美国鉴别寄主对中国大豆灰斑病菌反应的研究

以中国大豆灰斑病菌１０个生理小种分别接种于美国的１２个灰斑病鉴别寄主上进行抗性鉴定,参考美国灰斑病菌生理小种对这１２个美国鉴别寄主抗性反应的资料进行比较,结果表明,１２个鉴别寄主对中国灰斑病菌４号生理小种和对美国灰斑病菌１号生理小种的抗感反应一致,其它中国和美国灰斑病菌生理小种没有相似之处。美国鉴别寄主中的Ｂｒａｇｇ和Ｈｏｏｄ两个品种可在中国作抗源利用。建议在建立国际大豆灰斑病统一鉴别体系中,应采用Ｂｌａｃｋ－ｈａｗｋ的感病对照品种。     

玉米弯孢叶斑病菌致病性分化及几种鉴定技术比较

本研究从我国20余个主栽玉米品种和20个骨干自交系中筛选鉴别寄主,并辅助采用RAPD和同工酶电泳的遗传和生理生化分析,对现阶段我国玉米弯孢叶斑病菌致病性分化现状进行了测定。研究表明：自交系沈135、78599-1、 Mo17、477、C8605、E28、7922和黄早4具有较强的鉴别特性,通过8个鉴别寄主将采自我国玉米产区的23株弯孢叶斑病菌分为6个致病类型,其中类型A致病性强、分布广,为优势致病类群;类型D主要分布在我国零星发生的地区,为弱致病类群。不同方法鉴定的结果具有相关性,特别是对那些致病性分化明显、致病性强的菌株三种鉴定方法鉴定结果关系密切,都能对应地划分在同一个组里。     

玉米灰斑病菌致病过程的寄主反应研究

通过对玉米灰斑病菌侵染后的显症过程的系统观察,可在组织水平上说明该病菌与寄主互作反应存在分化或多样性：玉米灰斑病菌不同菌株侵染后显症过程表现出明显的差异;玉米灰斑病菌在侵袭力上存在多样性,菌株间对同一种品种的致病性表现多样化,或者同一菌株对不同品种侵染引起的寄主反应表现为多样性;病斑反应型的分化,玉米灰斑病菌侵染玉米品种或自交系后,主要有7种病斑反应类型,即RH型(长矩形具褪绿晕圈病斑)、RN型(长矩形无褪绿晕圈病斑)、IRH型(不规则形具褪绿晕圈病斑)、IRN型(不规则形无褪绿晕圈病斑)、SH型(斑点形具褪绿晕圈病斑)、RI型(长矩形与不规则形混合病斑)和RS型(长矩形与斑点形混合病斑),若发病严重,病斑连成片,而且这些反应类型出现的频率也不同。     

玉米丝黑穗病菌生理分化研究

利用6个抗病性差异明显的鉴别寄主对玉米丝黑穗病菌进行生理分化鉴定,结果鉴别出7个生理分化致病类型:菌株03-13、03-04、03-07、03-22和03-12属于致病类型Ⅰ;菌株03-23、03-18和03-29属于致病类型Ⅱ;菌株03-20、03-26、03-16和03-14属于致病类型Ⅲ;菌株03-17、03-03、03-11和03-28属于致病类型Ⅳ;菌株03-02和03-08属于致病类型Ⅴ;菌株03-10、03-21和03-25属于致病类型Ⅵ;菌株03-01属于致病类型Ⅶ。高梁丝黑穗病菌对所有的鉴别寄主都不具有侵染力,归属于致病类型Ⅰ。     

东北地区玉米大斑病菌生理分化研究

为明确东北地区玉米大斑病菌的生理分化及小种动态情况,分析玉米大斑病加重的原因。采用常规Ht单基因(Ht1、Ht2、Ht3、HtN)鉴别寄主鉴定技术,对2010年采自辽宁、吉林、黑龙江省22个县(市)88份玉米大斑病菌的菌株进行了生理小种鉴定,共鉴定出0、1、2、N、12、1N、23、2N、3N、12N、123N、123、23N和12N号14个生理小种;东北地区大斑病菌生理分化明显,出现了能够克服多个抗性基因的小种,其中,0号和1号生理小种分别占供试菌株的37.5%和20.5%,为优势小种;所鉴定的88个菌株对Ht1、Ht2、Ht3和HtN抗性基因的毒性频率分别为45.5%,30.7%,15.9%,23.7%。研究结果表明,东北地区玉米大斑病菌生理小种组成及种间的变异频率开始趋于复杂化,不断有新小种出现。玉米大斑病菌新小种出现0号和1号以外其他小种,出现频率升高和品种抗性丧失是导致玉米大斑病发生的重要原因。     

福建省玉米小斑病菌的致病型及其群体结构分析

为了解福建省玉米小斑病菌的致病型及其群体结构,采用病斑长度测量法研究了2014—2015年采自福建省7个地区的247个菌株侵染不同细胞质玉米品种‘C103T’、‘C103C’、‘C103S’和‘C103’后叶片的病斑型。结果表明,所有供试菌株均可引起4个玉米品种发病,其病斑长度平均值介于1.15~5.40 mm、1.06~4.70 mm、1.09~4.84 mm和1.15~5.21 mm之间。根据病斑长度将病斑分为Ⅰ和Ⅱ型,其菌株出现频率分别为80.26%和19.74%。依据各菌株依次在4个不同品种玉米上的病斑型,供试菌株群体被划分出15个致病型,其中致病型CHP15(病斑反应型Ⅰ-Ⅰ-Ⅰ-Ⅰ)为优势型,致病型CHP11(病斑反应型Ⅲ-Ⅰ-Ⅰ)为亚优势型,优势型和亚优势型分别占供试总菌株数的57.49%和9.72%。不同地区菌株之间的致病型组成及其出现频率存在多样性。此外,其中的235个O小种菌株也出现了14个致病型,菌株间的致病力存在明显的分化。     

黑龙江省北部七县市玉米大斑病菌小种鉴定

玉米大斑病的发生流行常对玉米生产造成严重损失,而该病的发生与病原菌生理小种变异密切相关,新生理小种的出现往往导致生产上玉米品种抗性丧失。为此,在玉米主产地及时准确地调查该地区大斑病菌的小种变异,对指导抗病育种和抗病品种的生产推广有重要意义。本研究从黑龙江省第三、第四积温带玉米产区的7个县市中采集病害标样,通过组织分离获得了21个玉米大斑病菌菌株。经采用玉米大斑病菌生理小种鉴别寄主接种鉴定,发现在上述区域内仅有13N和23N 2个生理小种,小种构成较为简单,并且以13N号小种为主。     

新疆棉花黄萎病新型菌株NH1致病性鉴定及抗病分析

为抗病育种提供新的强致病力资源菌株,分析新疆主要产棉区棉花黄萎病病原菌的形态特征、菌系变异和致病力分化情况,探究菌株的抗病水平。本研究从新疆南、北疆植棉区共采集35株棉花黄萎病病杆,经分离纯化、形态鉴定及菌落观察,筛选出1株致病力较强的菌株NH1作为供试菌株。采用鉴别寄主法,检测发现NH1菌株对20个不同抗性的寄主品种均有表现不同程度的致病力。抗性鉴定结果显示,参与鉴别寄主的20个品种材料中未出现免疫或高抗的材料,表现抗病的材料有5个,占鉴定材料的25%;感病品种11个,占鉴定材料的55%;耐病的材料4个,占鉴定材料的20%。根据病情指数进行划分,NH1菌株的相对病情指数为37.1,大于30.1,生理型鉴定为1号生理小种,PCR鉴定为落叶型。结果表明,NH1菌株为生理型1型的强致病力落叶型菌株,可作为新的强致病力菌,对提升棉花黄萎病的统防统治具有重要实践意义。     

福建省玉米小斑病菌侵染不同细胞质玉米品种的病斑型及其致病型群体结构分析

[目的]为了解福建省玉米小斑病菌的致病性及其群体结构,[方法]研究了2014-2015年采自福建省7个地区的247个菌株侵染不同细胞质玉米品种C103T、C103C、C103S和C103后叶片的病斑型,[结果]结果表明,所有供试菌株均可引起4个玉米品种发病,其病斑长度平均值分别介于1.15 mm-5.40 mm、1.06 mm-4.70 mm、1.09 mm-4.84 mm和1.15 mm-5.21 mm之间。根据病斑长度将病斑分为I和II型,其菌株出现频率分别为80.26%和19.74%。依据各菌株依次在4个不同品种玉米上的病斑型,供试菌株群体被划分出15个致病型,其中致病型CHP15(病斑反应型I-I-I-I)为优势型,致病型CHP11(病斑反应型II-I-I-I)为亚优势型,优势型和亚优势型分别占供试总菌株数的57.49%和9.72%。[结论]不同地区菌株之间的致病型组成及其出现频率存在多样性。此外,其中的235个O小种菌株也出现了14个致病型,菌株间的致病力存在明显的分化。     

河北省玉米小斑病菌生理小种鉴定及群体动态变化

1987-2003年从河北省10个地区采集玉米小斑病标样,对分离出的288个玉米小斑病菌菌株进行了生理小种鉴定。在鉴定的年度范围内,玉米小斑病菌T小种、C小种、S生理型与O小种的分离频率在地区间和年度间存在显著差异,O小种的平均分离频率明显高于其他小种,是河北省玉米小斑病菌的优势小种。在年度间,C小种的分离频率也存在显著差异,T小种、S生理型、O小种的分离频率无显著差异。O小种具有不同致病力,强致病力菌株和中等致病力菌株的出现频率较弱致病力菌株高,强致病力菌株主要分布在河北省的东部和南部,弱致病力菌株主要分布在河北省北部。     

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.     

A note on the origin of Kalanchoë x vadensis Boom & Zeilinga (Crassulaceae)

Summary K x vadensis is a hybrid of K. blossfeldiana and K. marmorata obtained after doubling the number of chromosomes.     

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...     

Avoidance of leaf rust fungi in wild relatives of cultivated cereals

Summary Avoidance of rust fungi that was based on poor appressorium induction was previously found in Hordeum chilense. In the present study 95 accessions of Triticeae were screened for avoidance of Puccinia hordei. The percentage of appressorium formation per germinated spore ranged from 6 to 90%. On none of the 41 accessions of Aegilops, Agropyron, Elymus, Secale, Thinopyrum or Triticum studied was the rate of appressorium formation lower than 25%. Lower rates of appressorium formation were, however, found on accessions of wild barley species Hordeum brachyantherum, H. marinum, H. parodii and H. secalinum. Its implications in cereal breeding are discussed.     

Variation in forage grasses as hosts of the root-knot nematode Meloidogyne naasi (Franklin) and selection for resistance in ryegrass

Summary Reactions of 13 grasses to Meloidogyne naasi varied with species; ryegrasses, fescues and their hybrids were generally susceptible and cocksfoot and timothy resistant. Marked variation in host resistance levels occurred between genotypes within cultivars.Selection of single plants, followed by tests on replicate tillers, identified resistant and susceptible genotypes in both Italian and perennial ryegrass cultivars. Resistant plants had few nematode-induced galls and fewer females and eggs than susceptibles. There was more or less continuous variation, with many genotypes intermediate between extremes of resistance and susceptibility. Selected resistant and susceptible genotypes are of use in assessing variation in nematode populations and as controls for breeding and selection programmes.     

Current and future strategies in breeding lentil for resistance to biotic and abiotic stresses

Lentil production is limited by lack of moisture and unfavorable temperatures throughout its distribution. Waterlogging and salinity are only locally important. Progress has been made in breeding for tolerance to drought through selection for an appropriate phenology and increased water use efficiency and in breeding for winter hardiness through selection for cold tolerance.The diseases rust, vascular wilt, and Ascochyta blight, caused by Uromyces viciae-fabae, Fusarium oxysporum f. sp. lentis, and Ascochyta fabae f. sp. lentis, respectively, are the key fungal pathogens of lentil. Cultivars with resistance to rust and Ascochyta blight have been released in several countries and resistant sources to vascular wilt are being exploited. Sources of resistance to several other fungal and viral diseases of regional importance are known. In contrast, although the pea leaf weevil (Sitona spp.) and the parasitic weed broomrape (Orobanche spp.), and to a lesser extent the cyst nematode (Heterodera ciceri), are significant yield reducers of lentil, no sources of resistance to these biotic stresses have been found. Directions for future research in lentil on both biotic and abiotic stresses are discussed.     

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.     

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...