Progeny testing for resistance to potato virus Y: a comparison of susceptible potato cultivars for use in testcrosses with resistant parents

Summary For potato breeding or genetical research purposes, the number of copies of a dominant major gene for resistance to potato virus Y in a parent clone can be determined by test-crossing with a susceptible parent and observing the segregation ratio of resistant to susceptible seedlings in the progeny. In a comparison of different susceptible cultivars for use in test-crosses for this purpose, their progenies differed in the clarity of symptoms and parental phenotype proved an unreliable guide. Cvs Maris Piper, Arran Peak and Dr MacIntosh were found to be suitable tester parents, Pentland Squire less so and cv. Désirée was confirmed as having a major gene conferring incomplete resistance. It was found advisable to test-cross with more than one susceptible parent.     

大豆对大豆花叶病毒SC18株系的抗性遗传和基因定位

大豆花叶病毒(soybean mosaic virus,SMV)病是我国大豆生产上的一种主要病毒病害,SMV株系SC18是我国东北和南方两大产区的优势株系,在黄淮大豆产区亦零星发生。本研究对5个抗×感杂交组合衍生后代分离群体接种SC18后,发现各组合F_1均抗病,F_2表现3∶1(抗∶感)分离比,F_(2∶3)表现1∶2∶1(抗∶分离∶感)的分离比,表明5个抗病亲本(中作00-683、滨豆95-20、东大2号、中品661和RN-9)对SC18的抗性由一对显性基因控制。抗×抗杂交组合"中作00-683×东大2号"衍生后代分离群体接种SC18,F_2出现15∶1(抗∶感)的分离比,表明中作00-683与东大2号可能各携带一对显性基因,控制对SC18的抗性,且独立遗传;抗×抗杂交组合"中作00-683×滨豆95-20"的F_1、F_2和F_(2∶3)在接种SC18后均未检测出感病株,表明中作00-683与滨豆95-20所携带的对SC18的抗性基因是等位的。利用RN-9×7605重组自交家系将RN-9对SC18的抗病基因Rsc18定位到大豆6号染色体(C2连锁群)SSR标记Satt286和Satt277之间,遗传距离为6.12和4.69 cM。     

花生种子抗黄曲霉侵染性状遗传控制的研究

以高抗黄霉侵染亲本湛秋48和高感亲本粤油92及杂种后代F1，BC1，F2，F3为分析材料，研究了花生抗黄曲霉侵染的遗传控制，结果表明花生对黄曲霉侵染的抗性没有细胞质效应和胚乳效应，是由母株（2n）基因控制，表现为一对主基因和微效基因混合遗传模式。     

Inheritance of resistance to sclerotinia stem rot (Sclerotinia trifoliorum) in faba beans (Vicia faba L.)

Stem rot, a fungal disease caused by Sclerotinia trifoliorum Eriks., is often a serious problem in many important forage legumes including faba beans (Vicia faba L.). Understanding the inheritance of resistance to the disease is essential for effective breeding of resistant cultivars. Experiments were conducted to study the inheritance of resistance to stem rot of faba beans. The F₁, F₂, and the backcross generations of five crosses between four resistant and four susceptible populations (Alto × Polycarpe, A-90 × Polycarpe, ILB-1814 × A-247, A-90 × A-244, VT × Tanagra) were used. The eight populations were crossed properly in the field, and progenies of F₁ and F₂, as well as backcross progenies of F₁ with each of their parents, were evaluated for resistance to stem rot disease under controlled conditions after artificial inoculation of the plants with carrot root pieces colonized by the fungus. On the assumption that inheritance of stem rot resistance is governed by a single dominant gene, no significant differences were found between the observed and the expected frequencies of resistance for progenies, except for one cross. As the expression of resistance to the disease fits the expected ratios for a single dominant gene model, it is concluded that the inheritance of resistance to sclerotinia stem rot in the evaluated faba bean populations is controlled by a single dominant gene.     

Correlation between resistance to late blight in foliage and tubers in potato clones from parents of contrasting resistance

Summary The relationship between resistance to late blight in foliage and tuber was examined on 50 clones of each of five progenies from crosses where one parent was resistant in both foliage and tuber and the other susceptible. Foliage resistance was assessed in a field trial and tuber resistance in a laboratory test on glasshouse-grown tubers. The genetical and environmental components of variance and the phenotypic and genetical correlations between foliage and tuber blight scores were determined for each progeny. Foliage and tuber resistance were correlated, indicating either that both are determined by the same genes or by different linked genes. The environmental component of variation was greater for tuber blight than foliage blight. We suggest that the most effective way of selecting for resistance to both aspects of the disease in a breeding programme is to select those resistant in the foliage and then screen them for tuber resistance.     

Inheritance of extreme resistance to potato virus Y in potato

Summary Segregation for extreme resistance to PVY was evaluated in progenies derived from crossing two extremely resistant potato clones with parents differing in resistance. Resistance was evaluated after mechanical inoculation with PVY^O and PVY^N, and after graft inoculation with PVY^O. Biological and serological tests (ELISA) were used for virus detection. The extreme resistance is governed by a single dominant gene, but observed segregations deviated from the expected ratios. Considerable modifying effects were detectable, depending on the potato genotype and virus isolate, for a significant excess of susceptible genotypes was observed in some progenies. Moreover, genotypes with non-parental types of resistance to PVY were observed.     

ALHAMRA,STEMSTER, SKIRZA: Three new cultivars from Caithness,Scotland

A new private potato breeding company was established in Caithness, Scotland in 1983. In August 1986 the first three potato varieties from ‘Caithness Potato Breeders Ltd.’ were accepted onto the United Kingdom National List of Potato Varieties. These three cultivars—ALHAMRA (maincrop), STEMSTER (maincrop), SKIRZA (second early), are all red-skinned and result from a cross between ‘Desiree’ and ‘Maris Piper’. All three cultivars have demonstrated high yield potential, ‘Stemster’ particularly so, and all are resistant to one pathotype of the golden (potato cyst) nematode, unlike ‘Desiree’ their red-skinned parent.     

小麦品种Gaby的抗条锈基因遗传分析

小麦品种Gaby是重要的每锈病抗源品种，为了明确其抗锈遗传规律。用条中29号、条中32号书水源类型菌系水11分别接种该品种的双列杂交F2、F3代各株系幼苗，对该品种进行了抗条锈性遗传分析。结果表明，Gaby有3对基因抗中国小麦条锈菌小种。对条中29，其正反交均表现1对显性抗病基因起抗病作用；对水11菌系，Gaby做母本时，有3对显性基因起抗病作用（其中2对表现为累加作用），做父本时其抗性由1对完全显性抗病基因和1对隐性基因控制；对条中32，Gaby做母本时有2对基因起抗病作用（可能是2对隐性基因，也可能是存在累加作用的2对显性基因），做父本时可能存在1对显性基因和2对隐性抗病基因控制抗病性。     

杂交小麦杂种一代白粉病抗性表现规律的研究

为探讨杂交小麦杂种一代白粉病的抗性表现规律,以陕西不同地区小麦白粉病流行菌种做菌源,通过田间和苗期接种,对9份抗、感白粉病小麦亲本材料和9份大田感病品种及其杂交F1代进行抗病性鉴定,并结合SCAR和SSR分子标记进行了检测.结果表明:(1)以N95175、N9209为亲本的杂交F1含有Pm21基因,苗期和成株期抗病性均很好,与抗病亲本的抗病性表现基本一致,符合显性遗传,其抗病性主要由显性单基因控制.(2)以N9134、N9227A为亲本的杂交F1含有PmAS846基因,成株期抗病性较好,苗期大部分表现抗病;以N9227A为亲本的杂交F1中有40%的杂交组合表现中感,该抗性基因不完全符合单基因显性遗传,其表达在一定程度上受遗传背景及环境的影响.(3)中国春为苗期感病、成株期抗病材料,其与抗病亲本杂交F1代的抗病性接近或略高于抗病亲本;与感病品种杂交F1代的抗病性介于双亲之间.(4)白粉病遗传属于细胞核遗传,正反交F1代苗期抗病性无明显差异,杂交种的抗病性与双亲相关.因此, 在组配小麦强优势杂种组合时应尽量选用抗病的品种作为亲本之一,并考虑慢病性品种的应用.     

携有抗白叶枯病新基因Xa23水稻近等基因系的构建及应用

 1993～1998年,构建了携有抗稻白叶枯病新基因Xa23的近等基因系,命名为CBB23。以全生育期高度感病并具有改良株型的籼稻品种JG30为轮回亲本，与携有Xa23的抗性供体H-4杂交，JG30/H-4的F1通过回交、自交直至B5F4，各世代均用与目标基因Xa23相对应的专化小种菌系P6人工接种鉴定，同步进行株型和农艺性状选择，直至抗性稳定和农艺性状类似其轮回亲本。比较了CBB23 (携Xa23) 和IRBB21 (携Xa21) 对20个菌系包括10个菲律宾小种、3个日本小种和7个中国病原型代表菌系的抗谱，Xa23抗所有20 个菌系； Xa21 抗19个菌系，对菲律宾10号小种则高度感病。用近等基因系CBB23构建了JG30/CBB23组合的F2分离群体，通过SSR标记筛选，初步将Xa23定位于水稻第11染色体。进一步筛选出3个与Xa23更紧密连锁的AFLP标记。其中的APKj23与Xa23之间的图距约为1.0 cM。并报道了在抗病育种中已有效的应用了携有Xa23的近等基因系 CBB23。     

大豆对SMV1株系抗性基因的分子标记研究

大豆花叶病毒病是世界大豆产区危害较重的主要病害,本实验高抗SMV1株系黑农39为母本,高感SMV1株系品种合丰25为父本配置杂交组合,对F1、F2代接种SMV1进行田间抗性鉴定和抗病性遗传学分析,通过接种鉴定亲本F1、F2并代的抗性表现,证明,对SMV1号株系的抗性是由一对显性基因决定的.利用RAPD技术在抗感池间寻找多态性标记,通过筛选引物,获得重复性最好的随机引物OPN11.并采用BSA法在黑农39和抗病池扩增出OPN1400片段,在合丰25和感病池扩增出OPN1300片段,在F1同时扩增出OPN11400和OPN1300.用该引物分析黑农39×合丰25的F2扩增个体,共显性的RAPD标记OPN1400/1300与黑农39抗病基因的遗传距离为8.2cM.     

Heterosis and combining ability analysis for resistance to early blight (Alternaria solani) in potato

Summary In an epiphytotic year of early blight, data were recorded on its incidence in 72 progenies (18 females x 4 males) and their parents planted in a randomised complete block design at the Punjab Agricultural University, Ludhiana, India. Combining ability analysis showed that both additive and non-additive gene action were important, with a preponderance of the latter in the inheritance of resistance to early blight. In general, progenies were as good as or better than mid-parent values. Crosses involving both or at least one parent with good general combining ability resulted in heterotic early blight resistant progenies. Promising parents and crosses were identified.     

Resistance to potato virus Y inSolanum tuberosum spp.andigena

Tests were made on lines ofSolanum tuberosum spp.andigena to determine 1) whether resistance to potato virus Y exists in the Andigena germplasm, 2) the nature of its inheritance, and 3) the type of resistance. Results of the isolation and identification studies indicated that the pathogen involved was a common strain of potato virus Y. Under field conditions susceptible plants frequently escaped infection. However, field exposures over two seasons resulted in the same ratios as tests in which the same progenies were mechanically inoculated. Mechanical inoculation at the seedling stage proved to be a reliable means of transmission and resulted in accurate screening for resistance. Of 641 tub × tub clones tested, all were susceptible to the virus. Of 366 tub × adg clones tested, 170 were resistant and 196 were susceptible. This fits a 13:15 ratio, assuming random chromatid segregation and a single dominant gene conferring resistance. Plants that were resistant following mechanical transmission were also resistant when inoculated by aphids, indicating the reliability of mechanical transmission as a means of screening for resistance. To determine the type of resistance, top-graft and approach-graft tests were made. Failure to recover the virus from resistant plants inoculated by either grafting method suggests that immunity is the type of resistance involved.     

Ergebnisse einer Diallelanalyse zur Vererbung der Resistenz gegenSynchytrium endobioticum (Schilb.) Perc., Pathotyp 1 (Dl) bei Kartoffeln (Solanum tuberosum L.)

Zusammenfassung Die Nachkommenschaften eines Diallels mit 10 Eltern, ohne reziproke Kreuzungen, wurden gegen Pathotyp 1 (Dl) des Kartoffelkrebses geprüft. Aufgrund der Aufspaltung in resistent und anf?llig lassen sich 5 genotypische Gruppen unterscheiden. Zwei Gruppen entsprechen in ihrer Resistenzvererbung dem einfaktoriellen Modell bei Autotetraploiden auf duplexer bzw. simplexer Basis. Der Nachweis von zwei weiteren Genotypen, die sich nicht einordnen lassen, l?\t eine h?here genetische Varianz erkennen, als nach dem autotetraploiden Modell theoretisht zu erwarten ist. Die M?glichkeit der Identifizierung weiterer Genotypen wird nicht ausgeschlossen.

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Summary The progeny of a diallel cross between 10 clones of table potatoes were tested for resistance toSynchytrium endobioticum Pathotype 1. Of the 10 parent clones, 9 were resistant, based on the characteristic defence necrosis, and one was very susceptible. In total 45 hybrid and 10 selfed progenies were tested with 60–100 genotypes in each case. The mean performance of each clone was assessed using the percentages of resistant genotypes for all 9 combinations with other clones, and the selfs. The 10 clones are arranged in Table 1 according to their rankings for this parameter. Five groups of genotypes (I–V) can be recognized; these are significantly different from one another. The mean values of the selfs for individual groups, and the combinations with the susceptible parent are also given. From these results it can be concluded that the clones in Groups I–III inherited resistance as if controlled by a single major dominant gene in the simplex or duplex condition in the autotetraploid. The susceptible parent gave a nulliplex-type. The corresponding test results given in Table 2 confirm these conclusions. According to Table 1, clones (4) and (9) do not fit into Groups I and III. They have another genotype. Since the parents used here cover only a small range of possible genotypes, no generally valid statements can be made about the number of groups and the frequency of the genotypes in the groups for all cultivars and clones ofSolanum tuberosum. Inheritance studies of wart resistance by other authors confirm the assumption that further genotype groups may be identified. Greater genetic variation can be expected than is theoretically possible in the single factor model of autotetraploidy.

     

Heritability of resistance in maize to sorghum downy mildew (Peronosclerospora sorghi (Weston and Uppal) C.G. Shaw)

Host-plant resistance is an effective and economical means of controlling downy mildew (DM) diseases in maize (Zea mays L.). Crosses involving 10 inbred maize lines in all possible combinations (diallel cross) showed that susceptibility to sorghum DM (Peronosclerospora sorghi (Weston and Uppal) C. G. Shaw) is generally inherited as a dominant characteristic. However, progenies of crosses between one of the lines (CM105) resistant to DM, and susceptible lines, showed intermediate levels of resistance, indicating that several genes are involved and that their effects are additive. Progenies of crosses between resistant lines were more resistant than their parents, probably because of interactions between different resistance genes (epistasis). Both additive and non-additive gene action was detected by partitioning gene effects by generation mean in each 16 DM-resistant × DM-susceptible combinations, which indicates that the reactions of maize to DM are governed by several genes (i.e. polygenically) and that the inheritance of resistance is complex. An inbred line from Mexico, Tuxpeno Gpo. 48-Var. 168-1, is a particularly promising general source of resistance to DM.     

Combining Ability for Foliar Resistance to Late Blight [<Emphasis Type="Italic">Phytophthora infestans</Emphasis> (Mont.) de Bary] of Potato Cultivars with Different Levels of Resistance

Combining ability for resistance of potato to late blight (LB) was analyzed by testing segregating seedling progenies obtained from a full diallel crossing design between 3 potato parent cultivars with different levels of LB resistance and a North Carolina Mating Design II with the same resistant parents as females crossed to 2 LB susceptible male parents, against a complex race of P. infestans. Artificial inoculation was conducted under greenhouse conditions in Dalat, Vietnam at 1500 m above sea level. Percentage of foliage infection was recorded visually at 5 days intervals until 25th day after inoculation when the susceptible check was totally destroyed. General combining ability effect was significant and predominant, indicating that in the inheritance of resistance to LB, additive gene actions are more important. Specific combining ability was significant only for crosses between resistant parents, but insignificant for those between resistant and susceptible parents. In almost all cases, no significant reciprocal effect was found. Cultivar C88 was the best general combiner for resistance to LB. There were evidences that 1) the major genes R1, R3a and Rpi-blb1 alone are not enough to condition a good level of resistance to the isolate used; 2) the resistance of C88 was plausibly mostly due to presence of the gene R2, which is probably the main genetic factor of the durable resistance of this cultivar and, 3) the resistance to LB in potato seems background dependent, the background being the set of nuclear factors (major or minor genes) whose expression collectively affects the resistance level.     

利用功能标记鉴定普通野生稻中的白叶枯病抗性基因

 以9个菲律宾白叶枯病菌小种对供试的9份普通野生稻（Oryza rufipogon Griff.）及1份高感白叶枯病材料IR24进行抗性鉴定,发现IR24对所有的菌株都表现为高感, 6份野生稻材料对9个菌株表现全抗,占参试野生稻总数的67%。取自广西玉林的1份材料只感PXO280(P8),海南万宁的1份材料感PXO71(P4),广州高州的1份材料对PXO79、PXO99和PXO339感病,而这几份材料对其余菌株都表现为抗病,说明每份材料至少含有1个抗性基因。利用已克隆的白叶枯病抗性基因xa5、xa13、Xa21和Xa27的功能标记检测,结果表明9份供试普通野生稻中都不含抗性基因xa5、Xa21;5份为显性Xa13纯合体,4份为隐性抗病xa13杂合体;5份为抗病显性Xa27纯合体,3份为隐性xa27纯合体,1份材料中xa27和Xa27都不存在。     

野生二粒小麦抗条锈病基因 YrH52的RGA分子标记

为开发与野生二粒小麦抗条锈病基因YrH52紧密连锁的分子标记,并为该基因的克隆及应用奠定基础,运用RGA (Resistance gene analog) 分子标记法,以 YrH52定位作图F₂群体形成的F₄抗性和感病基因池（Gene pool）及其亲本（抗病材料H52与感病材料Ldn）进行多态性筛选分析,共获得17个RGA分子标记。使用已有的遗传图并进行MultiPoint分析,构建了由与抗性（H）和感病(L) 两个亲本对应的显性位点组成的两个遗传图,即H遗传图和L遗传图。在H图中, YrH52与10个RGA标记,即 X_uhw3, X_uhw17, X_uhw18, X_uhw23, X_uhw36, X_uhw38, X_uhw46, X_uhw59, X_uhw62 和 X_uhw73 紧密连锁, 其中 X_uhw23 标记为共显性分子标记,连锁距离为1.0 cM。在L图中,发现 X_uhw57, X_uhw68, X_uhw189, X_uhw192及其 X_uhw23与 YrH52 相聚成簇（Cluster）。本研究结果说明RGA分子标记结合集群分离分析法 （Bulked segregant analysis,BSA）是一种快速开发与小麦抗病基因紧密连锁标记的有效方法,对小麦抗条锈病分子育种和抗病基因的克隆具有促进作用。     

Bacterial wilt resistance in the progenies of the fusion hybrids between haploid of potato andSolanum commersonii

Bacterial wilt of potatoes, which used to be a widespread disease in tropics and subtropics, has become a threat to potato production in temperate region. The diploid species Solanum commersonii has several desirable characteristics including cold tolerance and resistance to several diseases. Selected somatic hybrids between S. tuberosum dihaploid and bacterial-wilt-resistant S. commersonii clones were cross pollinated with S. tuberosum cultivars for further selection of bacterial wilt resistance. The chromosome numbers of the fusion parents were confirmed as 24, and the three fusion hybrids crossed were all tetraploids. The chromosome number of 11 backcross 1 progenies (BC1) was 48 and that of the other six was close to the tetraploid number. Backcross 2 progenies (BC2) were obtained from only three of the 44 BC1 clones crossed. The S. commersonii parent clone, LZ3.2, was the most resistant to bacterial wilt among wild species clones tested. The first sexual progenies segregated for resistance, with one clone highly susceptible and four clones highly resistant. Three highly resistant BC1 clones, CT02-4, CT08-4, and CT10b-4, were backcrossed to cultivars. Two cross combinations produced mostly susceptible BC2 progenies; however seven clones were resistant or highly resistant for both race 1 and race 3. The highly resistant three clones, CT204-3, CT206-9 and CT206-10, were selected for the further testing as cultivars or breeding materials.     

病毒病抗性不同的大豆品种及其F_1代过氧化物酶酯酶同工酶分析

本研究对大豆病毒病抗性不同的大豆杂交亲本及F_1代,接种SMV_1号株系后的过氧化物酶和酯酶同工酶的变化进行了分析。结果表明,抗病与感病亲本及其F_1代接种后的同工酶谱带存在着明显的差异。感病亲本及F_1代酶的活性增强,酶带数较多,而且部分酶带变宽,颜色变深。抗病亲本则不发生变化。各组合F_1代的酶谱与双亲有关,抗病×抗病的F_1代酶谱与双亲完全相同,抗病×感病的F_1代酶谱偏向抗性亲本,感病×感病的F_1代产生一个双亲所不具备的小分子新杂种酶带。未接种的感病亲本酶谱与抗病亲本相同。植株内部同工酶的变化与成株抗性相一致。因此,我们认为过氧化物酶同工酶,可作为鉴定大豆抗感病毒病的生化指标之一。