Genetic Characterization of Differential Reactions Among Host Group 3 Common Bean Cultivars to NL-3 K Strain of Bean common mosaic necrosis virus

ABSTRACT A previously unrecognized recessive resistance gene (or allele) was identified in three host group (HG) 3 common bean (Phaseolus vulgaris) cvs. Olathe, Victor, and UI 37, based on genetic analysis of plants from five populations screened with the NL-3 K strain of Bean common mosaic necrosis virus (BCMNV). The gene (or allele) was associated with resistance to leaf stunting and deformity and reduction in plant height. The gene (or allele) provides similar, but slightly better resistance than the bc-1(2) gene that is characteristic of HG 3 cultivars. Traditional HG 3 cultivars like Redlands Greenleaf B with bc-1(2) are susceptible to NL-3 K, whereas this newly identified gene (or allele) conditions resistance to NL-3 K. Other slight variations in disease reaction pattern to a wide array of bean common mosaic (BCM)-inducing strains were noted among HG 3 differentials, indicating that additional resistance to BCM exists in common bean that remains to be exploited. To gauge the full breeding value of this newly identified gene (or allele), allelism tests with existing genes, namely bc-1(2), and further characterization of responses to all Bean common mosaic virus (BCMV) and BCMNV strains need to be conducted. Meanwhile, breeders should consider introgressing this more effective gene (or allele) into susceptible cultivars while plant pathologists continue to decipher the genetic variability present among HG 3 differential cultivars.     

Elimination of Bean common mosaic virus using an electrotherapy technique

Journal of Plant Diseases and Protection - Bean common mosaic virus (BCMV) is a major seed transmitted virus of common bean (Phaseolus vulgaris). The use of virus-free germplasm is a prerequisite...     

The occurrence of bean common mosaic necrosis virus in wild and forage legumes in Uganda

Bean common mosaic necrosis virus (BCMNV) was isolated from Centrosema pubescens, Crotalaria incana, Lablab purpureus, Phaseolus lunatus, Senna bicapsularis, S. sophera, Vigna vexillata and an unidentified Crotalaria species growing in Uganda. Thirteen distinct isolates were characterized using symptoms, pathogenicity in differential bean cultivars, serology, immunosorbent electron microscopy, and seed and aphid transmission. Some isolates conformed with the characteristics of previously described strains of BCMNV but others showed novel properties. All isolates reinfected the natural host from which they were obtained. The origin and ecological significance of these isolates is discussed.     

菜豆普通花叶病毒RT-PCR承检测及3'末端序列分析

根据哈尔滨地区豇豆感病植株的症状,初步鉴定感染豇豆的病毒为菜豆普通花叶病毒(Bean common mosaic virus,BCMV).利用马铃薯Y病毒属通用引物扩增出病毒基因组3'末端序列,经BLAST检索表明该病毒为BCMV,将该序列与GenBank上的21个BCMV分离物的3'末端序列进行比较,显示其核苷酸序列与其他分离物的序列同源性为91.7%～97.3%.系统进化分析显示不同分离物可聚为5个类群,并显示出一定的寄主相关性.哈尔滨分离物BCMV-X与2个浙江分离物、1个澳大利亚分离物聚为一支,且该4株分离物的寄主均为豇豆.RNA二级结构分析显示BCMV基因组3'末端非编码区形成4个茎环结构,不同分离物的序列变化并未引起茎环结构的明显变化.     

Characterization of <Emphasis Type="Italic">Bean common mosaic virus</Emphasis> and <Emphasis Type="Italic">Bean common mosaic necrosis virus</Emphasis> isolates in common bean growing areas in Turkey

Bean common mosaic virus (BCMV) and Bean common mosaic necrosis virus (BCMNV) are well-known legume-infecting potyviruses. The incidences of BCMV and BCMNV infections were determined by ELISA in 367 seed and leaf samples which were collected in 15 common bean-growing provinces of Turkey. Of the samples tested, 67 (18.2 %) occurred to be infected with BCMV, however only 5 (1.4 %) were infected with BCMNV. A total of 45 ELISA-positive samples were selected from single-virus infected ones to determine BCMV and BCMNV pathogenicity groups (PGs) by using a set of bean cultivars that contain different combinations of resistance genes. Some BCMV populations exhibiting unusual pathogenicity were identified. One of them, named TR-180, was found to overcome resistance conferred by bc-1, bc-1 ² , bc-2 and bc-2 ² recessive alleles in common bean and assigned to PG VII. This isolate shared high (99 %) sequence identity with previously identified BCMV RU-1 and RU-1-related strains (RU1-OR-B and RU1-OR-C) according to a BLAST analysis of the nucleotide sequences of RT-PCR amplified products comprising the complete coat protein and 3′ partial NIb regions. The isolates TR-203 and TR-256 produced a distinctive reaction pattern in the dominant I gene-bearing bean cultivars Amanda and Isabella at lower (<30 °C) temperatures and were classified into PG IVb. These isolates were found to be 99 % identical to US-1 strain based on 3′ terminal nucleotide sequences of the BCMV genome. A fourth isolate, TR-243, involved mixed BCMV populations, as confirmed by partial nucleotide sequence analysis; one was classified as belonging to PG VII being similar to TR-180, and another was assigned to PG IVb. In conclusion, on the basis of both the reactions of differential bean cultivars and ELISA results, most of BCMV isolates were assigned to pathogroup PG VII and BCMNV isolates to PG VIb. This study is the first to show that four recessive resistance alleles of common bean can be overcome by a single field isolate of BCMV, and that a wide range of BCMV pathogroups are present in Turkey.     

Pathogenic and coat protein characterization confirming the occurrence of Bean common mosaic virus on common bean (Phaseolus vulgaris) in Kashmir,India

Bean common mosaic virus (BCMV), belonging to the family Potyviridae, is a serious pathogen of common bean (Phaseolus vulgaris L.) causing considerable economic losses owing to seed, sap and aphid transmissibility. The viral nature of the test isolates and identity of the virus as BCMV were confirmed by mechanical transmission and DAS-ELISA using BCMV antiserum. Pathogenic variability studies in BCMV infecting common bean (Phaseolus vulgaris L.) in Jammu and Kashmir (a northwestern Himalayan state of India), revealed the existence of three pathogroups – PG-I, PG-II and PG-VII, accommodating five strains (NL-1, NL-1n, NL-4, NL-7 and NL-7n). Comparative sequence analysis of coat protein gene revealed that the strains NL-1, NL-4 and NL-7 shared more than 90% amino acid sequence homology with other BCMV isolates from other countries. DAG motif as well as BCMV specific conserved motif MVWCIDN were present in all the three strains. Phylogenetic analysis of coat protein also clustered them in the BCMV group. This study confirmed the occurrence of BCMV and its strains on common bean in Kashmir.     

Identification of Resistance to Common Bacterial Blight Disease on Bean Genotypes Grown in Turkey

Common bacterial blight (CBB) in edible beans (Phaseolus vulgaris), incited Xanthomonas campestris pv. phaseoli, reduces bean yields and seed quality. The main objective of this study was to determine resistance to common bacterial blight in bean genotypes. Twenty-two bean genotypes grown in Turkey including common and snap bean cultivars/lines were collected from different parts of Turkey and tested for resistance against to Xanthomonas campestris pv. phaseoli strain MFD-11. All the common and snap bean lines/cultivars tested were moderately susceptible, susceptible or highly susceptible, except AG-7117 which was found resistant to Xanthomonas campestris pv. phaseoli. This is the first report of a resistance source in a common bean line (AG-7117) against Xanthomonas campestris pv. phaseoli.     

Genetic aspects of polyacrylic-acid-induced resistance to tobacco mosaic virus and tobacco necrosis virus in Nicotiana plants

Among the Nicotiana tabacum cultivars and hybrids tested, polyacrylic acid (PAA) only induced resistance to tobacco mosaic virus (TMV) and tobacco necrosis virus (TNV) in the cultivars Xanthi-nc (NN) and Xanthi (nn) respectively. This varietal response to the PAA treatment could be sexually transmitted. The complete genetic analysis of the inheritance of the PAA response is reported for the first time, demonstrating that the response is a dominant character with a Mendelian segregation which occurs independently of either the N gene responsible for resistance to TMV or the PRb-protein genes. Possible relationships between the N gene, the gene for the PAA response and the PRb genes are discussed.     

Quantitative trait Loci mapping of resistance to sugarcane mosaic virus in maize

ABSTRACT Sugarcane mosaic virus (SCMV) is an important virus disease of maize (Zea mays) in Europe. In this study, we mapped and characterized quantitative trait loci (QTL) affecting resistance to SCMV in a maize population consisting of 219 F(3) or immortalized F(2) families from the cross of two European maize inbreds, D32 (resistant) x D145 (susceptible). Resistance was evaluated in replicated field trials across two environments under artificial inoculation. The method of composite interval mapping was employed for QTL detection with a linkage map based on 87 restriction fragment length polymorphism and 7 mapped microsatellite markers. Genotypic and genotype x environment interaction variances for SCMV resistance were highly significant in the population. Heritabilities ranged from 0.77 to 0.94 for disease scores recorded on seven consecutive dates. Five QTL for SCMV resistance were identified on chromosomes 1, 3, 5, 6, and 10 in the joint analyses. Two major QTL on chromosomes 3 and 6 were detected consistently in both environments. Significant epistatic effects were found among some of these QTL. A simultaneous fit with all QTL in the joint analyses explained between 70 and 77% of the phenotypic variance observed at various stages of plant development. Resistance to SCMV was correlated with plant height and days to anthesis.     

Generation and Molecular Mapping of a Sequence Characterized Amplified Region Marker Linked with the Bct Gene for Resistance to Beet curly top virus in Common Bean

ABSTRACT A random amplified polymorphic DNA (RAPD) marker directly linked (0.0 cM) with a resistance gene was identified in a snap bean recombinant inbred population (Moncayo x Primo) consisting of 94 F(5:7) recombinant inbred lines that had uniform segregation for disease reaction to Beet curly top virus (BCTV) across three field locations. Resistance was conditioned by a single dominant allele tentatively designated Bct. Seven hundred and fifty decamer primers were screened to obtain the linked RAPD marker that was then converted to a sequence characterized amplified region (SCAR) marker SAS8.1550. The SCAR mapped within a cluster of resistance genes on linkage group B7 of the core map. A survey of 103 BCTV-resistant and -susceptible snap and dry bean genotypes was conducted using SAS8.1550. Results showed that the SCAR would be highly useful for marker-assisted selection of Bct in snap and dry bean originating from the Andean gene pool. Marker-assisted selection for Bct will expedite the development of BCTV-resistant cultivars and minimize the need for cumbersome pathogen tests.     

Resistance of Capsicum species to tobacco,tomato and pepper strains of tobacco mosaic virus

A number ofCapsicum accessions including nine species were tested for resistance to TMV based on hypersensitivity. The tobacco strain MA and the tomato strain SPS, which were both isolated from tomato, and two pathogenically distinct pepper strains P 11 and P 8, were used. Of the 73Capsicum accessions tested 58 were resistant to MA and SPS, 31 were resistant to P 11 and five were resistant to P 8.Samenvatting Om verschillen in pathogeniteit tussen twee in Nederland voorkomende paprikastammen van het TMV nader vast te stellen, werd een aantalCapsicum-herkomsten, waaronder negen soorten, op resistentie getoetst. Hierbij werden de representatieve paprika-isolaten P 11 en P 8 vergeleken met de uit tomaat afkomstige isolaten MA en SPS als vertegenwoordigers van respectievelijk de tabaks- en tomatestam van het TMV. Bij het beoordelen van de symptomen duidden lokale, necrotische vlekken en afvallen van geïnoculeerde bladeren op resistentie, systemische necrosen of mozaïeksymptomen op vatbaarheid. In deze symptomen kwamen tussen de gebruikte stammen verschillen in virulentie tot uitdrukking. Er werden echter vooral verschillen in agressiviteit waargenomen met betrekking tot zowel afzonderlijke, voor resistentie uitsplitsende,Capsicum-herkomsten als het totale aantal getoetste herkomsten. Van de ruim 73 herkomsten waren er 58 resistent tegen MA en SPS, 31 daarvan tegen P 11, maar slechts vijf daarvan tegen P 8. Deze resistentie tegen P 8 werd gevonden inC. chinense.     

A transgenic RNAi approach for developing tomato plants immune to Pepino mosaic virus

RNA interference (RNAi) or gene silencing is a natural defence response of plants to invading viruses. Here, we applied this approach against pepino mosaic virus (PepMV) isolates in their natural host, tomato. PepMV isolates differ in their genetic sequences, the severity of the disease they induce, and their worldwide distribution. PepMV causes heavy crop losses, mainly due to impaired tomato fruit quality. Resistant varieties are not yet available, despite many years of resistance breeding efforts within the tomato seed industry. To generate broad resistance to PepMV strains, conserved sequences from three different strains of PepMV (US1, LP, and CH2) were synthesized as a single insert and cloned in a hairpin configuration into a binary vector, which was used to transform tomato plants. Transgenic tomato lines that expressed a high level of transgene-siRNA exhibited immunity to PepMV strains, including a new Israeli isolate. This immunity was maintained even after graft inoculation, in which a transgenic scion was grafted onto nontransgenic infected rootstocks. However, an immune transgenic rootstock was unable to induce resistance in a nontransformed scion. These results provide the first example of engineered immunity to diverse PepMV strains in transgenic tomato based on gene silencing.     

防治烟草花叶病的药剂筛选

对目前市场上常见的6种病毒抑制剂进行防治烟草花叶病的田间试验和人工示范，结果表明：2％菌克毒克250倍液防治效果最好。从花叶病发病初期开始每7d喷药1次，共喷3次，第1次喷药后7d调查，防效为76．2％，第3次喷药后7d调查，防效达71．6％，大田示范平均防效为70．1％。其次为病毒必克500倍液和毒消600倍液。3种药剂的防效均显著高于其它几种供试药剂，值得推广应用。为避免抗性的产生，建议在生产中交替使用。     

Improved Selection with Newly Identified RAPD Markers Linked to Resistance Gene to Four Pathotypes of Colletotrichum lindemuthianum in Common Bean

ABSTRACT Three F(2) populations derived from crosses between the resistant cultivar AB 136 and the susceptible cultivar Michelite (MiA), and one F(2) population derived from a cross between AB 136 and Mexico 222 (MeA), were used to identify markers linked to anthracnose resistance genes present in cultivar AB 136. Primer OPZ04 produced a DNA band (OPZ04(560)) linked in coupling phase to the resistance gene for pathotype 89 (8.5 +/- 0.025 cM) in one population derived from the cross MiA. In the same population, primer OPZ09 produced one band (OPZ09(950)) linked in repulsion phase (20.4 +/- 0.014 cM) to the same resistance gene. The simultaneous use of markers in coupling and in repulsion phases allowed the identification of the three genotypic classes. In the other two populations from cross MiA, OPZ04(560) was linked in coupling phase to resistance genes for pathotypes 73 (2.9 +/- 0.012 cM) and 81 (2.8 +/- 0.017 cM). In population MeA, OPZ04(560) was linked in coupling phase (7.5 +/- 0.033 cM) to resistance to pathotype 64. These data suggest that a single gene or complex locus of linked resistance genes present in cultivar AB 136 confers resistance to all four pathotypes of C. lindemuthianum.     

Identification of Random Amplified Polymorphic DNA Markers Linked to the Co-4 Resistance Gene to Colletotrichum lindemuthianum in Common Bean

ABSTRACT New cultivars of the common bean (Phaseolus vulgaris) with durable resistance to anthracnose can be developed by pyramiding major resistance genes using marker-assisted selection. To this end, it is necessary to identify sources of resistance and molecular markers tightly linked to the resistance genes. The objectives of this work were to study the inheritance of resistance to anthracnose in the cultivar TO (carrying the Co-4 gene), to identify random amplified polymorphic DNA (RAPD) markers linked to Co-4, and to introgress this gene in the cultivar Rudá. Populations F(1), F(2), F(2:3), BC(1)s, and BC(1)r from the cross Rudá x TO were inoculated with race 65 of Colletotrichum lindemuthianum, causal agent of bean anthracnose. The phenotypic ratios (resistant/susceptible) were 3:1 in the F(2) population, 1:1 in the BC(1)s, and 1:0 in the BC(1)r, confirming that resistance to anthracnose in the cultivar TO was monogenic and dominant. Six RAPD markers linked to the Co-4 gene were identified, four in the coupling phase: OPY20(830C) (0.0 centimorgan [cM]), OPC08(900C) (9.7 cM), OPI16(850C) (14.3 cM), and OPJ01(1,380C) (18.1 cM); and two in the repulsion phase: OPB03(1,800T) (3.7 cM) and OPA18(830T) (17.4 cM). OPY20(830C) and OPB03(1,800T), used in association as a codominant pair, allowed the identification of the three genotypic classes with a high degree of confidence. Marker OPY20(830C), which is tightly linked to Co-4, is being used to assist in breeding for resistance to anthracnose.