Identificaiton of a clubroot resistance locus conferring resistance to a Plasmodiophora brassicae classified into pathotype group 3 in Chinese cabbage (Brassica rapa L.)

In Chinese cabbage (Brassica rapa), the clubroot resistance (CR) genes Crr1 and Crr2 are effective against the mild Plasmodiophora brassicae isolate Ano-01 and the more virulent isolate Wakayama-01, but not against isolate No. 14, classified into pathotype group 3. ‘Akiriso’, a clubroot-resistant F₁ cultivar, showed resistance to isolate No. 14. To increase the durability of resistance, we attempted to identify the CR locus in ‘Akiriso’. CR in ‘Akiriso’ segregated as a single dominant gene and was linked to several molecular markers that were also linked to CRb, a CR locus from cultivar ‘CR Shinki’. We developed additional markers around CRb and constructed partial genetic maps of this region in ‘Akiriso’ and ‘CR Shinki’. The positions and order of markers in the genetic maps of the two cultivars were very similar. The segregation ratios for resistance to isolate No. 14 in F₂ populations derived from each of the two cultivars were also very similar. These results suggest that the CR locus in ‘Akiriso’ is CRb or a tightly linked locus. The newly developed markers in this study were more closely linked to CRb than previously reported markers and will be useful for marker-assisted selection of CRb in Chinese cabbage breeding.     

Combination of resistance to Verticillium longisporum from zero erucic acid Brassica oleracea and oilseed Brassica rapa genotypes in resynthesized rapeseed (Brassica napus) lines

Resynthesized (RS) forms of rapeseed (Brassica napus L.; genome AACC, 2n = 38) generated from interspecific hybridization between suitable genotypes of its diploid progenitors Brassica rapa L. (syn. campestris; genome AA, 2n = 20) and Brassica oleracea L. (CC, 2n = 18) represent a potentially useful resource to introduce resistance against the fungal pathogen Verticillium longisporum into the gene pool of oilseed rape. Numerous cabbage (B. oleracea) accessions are known with resistance to V. longisporum; however, B. oleracea generally has high levels of erucic acid and glucosinolates in the seed, which reduces the suitability of resulting RS rapeseed lines for oilseed rape breeding. In this study resistance against V. longisporum was identified in the cabbage accession Kashirka 202 (B. oleracea convar. capitata), a zero erucic acid mutant, and RS rapeseed lines were generated by crossing the resistant genotype with two spring turnip rape accessions (B. rapa ssp. olerifera) with zero erucic acid. One of the resulting zero erucic acid RS rapeseed lines was found to have a high level of resistance to V. longisporum compared with both parental accessions and with B. napus controls. A number of other zero erucic acid RS lines showed resistance levels comparable to the parental accessions. In the most resistant RS lines the resistance and zero erucic acid traits were combined with variable seed glucosinolate contents. Erucic acid‐free RS rapeseed with moderate seed glucosinolate content represents an ideal basic material for introgression of quantitative V. longisporum resistance derived from B. oleracea and B. rapa into elite oilseed rape breeding lines.     

Disease response of resynthesized Brassica napus L. lines carrying different combinations of resistance to Plasmodiophora brassicae Wor.

Resistance responses of resynthesized Brassica napus lines to infection with Plasmodiophora brassicae were investigated. Lines that were derived from interspecific crosses between clubroot-resistant B. rapa and resistant B. oleracea exhibited very broad and effective resistance in both greenhouse and field tests. When clubroot resistance was introduced into resynthesized lines from the B. oleracea parent only, the plants were mainly susceptible. Interspecific hybrids from the most resistant parental genotypes, i.e. B. campestris ECD-04 and the B. oleracea cultivars ECD-15 or ‘Bohmerwaldkohf’, were used to initiate a B. napus resistance-breeding programme. These artificial rapeseed lines were resistant to isolates that were virulent on all B. napus differential lines and/or parental lines. Preliminary segregation analysis suggests that their resistance is due to at least two dominant and unlinked genes. In some cases progenies from selfed resynthesized plants exhibited resistance reactions that differed from those of the parental hybrid plant; this may have been the result of cytological instability.     

Novel pathotypes of lettuce mosaic virus — breakdown of a durable resistance?

Summary Resistance to lettuce mosaic virus (LMV) is derived either from cv. Gallega (g gene) or the wild accession PI251245 (mo gene). Previous studies indicated that these two genes were identical. Breeders in Europe produced numerous resistant cultivars utilisingg while in the USAmo was used. The resistance has been effective for over 20 years. However, recently there have been reports of LMV isolates causing unusually severe and sometimes necrotic symptoms on cultivars with these resistance genes. Investigations of these severe isolates have distinguished three new pathotypes in addition to the common pathotype (II) and identified a novel dominant gene for resistance. Themo/g genes confer resistance to pathotypes I and II but pathotype III possesses virulence for cultivars withg but not for those withmo. These two genes are therefore not identical but are probably either closely linked genes or alleles. Pathotype IV possesses virulence for all lettuce lines so far tested. Some isolates of this pathotype are seed transmitted in cultivars possessingmo org and have caused severe crop losses in southern France. The durability of the resistance conditioned by these two genes is discussed.     

DNA markers linked to Pga1, an adzuki bean gene that confers resistance to Cadophora gregata race 1

Brown stem rot (BSR) caused by Cadophora gregata f. sp. adzukicola (syn. Phialophora gregata) is a serious soilborne disease of adzuki bean (Vigna angularis) in Japan. Cultivation of resistant cultivars is the most effective disease control method, therefore the selection of resistant lines is a priority for breeders. BSR-resistant adzuki bean lines have been screened in pathogen-infected fields. However, field selection using the pathogen and artificial inoculation methods is time-consuming and labor-intensive. In the present study, we used 105 F₃ lines derived from a cross between a BSR-resistant cultivar ‘Syumari’ and a susceptible cultivar ‘Buchishoryukei-1’ for BSR inoculation tests. Amplified fragment-length polymorphism (AFLP) analyses with 1024 primer sets revealed that six fragments were polymorphic between resistance and susceptible bulked groups. Five DNA markers (Pg77, Pg118, Pg138, Pg139 and Pg126) were developed from the nucleotide sequences of polymorphic AFLP markers and their flanking regions. Pg118, which was derived from E-ACT/M-ACT-118, was tightly linked to the resistance gene Pga1 and was converted into a codominant marker for its easier use in marker-assisted selection for adzuki bean BSR resistance. Finally, the applicability of the developed markers for BSR resistance was tested on 32 adzuki bean accessions or cultivars.     

Breeding of cabbage (Brassica oleracea L. var. capitata) with fusarium wilt resistance based on microspore culture and marker-assisted selection

Cabbage Fusarium wilt (CFW), caused by Fusarium oxysporum f. sp. conglutinans, is one of the most devastating diseases of cabbage worldwide. In recent years, CFW has been spreading across northern Chinad. Thus, development of resistant cultivars is necessary to control CFW. Here we report microspore culture from a cross of two elite cabbage inbred lines, 96–100 (highly resistant to CFW) and 01–20 (highly susceptible to CFW), in order to obtain doubled haploids (DHs) to cultivate cabbage materials for resistance breeding. A total of 196 DHs were obtained in 2011 and 2012 and three elite DH lines were selected from them through agronomic trait evaluation as well as marker-assisted selection. These three elite DH lines were crossed with elite cabbage inbred lines to create hybrids, which were then evaluated for their resistance and agronomic traits. Three excellent hybrids were selected. The use of microspore culture and marker-assisted selection greatly shortened the time required to obtain these excellent hybrids. These resistant varieties may become an effective control of CFW in diseased areas.     

Marker-assisted selection of low erucic acid quantity in short duration Brassica rapa

Low erucic acid (LEA) rapeseed, which has accumulated mutant fatty acid elongase genes at the BnFAE1.1 and BnFAE1.2 loci of the A- and C-genome, respectively, is an important oilseed crop. Short growing turnip rape (B. rapa) is also important as a catch crop in the continuous cropping of rice in Asia but there is no LEA B. rapa cultivar for cultivation in South Asia. In order to develop LEA turnip rape cultivars, high erucic acid turnip rape cultivars were interspecifically crossed as recurrent parents to a canola quality rapeseed. In the meantime, we monitored incorporation of the mutant bnfae1.1 (e1) gene into A-genome of turnip rape, using a dCAPS primer pair, which can amplify PCR fragment only for the mutant e1 gene from A-genome. The early backcross progenies showed poor seed set, but which was improved in advanced progenies. Finally, homozygous e1e1 genotypes were established in the selfed progenies of BC₂–BC₃, and their LEA content was confirmed by gas-chromatography analysis. Our results and promising lines will contribute to LEA-trait selection in turnip rape and rapeseed breeding.     

油菜感抗品种混播对根肿病防控效果的影响

近年来,油菜根肿病危害在我国呈蔓延趋势,主要原因是化学防治成本高且效果差。实际生产中,种植抗性品种是最经济、最有效的措施。不同抗感品种混播,在保证产量稳定的前提下可减轻对病原菌小种的选择压,从而稳定病原菌种群结构,延长抗性品种使用寿命。本试验在安徽绩溪、云南临翔2个油菜根肿病严重发生区域,选择2组互为近等基因系的感病、抗病的油菜品种,按不同比例混播(感病、抗病比例分别为10:0、1:9、2:8、3:7和0:10),在根肿病明显发生后调查发病率等指标。结果表明:不同比例感病、抗病油菜品种混播均降低了根肿病发病率和病情指数,并稳定油菜产量和品质;且油菜发病株率随抗病品种的比例下降而升高,但均低于理论发病率;不同抗性组合间混播的相对防效(REM)均低于1,且随着作物生育期的推迟呈现下降趋势。以上结果表明,油菜感抗品种混播对根肿病有较好的防控效果。本研究主要在大田条件下明确了2组不同抗感近等基因组合混播对油菜根肿病的防治效果,可为油菜根肿病防治提供思路和对策。     

西南地区油菜品种根肿病抗性及布局分析

为明确西南地区主栽油菜品种根肿病抗性,以期为合理品种布局提供依据,降低根肿病的危害和损失。结合病圃根肿病菌生理小种鉴定,在四川安县、大邑、广汉三地区,采用病圃自然发病法,对80个油菜品种进行根肿病抗性评价,并对22个品种连续3年进行抗性跟踪。结果表明：三地区病圃根肿菌为存在基因型分化的4号生理小种;供试油菜品种中无免疫根肿病品种,安县、大邑、广汉三地感病品种分别占比88.75%、83.75%、87.50%,其中55个品种在三地区均表现感病,即不适宜在根肿病菌为4号生理小种区域种植;抗性跟踪评价显示不同品种的抗性稳定性存在差异。‘浙油50’、‘油罐罐’适宜安县地区种植,‘黄金荚’、‘金油858’、‘油研9号’、‘种都油998’和‘渝黄4号’适宜大邑地区种植,‘志远油8号’适宜广汉地区种植。‘绵丰油5号’、‘德名油1号’表现抗性丧失趋势;‘丰油精’、‘高油48’抗性不稳定;‘矮架早’抗性完全丧失。     

Screening and genetic analysis of resistance to peanut stunt virus in soybean: identification of the putative Rpsv1 resistance gene

The peanut stunt virus (PSV) causes yield losses in soybean and reduced seed quality due to seed mottling. The objectives of this study were to determine the phenotypic reactions of soybean germplasms to inoculation with two PSV isolates (PSV-K, PSV-T), the inheritance of PSV resistance in soybean cultivars, and the locus of the PSV resistance gene. We investigated the PSV resistance of 132 soybean cultivars to both PSV isolates; of these, 73 cultivars exhibited resistance to both PSV isolates. Three resistant cultivars (Harosoy, Tsurunotamago 1 and Hyuga) were crossed with the susceptible cultivar Enrei. The crosses were evaluated in the F₁, F₂ and F_2:3 generations for their reactions to inoculation with the two PSV isolates. In an allelism test, we crossed Harosoy and Tsurunotamago 1 with the resistant cultivar Hyuga. The results revealed that PSV resistance in these cultivars is controlled by a single dominant gene at the same locus. We have proposed Rpsv1, as the name of the resistance gene in Hyuga. We also constructed a linkage map using recombinant inbred lines between Hyuga × Enrei using 176 SSR markers. We mapped Rpsv1 near the Satt435 locus on soybean chromosome 7.     

感抗油菜近等基因系混播对根肿病发病率的影响

近年来,根肿病的迅速蔓延已对我国油菜生产造成严重威胁。课题组前期多年多点大田试验发现,感病、抗病品种混播可显著降低感病油菜品种根肿病发病率。为进一步探究感病、抗病品种播种间距对根肿病的防控效果,本试验采用穴盘栽培,设置感、抗根肿病油菜近等基因系不同播种间距(0、2、4、6 cm),出苗后7 d接种根肿菌,接种42 d后调查幼苗发病率、病情指数,并测定根系主要成分。结果表明:(1)与单播相比,感病、抗病品种同播时,抗病品种苗期发病率无明显变化,而感病品种苗期发病率显著下降,其发病率与感病、抗病品种播种间距密切相关,二者距离为0 cm时的发病率及病情指数均显著(P0.05)低于其他处理;(2)与单播相比,感病、抗病品种同播时,抗病品种和感病品种根中可溶性糖及可溶性蛋白质含量均显著降低,酸不溶木质素含量在感病品种中显著增加,而在抗病品种中呈现先增加后降低的趋势;(3)发病率和病情指数均与根系可溶性糖和可溶性蛋白质含量显著正相关(P0.01),发病率与可溶性糖和可溶性蛋白质含量的相关系数分别为0.797、0.403,病情指数与可溶性糖和可溶性蛋白质含量的相关系数分别为0.822、0.509。综上,油菜感、抗品种混播可以显著降低感病品种的根肿病发病率,且混播间距在0 cm时效果最好。该技术可以作为油菜根肿病防控的技术措施,在根肿病发病区域油菜生产上有着较好的应用前景。     

油菜抗咪唑啉酮类除草剂基因BnALS1R等位基因特异PCR标记的开发与应用

油菜抗咪唑啉酮类除草剂基因BnALS1R是从抗性突变体M9中克隆获得,抗性基因BnALS1R与野生型基因BnALS1存在1处SNP,即乙酰乳酸合酶第638位丝氨酸残基被天冬酰胺酸替代。为获得油菜抗除草剂基因BnALS1R的分子标记,根据该处点突变,结合获得的BnALS3与BnALS1序列,开发30条等位基因特异PCR (allele-specific PCR,AS-PCR)引物,采用筛选出的3条AS-PCR引物在F₂、BC₁和BC₂群体中进行PCR扩增。结果表明,该标记有效检测出群体中存在的3种基因型,其分离比分别为1∶2∶1、1∶1、1∶1,均遵循单基因遗传规律。应用该标记对获得的抗性恢复系进行PCR扩增,结果发现所有抗性恢复系均能扩增出抗性基因BnALS1R目的条带,表明3条标记引物可应用于抗性基因的检测。AS-PCR标记的获得将促进以抗性基因进行油菜抗除草剂分子标记辅助选择育种。     

Identification and validation of a quantitative trait locus associated with wheat yellow mosaic virus pathotype I resistance in a Japanese wheat variety

Yellow mosaic disease, caused by wheat yellow mosaic virus (WYMV), is one of the most serious diseases of winter wheat (Triticum aestivum L.) in Japan. The three pathotypes of WYMV are distributed in different geographical areas: pathotype I is found mainly in western and central Japan (Kanto), pathotype II in northern Japan (Tohoku and Hokkaido) and pathotype III on the southern island of Japan (Kyushu). A total of 246 doubled‐haploid (DH) lines, derived from a cross between ‘Yumechikara’ (resistant) and ‘Kitahonami’ (susceptible), were evaluated for 2 years for their resistance to WYMV pathotype I. A single major quantitative trait locus, Q.Ymym, mapping to chromosome 2D was associated with resistance to pathotype I in ‘Yumechikara’. This is the first time a QTL responsible for pathotype I resistance has been identified. Fine mapping of Q.Ymym indicated that it was on a tight linkage block originating from ‘Yumechikara’, and the markers associated with this block will accelerate the development of varieties resistant to WYMV pathotype I.     

Genetic analysis and identification of DNA markers linked to a novel Phytophthora sojae resistance gene in the Japanese soybean cultivar Waseshiroge

The Glycine max (L.) Merr. cultivar Waseshiroge is highly resistant to several races of Phytophthora sojae in Japan. In order to determine which Rps gene might be present in Waseshiroge, 15 differential cultivars were challenged with 12 P. sojae isolates. None had a reaction pattern identical to that of Waseshiroge, indicating that Waseshiroge may contain a novel Rps gene. In order to characterize the inheritance of Waseshiroge resistance to P. sojae isolates, 98 F₂ progeny and 94 F_7:8 lines were produced from crosses between the susceptible cultivar Tanbakuro and Waseshiroge. Chi-square tests indicated that segregation fit a 3:1 ratio for resistance and susceptibility in two F₂ sub-populations of 42 and 56 seedlings. This and a 46.27:1.46:46.27 (or 63:2:63) ratio for resistance: segregation: susceptibility among the 94 F_7:8 lines indicated that resistance was controlled by a single dominant gene. DNA analyses were carried out on Tanbakuro, Waseshiroge and the 94 F_7:8 lines, and a linkage map was constructed with 17 SSR markers and nine new primer pairs that amplify marker loci linked to Rps1 on soybean chromosome 3 (linkage group N). The closest markers, Satt009 and T000304487l, map to locations 0.9 and 1.6 cM on each side of the estimated position of the Rps gene, respectively. The results showed that the Rps gene in Waseshiroge is either allelic to Rps1, or resides at a tightly linked locus in a gene cluster. A three-way-contingency table analysis indicated that marker-assisted selection with the two flanking markers could be used in the development of new resistant cultivars.     

工业专用型高芥酸油菜新品种选育

高芥酸油菜品种是在工业上具有广泛用途的专用型品种。本研究通过两个常规芥酸品种杂交,采用以单株和单粒筛选相结合对芥酸含量正向选择为核心的技术,育成了芥酸含量达60%的甘蓝型高芥酸油菜新品种高芥1号。同时阐明了在高芥酸含量背景下各种脂肪酸间的相关性,为相关育种提供了—些理论依据。     

Development of an SSR marker set for efficient selection for resistance to black spot disease in pear breeding

Black spot disease, which is caused by Alternaria alternata (Fries) Keissler Japanese pear pathotype, is one of the most harmful diseases in Japanese pear cultivation. Because of the potential harm of fungicides to consumers and the environment, resistant cultivars are desired. In this study, to enable efficient marker-assisted selection in pear breeding, we conducted comprehensive inoculation tests and genotyping with 207 pear cultivars. We identified a marker set (Mdo.chr11.27 and Mdo.chr11.34) suitable for selection for black spot resistance. In most susceptible cultivars, Mdo.chr11.27 amplified a 220-bp band and Mdo.chr11.34 amplified a 259-bp band. The genotype of Mdo.chr11.34 corresponds perfectly to the estimated genotype of Japanese pears susceptible to black spot disease. Using linkage analysis, we identified the positions of the gene for susceptibility to black spot disease in Chinese pear. Mdo.chr11.27 and Mdo.chr11.34 were tightly linked to susceptibility in Chinese pear, and the susceptibility gene was mapped at the top of linkage group 11, similar to that in Japanese pear. This marker set and the accumulation of phenotypic data will enable efficient marker-assisted breeding for black spot resistance in pear breeding.     

A survey of soybean germplasm for resistance to <Emphasis Type="Italic">Phytophthora sojae</Emphasis>

Phytophthora root and stem rot of soybean caused by Phytophthora sojae is a destructive disease affecting soybean production regions throughout the world. The utilization of resistant cultivars is the most economical and environmentally safe method for controlling this disease. This work aims to screen the effective sources of special and partial resistance for the development of resistant cultivars. A total of 611 soybean germplasm lines from three ecological regions were evaluated for their responses to three P. sojae strains, namely, PNJ1, PNJ3, and PNJ4, using the hypocotyl inoculation technique. The soybean germplasm lines elicited eight different reaction types with three strains. Among these, 106 were resistant and 253 were susceptible to the three strains. A total of 123 soybean germplasm lines identified as susceptible to the three strains by the hypocotyl inoculation method were evaluated for partial resistance to PNJ1 using the slant board assay. Thirty-nine cultivars displayed high levels of partial resistance to PNJ1. The results of this study can be utilized to plant appropriately resistant cultivars in infected fields and to provide good breeding materials.     

Evaluation of French Brassica oleracea landraces for resistance to Plasmodiophora brassicae

A total of 240 kale, 38 cabbage and 126 winter cauliflower French landraces from the B. oleracea genepool of INRA were assessed for resistance to clubroot caused by Plasmodiophora brassicaeWoron. Two French isolates of the pathogen (K and SJ) were used in the experiments under controlled conditions. The reaction of the 126 cauliflower accessions to naturally occurring clubroot was also evaluated in field trials. Kales exhibited considerable variation for expression of disease resistance and high levels of resistance were found in several accessions. In this group, single resistant plants were observed in most of the morphological types and from quite different geographical origins. Cabbage accessions were moderately to highly susceptible to both isolates. All cauliflower populations proved to be highly susceptible to K isolate and moderately susceptible to SJ isolate. In field trials, cauliflowers were also severely infected. Two lines selected from a resistant kale population were highly resistant against a large range of pathotypes of the pathogen. These lines presented a sufficient level of resistance to be directly useful in the breeding program in order to develop cauliflower and broccoli hybrids resistant to clubroot. This revised version was published online in July 2006 with corrections to the Cover Date.     

近10年我国冬油菜区试品种品质及产量性状的演变分析

油菜是我国最重要的食用油料作物。本文综合分析了2000年～2009年10个年度国家冬油菜区域试验参试品种的品质及产量性状。分析表明：2002年是我国油菜品种品质（低芥酸、低硫苷）和产量的转折点,此后双低油菜品种比例在80%以上,产量也逐步提高,到目前基本达到双高品种的产量水平。分析表明双低油菜产量的提高,主要归因于单株结角数和千粒重的增加;此外,双低油菜品种含油量有了较大的突破,尤其是近3年含油量有了显著提高。这表明在我国油菜品种双低化过程中,品质和产量得到了协同发展。目前在双低品质达标的情况下,提高产量和含油量仍是我国油菜育种的主攻目标。     

Inheritance of resistance to angular leaf spot in common bean and validation of the utility of resistance linked markers for marker assisted selection out side the mapping population

Inheritance of resistance to angular leaf spot (ALS) disease caused by Phaeoisariopsis griseola (Sacc.) Ferr was investigated in two common bean cultivars, Mexico 54 and BAT 332. Both Andean and Mesoamerican backgrounds were used to determine the stability of the resistance gene in each of the two cultivars. Resistance to P. griseola was phenotypically evaluated by artificial inoculation with one of the most widely distributed pathotypes, 63–39. Evaluation of the parental genotypes, F₁, F₂ and backcross populations revealed that the resistance to angular leaf spot in the cultivars Mexico 54 and BAT 332 to pathotype 63–39 is controlled by a single dominant gene, when both the Andean and Mesoamerican backgrounds were used. Allelism test showed that ALS resistance in Mexico 54 and BAT 332 to pathotype 63–39 was conditioned by the same resistance locus. Resistant and susceptible segregating populations generated using Mexico 54 resistant parent were selected for DNA extraction and amplification to check for the presence /absence of the SCAR OPN02 and RAPD OPE04 markers linked to the Phg-2 resistance gene. The results indicated that the SCAR OPN02 was not polymorphic in the study populations and therefore of limited application in selecting resistant genotypes in such populations. On the other hand, the RAPD OPE04 marker was observed in all resistant individuals and was absent in those scored susceptible based on virulence data. Use of the RAPD OPE04 marker in marker-assisted selection is underway.