Epistasis and Maternal Effect in Resistance to Puccinia coronata Cda. f. sp. avenae Eriks in Oats （Avena sp.）

The objective of this paper was to investigate the mode of heredity for resistance in oats （Avena sp.） to crown rust caused by Puccinia coronata Cda. f. sp. avenae Eriks, Eight generations of 2 crosses were used to estimate genetic effects and narrow-sense heritability （NSH）. Separate generation means analysis （GMA） indicated a complex gene action controlling this trait with additive, dominance, epistatic and maternal effects （ME）. The genetic model which assumed no epistasis and no ME did not accurately describe the resistance to P. coronata. In both crosses, the digenic epistatic model with ME was sufficient to explain variation in generation means for isolate CRec58 and isolate CRec46. Additive dominance and epistatic components were negative in most cases, suggesting that gene effects contributed more to the resistance than to the susceptibility. The estimated values of NSH were 15-99% depending upon the cross and isolates. The results indicated that appropriate choice of maternal parent and recurrent selection would increase resistance to crown rust in oats.     

Inheritance of Powdery Mildew Resistance in Cucumber （Cucumis sativus L.） and Development of an AFLP Marker for Resistance Detection

Cucumber powdery mildew is one of the most destructive diseases of cucumber throughout the world. In the present study, inheritance of powdery mildew resistance in three crosses, and linkage of resistance with amplified fragment length polymorphism （AFLP） markers are studied to formulate efficient strategies for breeding cultivars resistant to powdery mildew. The joint analysis of multiple generations and AFLP technique has been applied in this study. The best model is the one with two major genes, additive, dominant, and epistatic effects, plus polygenes with additive, dominant, and epistatic effects （E-l-0 model）. The heritabilities of the major genes varied from 64.26% to 97.82%, and susceptibility was incompletely dominant for the two major genes in the three crosses studied. The additive effects of the two major genes and the dominant effect of the second major gene were high, and the epistatic effect of the additive-dominant between the two major genes was the highest in cross I . In cross II, the absolute value of the additive effect, dominant effect, and potential ratio of the first major gene were far higher than those of the second major gene, and the epistatic effect of the additive-additive was the highest. The genetic parameters of the two major genes in cross III were similar to those in cross II. Correlation and regression analyses showed that marker E25/M63-103 was linked to a susceptible gene controlling powdery mildew resistance. The marker could account for 19.98% of the phenotypic variation. When the marker was tested on a diverse set of 29 cucumber lines, the correlation between phenotype and genotype was not significant, which suggested cultivar specialty of gene expression or different methods of resistance to powdery mildew. The target DNA fragment was 103 bp in length, and only a small part was found to be homologous to DNA in the other species evaluated, which indicated that it was unique to the cucumber genome.     

Joint Analysis Method for Major Genes Controlling Multiple Correlated Quantitative Traits

Based on the major gene and polygene mixed inheritance model for multiple correlated quantitative traits, the authors proposed a new joint segregation analysis method of major gene controlling multiple correlated quantitative traits, which include major gene detection and its effect and variation estimation. The effect and variation of major gene are estimated by the maximum likelihood method implemented via expectation-maximization （EM） algorithm. Major gene is tested with the likelihood ratio （LR） test statistic. Extensive simulation studies showed that joint analysis not only increases the statistical power of major gene detection but also improves the precision and accuracy of major gene effect estimates. An example of the plant height and the number of tiller of F2 population in rice cross Duonieai x Zhonghua 11 was used in the illustration. The results indicated that the genetic difference of these two traits in this cross refers to only one pleiotropic major gene. The additive effect and dominance effect of the major gene are estimated as -21.3 and 40.6 cm on plant height, and 22.7 and -25.3 on number of tiller, respectively. The major gene shows overdominance for plant height and close to complete dominance for number of tillers.     

Research of Seed Testa Structure and Storage Material of Peanut Germplasm with Different Resistance to A.flavus

There was an obvious relationship between seed testa structure, storage material and resistance to A. flavus of peanut. Results showed that seed testa of peanut germplasm with high resistance （HR） to A. flavus infection had thicker wax layer, integrated and tight epidermis layer, regular vascular tissue range. However, the seed testa of peanut germplasm with high sensitivity （HS） to A. flavus had the reverse results, and results of those with medium resistance （MR） to A. flavus lay in between, but changes of testa thickness were not significant among different resistance kinds. Results also showed that some seed storage materials were closely related with resistance potential to A. flavus. It seemed that varieties with higher resistance to A. flavus had higher oleic acid and protein content, lower linoleic acid and fat content. Content of palm acid, total sugar and VE did not show positive relationship with the resistance to A. flavus.     

Inheritance Analysis and Identification of SSR Markers Linked to Late Blight Resistant Gene in Tomato

Late blight caused by Phytophthora infestans is the most serious disease of tomato production in China. Studies on the genetics of resistance and identification of molecular markers are very useful for breeding late blight resistant varieties. The objective of this paper was to study the inheritance of late blight resistance and identify simple sequence repeat （SSR） markers associated with resistance allele in tomato （Lycopersicon esculentum Mill）. The results came from an F2 progeny of 241 plants derived from a cross between 5~ inbred line that is susceptible to late blight and a resistant accession CLN2037E. The late blight responses of F2 plants were tested by artificially inoculation of detached-leaflets in plate and natural infection assayed under greenhouse conditions. Both methods showed that the resistance is dominant and inherited as monogenic trait. Genetic mapping and linkage analysis showed that the late blight resistance gene Ph-ROL was located on chromosome 9 with a genetic distance of 5.7 cM to the SSR marker TOM236.     

Analysis of QTLs for the Trichome Density on the Upper and Downer Surface of Leaf Blade in Soybean [Glycine max （L.） Merr.]

Trichomes （plant hairs） are present on nearly all land plants and are known to play important roles in plant protection, specifically against insect herbivory, drought, and UV radiation. The identification of quantitative trait loci （QTL） associated with trichome density should help to interpret the molecular genetic mechanism of soybean trichome density. 184 recombinant inbred lines （RILs）, derived from a cross between soybean cultivars Kefeng 1 and Nannong 1138-2 were used as segregating population for evaluation of TDU （trichome density on the upper surface of leaf blade） and TDD （trichome density on the downer surface of leaf blade）. A total of 15 QTL were detected on molecular linkage groups （MLG） A2, Dla, Dlb, E and H by composite interval mapping （CIM） and among all the QTL, qtuA2-1, qtuD 1 a-1, qtuD lb-2, qtuH-2 qtuE-1, qtdDlb-2, and qtdH- 2 were affirmed by multiple interval mapping （MIM）. The contribution ofphenotypic variance of qtuH-2 was 31.81 and 29.4% by CIM and MIM, respectively, suggesting it might be major gene Ps loci. Only 10 pairs of main QTL interactions for TDU were detected, explained a range of 0.2-5.1% of phenotypic variations for each pair for a total of 22.8%. The QTL on MLG Dlb affecting trichome density were mapped near to Rsc-7 conditioning resistance to SMV （soybean mosaic virus）. This study showed that the genetic mechanism of trichome density was the mixed major gene and polygene inheritance, and also suggested that the causal nature between trichome density and other agronomic traits.     

Resistance identification of bivalent fungi-resistant genes transformed soybean to Phytophthora sojae

Soybean is one of the most important sources of edible oil and proteins in the world.However,it suffers from many kinds of fungal diseases which is a major limiting factor in soybean production.The fungal disease can be effectively controlled by breeding plant cultivars with genetic transformation.In this study,the resistance to Phytophthora sojae of five bivalent transgenic soybean lines was identified using the hypocotyls inoculation technique.The lines were the T,of the transgenic soybean which were transformed with kidney bean chitinase gene and barley ribosome inactivating protein gene,and were positive by Southern Blot analysis.The resistance difference was studied through comparing the death percentage of transgenic soybean with the control.The results showed that four lines were more resistant to P.sojae,whereas other one had no significant difference in comparison with the control.These transgenic soybean lines with enhanced resistance to P.sojae will be useful in soybean resistance breeding.     

Genetic Analysis of Cryotolerance in Cotton During the Overwintering Period Using Mixed Model of Major Gene and Polygene

The joint analysis of the mixed genetic model of major gene and polygene was conducted to study thc inheritance of cryotolerance in cotton during the overwintering period.H077 (G.hirsutum L.,weak cryot...     

Quantitative Trait Loci for Resistance Against Fusarium Wilt Based on Three Cotton F2 Populations

Fusarium wilt （FW） is one of the most common cotton diseases in the world. Identification of QTLs conferring resistance to FW is key for the incorporation of resistance genes into elite cultivars. Two intraspecific （cross between Gossypium hirsuturn L.） and one interspecific （cross between Gossypium hirsutum L. and Gossypium bardence L.） F2 populations were constructed by using a highly resistant cultivar and crossing it to a susceptible cultivar with 154, 79, and 148 offsprings, respectively. Simple sequence repeats （SSR） were used to screen genomic regions closely linked to FW resistance. The results showed that five QTLs associated with FW resistance were detected in two intraspecific populations using a composite interval mapping method under four different conditions. Four of these loci located on Chr. 2/Chr. 17 neighboring markers JESPR304 or CIR305 which explained 13.1 to 45.9% of the phenotypic effect. Furthermore, JESPR304 and CIR305 were previously testified and found to be tightly linked. It is possible that these four QTLs detected under different conditions were the same resistance QTL/gene. We consider that there is the possibility of a major FW resistant gene in intraspecific populations. In the interspecific mapping populations two QTLs were detected on Chr. 9 and Chr. 12/26 which explained great phenotypic variance of 49.4 and 45.7%. As the location of QTLs for FW resistance among the intraspecific and the interspecfic populations were totally different, it is suggested that there may be different resistance mechanisms between G. bardence L. and G. hursutum L. Thus, the present research provides an opportunity to understand the genetic control of resistance to FW in Gossypium hirsutum and Gossypium bardence and to conduct MAS in breeding programs to develop FW resistant cultivars.     

Genetic Analysis and Molecular Mapping of Two SMV-Resistance Traits in Soybean： Adult-Plant Resistance and Resistance to Seed Coat Mottling

Soybean mosaic virus （SMV） could lead to adult-plant system diseases, and cause mottling of soybean seeds. Genetic analysis and molecular mapping were conducted using an F2 population and derived F3 families from two crosses of Dongnong 3C624 （susceptible）x Dongnong 8143 （resistant） and Dongnong 3C628 （susceptible）× Tie 6915 （resistant）. Simple sequence repeat （SSR） markers with bulked segregation analysis （BSA） were used to conduct genetic mapping of the resistance to SMV1 in the segregating populations. The results indicated that resistance to SMV1 in adultplants and the resistance to seed coat mottling in Dongnong 8143 and Tie 6915 was separately controlled by one single dominant gene. The two dominant genes were identified to be linked on the MLG F by Mendel＇s genetics and SSR genetic mapping. The order and distance of markers DPRSMV1 and DSRSMV1 were Sat 229-6.9 cM-DSRSMV1-4.6 cM-Sat_317-3.6 cM-DPRSMV1-5.2 cM-Satt335. The order and distance of markers TPRSMV1 and TSRSMV1 was Satt160-16.1 cM-TPRSMV1-7.3 cM-Satt516-2.0 cM-TSRSMV1-4.5 cM-Sat_133. This research provides the useful information for breeders to select the two types of SMV resistance simultaneously in soybean breeding through molecular marker-assisted selection （MAS）.     

玉米抗黄曲霉菌的基因位点及效应分析

以6个对黄曲霉菌抗性不同的玉米自交系完全双列杂交所获得的6个世代的种子,用黄曲霉菌接种,调查病级,研究玉米抗黄曲霉菌的基因位点及效应.结果表明:参试的6个亲本自交系之间对黄曲霉菌的抗性有较大差异,不同亲本组配的杂种F1对黄曲霉菌的抗感表现不同.各家系的分离群体中抗感个体的分离,少部分呈有规律的分离比例,而大部分组合的分离群体不呈有规律的分离比例,说明玉米对黄曲霉菌的抗性遗传既有主基因效应,也有多基因效应.多基因遗传体系中,既有基因的加性效应、显性效应,还有上位性效应.6个自交系中,可检测到5个对黄曲霉菌有抗性的基因位点,在自交系RA中携带1个效应较大的抗性基因,而其他几个自交系仅携带1～2个效应较小的抗性基因.自交系RA除可用于抗黄曲霉菌玉米新品种的选育,也可用于发展作图群体对玉米抗黄曲霉菌基因进行定位.     

花生含油量杂种优势表现及主基因+多基因遗传效应分析

 【目的】了解是花生遗传改良主要目标含油量的杂种优势和遗传特点,指导花生育种实践。【方法】利用植物数量性状主基因与多基因混合遗传模型的P1、P2、F1、F2 4个世代联合分析方法,分析以花生野生种为高油基因源的4个组合后代群体含油量的遗传效应。【结果】4个组合均存在一定的杂种优势,中亲优势率分别为1.41%～9.42%。不同亲本组合含油量基因遗传特点差异明显。SW9721-3×特21和SW9721-12×濮花22号2个组合分离世代F2含油量次数分布均呈混合正态分布,符合主基因+多基因遗传特征。D-0模型是这2个组合含油量的最佳遗传模型,其含油量遗传受1对加性-显性主基因+加性-显性-上位性多基因控制,主基因遗传率为45.00%～47.51%,多基因遗传率为18.72%～22.75%。SW9721-23×95-3和SW9721-38×鲁花11号2个组合F2含油量次数分布均呈正态分布,符合多基因遗传特征,多基因遗传率为66.09%～66.51%。【结论】花生含油量杂种优势和超亲分离普遍存在;控制含油量性状的基因在效应上存在较大差异,有的出现主基因特性;加性基因在花生含油量遗传中起主要作用,通过高油单株定向选择育种可以实现含油量的有效改良。     

高产陆地棉百棉1号产量性状的主基因+多基因遗传分析

利用高产陆地棉百棉1号为核心亲本分别构建了2个组合的P1、P2、F1、B1、B2和F2群体,应用主基因+多基因遗传模型,研究了陆地棉产量性状的遗传规律。结果表明,2个组合除籽棉产量的最适模型均为D-4(1对负向完全显性主基因+加性-显性多基因模型)外,其他性状最适模型不同,衣分和单株铃数的主基因数目2个组合相同。各产量性状在2个组合中的主基因+多基因遗传方式不尽一致,其中,皮棉产量以主基因遗传为主或以主基因、多基因遗传并重;籽棉产量和籽指以多基因遗传为主或以主基因、多基因遗传并重;衣分、单株铃数、铃重和衣指均以多基因遗传为主;单株生殖量均以主基因遗传为主。2个组合主基因遗传率均为皮棉产量最高,籽棉产量次之,其他性状大小顺序变化差异不大;各产量性状的多基因遗传率在2个组合中的大小顺序变化差异较大。     

西葫芦果肉厚主基因-多基因混合遗传分析

[目的]分析西葫芦果肉厚遗传特性,指导西葫芦果肉厚育种实践。[方法]通过西葫芦自交系配制q-1×23-4G（组合1）和q-1×A-7（组合2）2个组合,构建6个世代群体,应用植物数量性状主基因-多基因混合遗传分析方法,分析不同组合西葫芦果肉厚的遗传表现。[结果]2个组合的西葫芦的果肉厚性状遗传为一对加性主基因＋加性-显性多基因（D-2）遗传模型;2个组合以多基因的显性效应为主;F2的基因遗传率较低,环境影响较高。[结论]西葫芦果肉厚育种宜采用个体选择法,可在晚世代选择。     

作物复交方式复杂遗传模型的构建与扩展

根据广义遗传模型的建模原理,以复交方式的交配设计为基础,扩展了三交和双交组合的加性-显性-上位性模型,包括胚、胚乳、细胞质、母体效应4套遗传体系的种子模型;并系统地构建了三(双)交组合的主基因-多基因混合遗传模型.     

西葫芦果形指数主基因-多基因混合遗传分析

[目的]为西葫芦果形指数育种提供依据。[方法]选用蔓生和矮生的西葫芦自交系配制q-1×23-4G（组合1）和q-1×A-7（组合2）2个组合,构建P1,F1,P2,B1,B2和F26个家系世代群体,应用植物数量性状主基因-多基因混合遗传模型对6个世代群体果形指数进行多世代联合分析。[结果]2个组合的西葫芦果形指数遗传均为1对加性主基因＋加性-显性多基因（D-2）遗传模型,以显性效应为主;2个组合F2的基因遗传率较高,环境影响相对较小。[结论]西葫芦果形指数育种宜早代选择。     

大豆抗烟粉虱的遗传研究

【目的】烟粉虱(Bemisia tabaci Gennadius)是一种严重的灾害性害虫,对大豆的危害也十分严重。了解大豆对烟粉虱抗性的遗传可为大豆抗烟粉虱育种提供参考。【方法】利用高抗烟粉虱种质滑皮豆和高感种质齐黄26,组配了齐黄26×滑皮豆、滑皮豆×齐黄26杂交组合,在山东济南、冠县构建了4个F2遗传群体。调查了各群体和亲本单叶感染烟粉虱的平均数,采用植物数量性状主基因+多基因混合遗传分离分析方法,分析了不同组合、不同地点各遗传群体抗烟粉虱的遗传模式。【结果】不同组合、不同地点的F2群体抗烟粉虱的遗传均符合2对主基因+多基因的混合遗传模式,且主基因的遗传率较高,分别为86.41%、85.72%、95.90%、95.26%;同一组合的F2遗传群体在不同地点抗烟粉虱的遗传模式相同,但主基因遗传率差异较大。【结论】大豆抗烟粉虱既受主基因控制,又存在多基因效应,同时受环境条件影响。改良大豆品种对烟粉虱的抗性应重点利用主基因,同时兼顾多基因的积累。     

西葫芦坐果率主基因-多基因混合遗传分析

[目的]为西葫芦坐果率育种提供依据。[方法]选择坐果率显著不同的西葫芦自交系,配制q-1×23-4G（组合1）和q-1×A-7（组合2）2个组合,通过P1、F1、P2、BC1、BC2和F2六世代联合分析法,研究分析西葫芦坐果率的遗传规律。[结果]2个组合的西葫的加性效应。2个组合F2的基因遗传率较高,环境影响相对较小。[结论]西葫芦坐果率育种宜早代选择。对西葫芦坐果率性状的遗传改良,可选择坐果率较高的亲本材料,通过杂交、回交转移主基因,选育坐果率较高的后代。     

大豆对大豆疫霉根腐病抗性的遗传分析

 【目的】研究大豆对大豆疫霉根腐病完全抗性和部分抗性两种抗性的遗传方式。【方法】利用不同抗性类型的品种（系）配置4个杂交组合,在分别采用下胚轴伤口接种法和根部接种法接种大豆疫霉菌株PNJ1条件下,研究两种抗性的遗传模式。【结果】豫豆25和郑92116对大豆疫霉菌的抗性由一对显性单基因控制,General和 Conrad对大豆疫霉菌的部分抗性由1对加性主基因+加性-显性多基因控制,F2代主基因和多基因遗传率分别为41.31%～74.84%和15.60%～50.36%,F2:3代主基因和多基因遗传率分别为54.21%～77.05%和13.52%～38.24%。大豆对疫霉根腐病完全抗性和部分抗性分别属于不同的遗传体系。【结论】两类抗性都有育种价值,并且在早世代选择是有效的。选育聚合有完全抗性和部分抗性的品种是使大豆获得疫霉根腐病高水平抗性和持久抗性的最佳途径。     

玉米行粒数主基因+多基因混合遗传模型分析

为了对玉米行粒数进行遗传改良,以PH6WC/7873(组合Ⅰ)和MX002/MS001(组合Ⅱ)的6个世代(P1、P2、F1、B1、B2、F2)为材料,利用植物数量性状主基因+多基因混合遗传模型,研究了玉米行粒数的主基因+多基因遗传规律。结果表明,组合Ⅰ的行粒数符合加性-显性-上位性多基因遗传模型(C-0模型)。组合Ⅱ的行粒数符合2对加性主基因+加性-显性多基因遗传模型(E-3模型)。组合Ⅰ3个分离世代的行粒数多基因遗传率分别为75.13%、74.51%、82.59%。组合Ⅱ3个分离世代的行粒数多基因遗传率分别为73.50%、73.20%、72.40%;主基因遗传率分别为6.40%、8.90%、9.10%。以多基因遗传为主,应采用轮回选择和聚合回交的方法积累微效基因,对玉米行粒数进行遗传改良。