     

用正反交及回交试验对黄瓜霜霉病的抗性遗传分析

本研究以黄瓜抗病自交系0023和黄瓜感病自交系112作为亲本,进行正反交试验和回交试验,分析正交F_1(0023×112)、反交F_1(112×0023)、正交F_2(0023×112)、反交F_2(112×0023),以及2个回交群体BC1(0023×112)×0023和BC1(0023×112)×112的黄瓜成株期间霜霉病田间自然发病的病情指数,分析黄瓜霜霉病的感、抗性状的遗传表现。试验结果表明黄瓜霜霉病的遗传属于细胞核遗传,受一对基因所控制,表现为不完全显性,其中感病性状为显性性状,抗病性状为隐性性状。因此,在进行黄瓜的抗霜霉病育种时应选择高抗品种作为亲本,且以早期选择为主。     

东北地区玉米骨干自交系对瘤黑粉病抗性的研究

采用人工接种的方法对东北地区常用骨干自交系对玉米瘤黑粉病的抗性进行了初步研究.结果表明,在供试的21个自交系中,沈139、沈137、沈151、丹340、84-7、C 8605-2、543、昌7-2和408-3表现为高抗;沈152表现为抗病;沈135、330、旅9宽、598、丹599、K 12和营851表现为中抗;Lx9801、Mo 17和A 801为感病;910为高感.     

Biological Activity and Quantification of Suspected Allelochemicals from Alfalfa Plant Parts

Autotoxicity restricts reseeding of alfalfa (Medicago sativa L.) after alfalfa until autotoxic chemical(s) breaks down or is dispersed into external environments. A series of aqueous extracts from leaves, stems, roots and seeds of alfalfa ‘Vernal’ were bioassayed against alfalfa seedlings of the same cultivar to determine their autotoxicity. The highest inhibition was found in the extracts from the leaves. Extracts at 40 g dry tissue l^?1 from alfalfa leaves were 15.4, 17.5 and 28.7 times more toxic to alfalfa root growth than were those from roots, stems and seeds, respectively. A high‐performance liquid chromatography (HPLC) analysis with nine standard compounds showed that the concentrations and compositions of allelopathic compounds depended on the plant parts. In leaf extracts that showed the most inhibitory effect on root growth, the highest amounts of allelochemicals were detected. Among nine phenolic compounds assayed for their phytotoxicity on root growth of alfalfa, coumarin, trans‐cinnamic acid and o‐coumaric acid at 10^?3 m were most inhibitory. The type and amount of causative allelochemicals found in alfalfa plant parts were highly correlated with the results of the bioassay, indicating that the autotoxic effects of alfalfa plant parts significantly differed.     

Changes in Seed Yield and Quality with Maturity in Onion (Allium cepa L., cv. 'Early Cream Gold')

Development of onion (Allium cepa L., cv. ‘Early Cream Gold’) seed under cool climate conditions in Tasmania, Australia occurred over a longer duration than previously reported, but similar patterns of change in yield components were recorded. In contrast to previous studies, umbel moisture content declined from 85 to 67 % over 57 days while seed moisture content decreased from 85 to 31 %. Seed yield continued to increase over the duration of crop development, with increasing seed weight compensating for seed loss resulting from capsule dehiscence in the later stages of maturation. Germination percentage was high and did not vary significantly from 53 to 77 days after full bloom (DAF), but mean germination time declined and uniformity of germination increased significantly over the same time period. The percentage abnormal seedlings declined with later harvest date, resulting in highest seed quality at 77 DAF. The results of this study suggest that the decision to harvest cool climate onion seed crops before capsule dehiscence will result in a loss of potential seed yield and quality.     

Location of a high-lysine gene and the DDT-resistance gene on barley chromosome 7

Summary The high-lysine gene in Risø mutant 1508 conditions an increased lysine content in the endosperm via a changed protein composition, a decreased seed size, and several other characters of the seed. The designation lys3a, lys3b, and lys3c, is proposed for the allelic high-lysine genes in three Risø mutants, nos 1508, 18, and 19. Linkage studies with translocations locate the lys3 locus in the centromere region of chromosome 7. A linkage study involving the loci lys3 and ddt (resistance to DDT) together with the marker loci fs (fragile stem), s (short rachilla hairs), and r (smooth awn) show that the order of the five loci on chromosome 7 from the long to the short chromosome arm is r, s, fs, lys3, ddt. The distance from locus r to locus ddt is about 100 centimorgans.     

Simultaneous Determination of Four Phenolic Acids in Radix Salviae Miltiorrhizae Formula Granules by QAMS

[Objectives]This study aimed to establish a QAMS(quantitative analysis of multi-components by single-marker)method for simultaneous determination of four phenol...     

Pollen and pollination experiments. III. The viability of apple and pear pollen as affected by irradiation and storage

Summary Apple and pear pollen was irradiated with doses of 0, 50, 100, 250 and 500 krad (gamma rays) and stored at 4°C and 0–10% r.h. From the in-vitro germination percentages an average LD 50 dose of about 220 krad was estimated. For both irradiated and untreated pollen a close and corresponding lineair relationship existed between germination percentage and pollen tube growth.Irradiated pollen was much more sensitive to dry storage conditions than untreated pollen, resulting in less germination and more bursting. Apparently, irradiation caused the pollen cell membrane to lose its flexibility faster than normal. Rehydration of dry-stored, irradiated pollen in water-saturated air restored germination percentages up to their initial levels. The importance of this procedure in germination trials is stressed.     

Water Extraction Process of Chinese Herbal Compound Man Gan Ning

[Objectives]To optimize the water extraction process of Chinese Herbal Compound Man Gan Ning and establish a method for its extraction and content determination...     

Present status and future strategy in breeding faba beans (Vicia Faba L.) for resistance to biotic and abiotic stresses

Progress is being made, mainly by ICARDA but also elsewhere, in breeding for resistance to Botrytis, AScochyta, Uromyces, and Orobanche; and some lines have resistance to more than one pathogen. The strategy is to extend multiple resistance but also to seek new and durable forms of resistance. Internationally coordinated programs are needed to maintain the momentum of this work.Tolerance of abiotic stresses leads to types suited to dry or cold environments rather than broad adaptability, but in this cross-pollinated species, the more hybrid vigor expressed by a cultivar, the more it is likely to tolerate various stresses.     

Optimization of Extraction Technology and Determination of Content of Total Phenols of Leaves in Acanthopanax giraldii Harms

[Objectives] To determine the optimum extraction technology for total phenols of leaves in Acanthopanax giraldii Harms.[Methods]The single factor test and ortho...     

Cytoplasmic male sterility,resistance to gall mite and mildew,and season of leafing out in black currants

Summary Cytoplasmic male sterility (cms) is described in the F₁ hybrids Ribes × carrierei (R. glutinosum albidum × R. nigrum) and R. sanguineum × R. nigrum. In backcrosses to R. nigrum, progenies with R. glutinosum cytoplasm were either all male sterile, or segregated for full male fertility (F) and complete (S) and partial (I) male sterility. Ratios of F:I+S suggested that two linked genes controlled cms, F plants being dominant for one (Rf ₁) and recessive for the other (Rf ₂).Segregation for cms in relation to three linded genes, Ce (resistance to the gall mite, Cecidophyopsis ribes), Sph ₃(resistance to American gooseberry mildew, Sphaerotheca mors-uvae) and Lf ₁(one of two dominant additive genes controlling early season leafing out) indicated that Rf ₁and Rf ₂were in this linkage group. The gene order and approximate crossover values appeared to be: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXafv3ySLgzGmvETj2BSbqef0uAJj3BZ9Mz0bYu% H52CGmvzYLMzaerbd9wDYLwzYbItLDharqqr1ngBPrgifHhDYfgasa% acOqpw0xe9v8qqaqFD0xXdHaVhbbf9v8qqaqFr0xc9pk0xbba9q8Wq% Ffea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qqQ8frFve9Fve9Ff0dme% aabaqaciGacaGaamqadaabaeaafaaakeaacaWGdbGaamyzamaamaaa% baGaaiiiaiaacccacaGGWaGaaiOlaiaacgdacaGG0aGaaiiiaiaacc% caaaGaaiiiaiaacccacaGGGaGaamOuaiaadAgaliaaigdakmaamaaa% baGaaiiiaiaacccacaGGGaGaaiiiaiaaccdacaGGUaGaaiOmaiaacs% dacaGGGaGaaiiiaiaacccacaGGGaGaaiiiaaaacaWGsbGaamOzaSGa% aGOmaOWaaWaaaeaacaGGGaGaaiiiaiaacccacaGGGaGaaiiiaiaacc% cacaGGGaGaaiiiaiaacccaaaGaamitaiaadAgaliaaigdakmaamaaa% baGaaiiiaiaacccacaGGGaGaaiiiaiaacccacaGGGaGaaiiiaiaacc% cacaGGGaGaaiiiaiaacccacaGGGaaaaiaadofacaWGWbGaamiAaSGa% aG4maaaa!6E4D!\[Ce\underline { 0.14 } Rf1\underline { 0.24 } Rf2\underline { } Lf1\underline { } Sph3\]. Crossover values of 0.36 for Ce-Lf ₁, and 0.15 for Lf ₁-Sph ₃were estimated from the relative mean differences in season of leafing out between seedlings dominant and recessive for Ce and Sph ₃.It is suggested that competitive disadvantage of lf ₁-carrying gametes and/or zygotes at low temperatures may be implicated in the almost invariable deficit of plants dominant for the closely linked mildew resistance allele Sph ₃. Poor performance of lf ₁- (and possibly lf ₂-) carrying gametes and young zygotes during periods of low temperature at flowering might also account for the liability of some late season cultivars and selections to premature fruit drop (running off).     

Screening techniques and sources of resistance to parasitic angiosperms

Parasitic angiosperms cause great losses in many important crops under different climatic conditions and soil types. The most widespread and important parasitic angiosperms belong to the genera Orobanche, Striga, and Cuscuta. The most important economical hosts belong to the Poaceae, Asteraceae, Solanaceae, Cucurbitaceae, and Fabaceae. Although some resistant cultivars have been identified in several crops, great gaps exist in our knowledge of the parasites and the genetic basis of the resistance, as well as the availability of in vitro screening techniques. Screening techniques are based on reactions of the host root or foliage. In vitro or greenhouse screening methods based on the reaction of root and/or foliar tissues are usually superior to field screenings and can be used with many species. To utilize them in plant breeding, it is necessary to demonstrate a strong correlation between in vitro and field data. The correlation should be calculated for every environment in which selection is practiced. Using biochemical analysis as a screening technique has had limited success. The reason seems to be the complex host-parasite interactions which lead to germination, rhizotropism, infection, and growth of the parasite. Germination results from chemicals produced by the host. Resistance is only available in a small group of crops. Resistance has been found in cultivated, primitive and wild forms, depending on the specific host-parasite system. An additional problem is the existence of pathotypes in the parasites. Inheritance of host resistance is usually polygenic and its transfer is slow and tedious. Molecular techniques have yet to be used to locate resistance to parasitic angiosperms. While intensifying the search for genes that control resistance to specific parasitic angiosperms, the best strategy to screen for resistance is to improve the already existing in vitro or greenhouse screening techniques.