辣椒抗黄瓜花叶病毒(CMV)基因的ISSR标记

辣椒(Copicum annuum L.)抗黄瓜花叶病毒(CMV)一直是辣椒育种的主攻目标之一.本研究以辣椒抗CMV品种VC16a和感CMV品种SS69杂交的F2群体60个单株材料,通过人工接种鉴定,采用高抗单株和高感单株分别构建抗、感基因池,利用BSA法筛选了40条ISSR引物,其中引物I-34在抗感病池中扩增出450 bp多态性片段,通过F2单株验证后证明I-34450与抗CMV基因紧密连锁,其遗传距离为27.3 cM,为辣椒抗CMV分子标记辅助育种奠定了基础.     

辣椒抗黄瓜花叶病毒病候选基因功能鉴定

黄瓜花叶病毒(CMV)为辣椒的主要病害,鉴定辣椒抗CMV基因并研究其抗性机理是辣椒抗CMV育种的理论基础。前期研究发现,CA02g19570和CA02g19600为辣椒抗CMV主效QTL (qCmr2.1)的候选基因,其中CA02g19570可能性更高。本研究以辣椒抗CMV材料PBC688和易感CMV材料G29为试验材料,采用qRT-PCR和VIGS技术验证候选基因CA02g19570和CA02g19600在辣椒抗CMV中的功能。结果表明,接种CMV后0～28 d的发病过程中,抗病材料PBC688和感病材料G29中的CA02g19570基因表达量均显著上调,且抗病材料中基因上调水平显著高于感病材料;而CA02g19600在抗、感材料中的基因表达模式无显著规律。在PBC688中沉默CA02g19570后,有6个(60%)植株在接种CMV后出现严重的系统花叶症状,CA02g19570的相对表达量显著下调;而沉默CA02g19600后,仅有2个(20%)植株出现轻微的花叶症状。本研究认为CA02g19570是辣椒2号染色体上的抗CMV主效QTL (qCmr2.1)的抗性基因。     

与黄瓜白粉病抗病基因紧密连锁的SSR分子标记

黄瓜白粉病是影响黄瓜生产的主要病害,为建立黄瓜抗白粉病分子标记辅助选择体系,我们以黄瓜抗白粉病亲本WIS2757和感白粉病亲本19032以及它们的F2群体为试材,采用SSR分析技术,对相关抗性基因的连锁分子标记进行了研究。获得了2个与黄瓜白粉病主效抗病基因连锁的SSR分子标记SSR97-200,SSR273-300,连锁距离分别为5,13cM,这些SSR标记可以作为黄瓜抗白粉病辅助选择的分子标记。     

棉花黄萎病抗性分子标记辅助选择改良研究进展

由大丽轮枝菌引起的棉花黄萎病已成为当前我国棉花可持续生产的主要障碍之一。分子标记辅助选择打破传统表型选择的局限性,实现对基因型的直接选择,有助于提高选择效率。然而分子标记辅助选择在棉花抗黄萎病育种中的应用不充分。概述棉花黄萎病抗性分子标记辅助选择改良的研究进展,讨论改良过程中遇到的问题,在总结相关研究的基础上讨论分子标记辅助选择在棉花抗黄萎病育种中的应用前景,以期为我国棉花抗黄萎病分子育种提供有用信息。     

花生黄曲霉侵染抗性的AFLP标记

本研究利用抗、感黄曲霉菌侵染的花生品种为亲本配制杂交组合“J11×中花5号”,以其F₂分离群体为研究材料，采用AFLP技术和BSA分析方法，获得了与花生黄曲霉菌侵染抗性连锁的2个分子标记，标记与抗性间的遗传距离分别为8.8 cM和6.6 cM;利用获得的分子标记对抗、感黄曲霉的花生种质资源进行了分子鉴定，实验结果表明分子标记与抗性鉴定结果具有较高的一致性，证实了两标记应用于研究群体之外的育种潜力。该抗侵染分子标记的建立为开展花生抗黄曲霉辅助选择育种提供了有效的筛选技术。     

烟草CMV抗性鉴定及抗性基因的SSR标记研究

本研究以抗黄瓜花叶病毒病的烟草品种铁把子和台烟8号,感病品种NC82和中烟15为亲本,构建F1、F2、BC1代分离群体,并对它们进行CMV的接种鉴定和抗性遗传分析,结果表明铁把子和台烟8号对CMV的抗性是由1对隐性基因控制的.依据混合群体分组分析法(BSA),从F2代群体植株中选取DNA建立黄瓜花叶病毒病的抗病基因池和感病基因池,利用135对SSR引物进行分子标记和分析,得到标记SM1350与来源于铁把子的CMV抗性基因间的遗传距离为8.64 cM,标记SM2270与来源于台烟8号的CMV抗性基因间的遗传距离为3.92 cM.     

辣椒抗马铃薯Y病毒(PVY)研究进展

马铃薯Y病毒(Potato virus Y,PVY)是限制辣椒生产的主要病毒病害之一,该病毒是马铃薯Y病毒组(Potyvirus)的典型代表,能够侵染辣椒等茄科作物,造成重大的经济损失。应用抗病资源、选育抗病品种是克服PVY对辣椒危害最为经济有效的方法。文中综述了辣椒PVY病毒的发现、流行和检测与分类,并针对辣椒抗PVY育种工作描述了抗性鉴定方法、抗原筛选、抗性遗传、分子定位和标记开发的研究进展,介绍了PVY抗性基因与病毒的互作机理,并就辣椒抗PVY育种中存在的问题及未来研究方向进行了讨论。     

分子标记技术在辣椒研究中的应用进展

分子标记是生物学研究的一个重要工具,在作物新品种选育等方面发挥着越来越重要的作用。为了构建辣椒分子标记辅助育种技术体系,以实现常规育种技术与现代生物技术的有机结合,归纳了分子标记技术在辣椒种质遗传多样性、分子连锁图谱构建、分子标记辅助选择育种和基因定位等方面的已有研究成果;认为分子标记技术在辣椒上的应用研究系统性还不强、基础分子信息比较缺乏、遗传图谱还不精细,建议在实用新型分子标记开发、核心种质分子信息库建立、优良作图群体及精细遗传图谱构建等方面加强系统深入的研究。     

稻瘟病抗性基因特异性分子标记的开发及应用进展

由稻瘟病菌引起的水稻稻瘟病是影响水稻生产的重要病害之一,培育和合理利用抗性品种是控制稻瘟病最经济有效、环保的措施。虽然DNA分子标记分子已经被广泛用于基于分子标记辅助选择技术(MAS)的水稻抗性育种工作中,但是分子标记辅助选择育种的效率取决于分子标记与目标基因的连锁距离。目前,已经克隆的稻瘟病抗性基因多达26个,其全基因组序列已经公开发表,这将有利于基因特异性分子标记的开发。基因特异性分子标记与基因共分离,在分子育种过程中实现了对目标基因的直接选择,有可能成为未来分子育种技术中鉴定目标基因的主流工具。本研究综述了稻瘟病抗性基因特异性分子标记的开发及应用情况,并对已经开发成功的基因特异性分子标记相关信息进行整合,旨在为育种家在分子标记的选择上提供指导信息。     

水稻抗稻瘟病基因Pi-k~h的分子检测

水稻稻瘟病抗性基因Pi-kh对不同地区的稻瘟病菌表现出较广谱的抗性,被广泛应用于水稻抗稻瘟病育种。为明确稻瘟病抗病基因Pi-kh在水稻新品系中的基因型及分布情况,以期为水稻新品种选育提供抗性亲本,利用稻瘟病抗病基因Pi-kh的功能标记对184份水稻新品系进行分子标记检测分析。结果表明,在184份材料中,含抗病基因Pi-kh的材料106份,其中86份为基因型纯合体,20份为基因型杂合体,二者所占比例为65.76%。这些材料为培育抗稻瘟病优良水稻品种提供了抗病基因。研究结果可为水稻抗稻瘟病的分子标记辅助育种提供帮助。     

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.     

Mechanisms and diversity of resistance to sorghum shoot fly,Atherigona soccata

Sorghum shoot fly, Atherigona soccata, is one of the important pests of postrainy season sorghums. Of the 90 sorghum genotypes evaluated for resistance to this pest, RHRB 12, ICSV 713, 25026, 93046 and 25027, IS 33844‐5, Giddi Maldandi and RVRT 3 exhibited resistance in postrainy season, while ICSB 463, Phule Anuradha, RHRB 19, Parbhani Moti, ICSV 705, PS 35805, IS 5480, 5622, 17726, 18368 and 34722, RVRT 1, ICSR 93031 and Dagidi Solapur showed resistance in rainy season, suggesting season‐specific expression of resistance to A. soccata. ICSB 461, ICSB 463, Phule Yasodha, M 35‐1, ICSV 700, 711, 25010, 25019 and 93089, IS 18662, Phule Vasudha, IS 18551 and 33844‐5 and Barsizoot had fewer deadhearts than plants with eggs across seasons, suggesting antibiosis as one of the resistance mechanism. Five genotypes exhibited resistance with high grain yield across seasons. Correlation, path and stepwise regression analyses indicated that leaf glossiness, seedling vigour, trichome density, oviposition and leaf sheath pigmentation were associated with the expression of resistance/susceptibility to shoot fly, and these can be used as marker traits to select and develop shoot fly‐resistant sorghums.     

Breeding forage grasses for organic conditions

Herbage yield trials are necessary to test if candidate varieties are well suited for organic conditions. In order to elucidate a particular suitability for organic conditions, we run such trials in parallel under both organic and conventional conditions. Here, we report on second and third year results of the sowings 2004 and 2005. These trials are part of a targeted breeding programme for organic conditions. Irregular colonisation of pure grass plots with adventitious plants, in particular white clover, was recognized as a major constraint to the quality of the results obtained under organic conditions. The coefficients of variance in dry matter yield almost doubled when compared to conventional trials, and significant differences in annual yield among varieties were rare. However, when herbage yield was corrected for the estimated fraction of adventitious plant colonization at each cut, the number of instances with statistically significant differences for annual yield among varieties increased more than fourfold. Dry matter yields under organic and conventional conditions were significantly and positively correlated. However, analysis of variance showed a significant culture type by variety interaction for annual dry matter yield in 12 out of 24 trials. When diploid and tetraploid varieties of the same Lolium species were tested in one common trial, only tetraploid varieties were identified as being particularly well suited for organic conditions, while in these trials, the great majority of apparently poorly suited varieties were diploid. This suggests that breeding tetraploid Lolium varieties is promising when aiming at a favourable response to organic agriculture.