A High-Resolution Linkage Map of the Citrus Tristeza Virus Resistance Gene Region in Poncirus trifoliata (L.) Raf.

Abstract Resistance to citrus tristeza virus (CTV) was evaluated in 554 progeny of 10 populations derived from Poncirus trifoliata. A dominant gene (Ctv) controlled CTV resistance in P. trifoliata. Twenty-one dominant PCR-based DNA markers were identified as linked to Ctv by bulked segregant analysis. Of the 11 closest markers to Ctv, only 2 segregated in all populations. Ten of these markers were cloned and sequenced, and codominant RFLP markers were developed. Seven RFLP markers were then evaluated in 10 populations. Marker orders were consistent in all linkage maps based on data of single populations or on combined data of populations with similar segregation patterns. In a consensus map, the six closest marker loci spanned 5.3 cM of the Ctv region. Z16 cosegregated with Ctv. C19 and AD08 flanked Ctv at distances of 0.5 and 0.8 cM, respectively. These 3 markers were present as single copies in the Poncirus genome, and could be used directly for bacterial artificial chromosome library screening to initiate a walk toward Ctv. BLAST searches of the GenBank database revealed high sequence similarities between 2 markers and known plant disease resistance genes, indicating that a resistance gene cluster exists in the Ctv region in P. trifoliata.

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Development and characterization of SCAR markers linked to the citrus tristeza virus resistance gene from Poncirus trifoliata

Genome ◽

10.1139/g97-792 ◽

1997 ◽

Vol 40 (5) ◽

pp. 697-704 ◽

Cited By ~ 45

Author(s):

Zhanao Deng ◽

Shunyuan Xiao ◽

Shu Huang ◽

Frederick G. Gmitter Jr.

Keyword(s):

Resistance Gene ◽

Virus Resistance ◽

Citrus Tristeza Virus ◽

Bulked Segregant Analysis ◽

Dominant Gene ◽

Poncirus Trifoliata ◽

Scar Markers ◽

Citrus Tristeza Virus Resistance ◽

Tristeza Virus ◽

Citrus Tristeza

Twelve new dominant randomly amplified polymorphic DNA (RAPD) fragments associated with a single dominant gene for resistance to citrus tristeza virus (CTV) were identified using bulked segregant analysis of an intergeneric backcross family. These and eight previously reported RAPDs were mapped in the resistance gene (Ctv) region; the resulting localized linkage map spans about 32 cM, with nine close flanking markers within 2.5 cM of Ctv. Seven of 20 RAPD fragments linked with the resistance gene were cloned and sequenced, and their sequences were used to design longer primers to develop sequence characterized amplified region (SCAR) markers that can be utilized reliably in marker-assisted selection, high-resolution mapping, and map-based cloning of the resistance gene. All seven cloned RAPDs were converted successfully into SCARs by redesigning primers, optimizing PCR parameters (especially the annealing temperature), or digesting amplification products with restriction enzymes. Four of the seven remained dominant markers, displaying presence–absence polymorphism patterns; the other three detected restriction site changes or length variations and thus were transformed into codominant markers. Two genomic regions rich in variability were also detected by two codominant SCAR markers.Key words: RAPD, gene mapping, citrus tristeza virus resistance.

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Construction of a 1.2-Mb contig including the citrus tristeza virus resistance gene locus using a bacterial artificial chromosome library of Poncirus trifoliata (L.) Raf.

Genome ◽

10.1139/g01-021 ◽

2001 ◽

Vol 44 (3) ◽

pp. 382-393 ◽

Cited By ~ 10

Author(s):

Zhong-Nan Yang ◽

Xin-Rong Ye ◽

Sandong Choi ◽

Joe Molina ◽

Francis Moonan ◽

...

Keyword(s):

Resistance Gene ◽

Virus Resistance ◽

Citrus Tristeza Virus ◽

Bac Library ◽

Artificial Chromosome ◽

Poncirus Trifoliata ◽

Citrus Tristeza Virus Resistance ◽

Tristeza Virus ◽

Virus Resistance Gene ◽

Citrus Tristeza

The citrus tristeza virus resistance gene (Ctv) is a single dominant gene in Poncirus trifoliata, a sexually compatible relative of citrus. To clone this gene, a bacterial artificial chromosome (BAC) library has been constructed from an individual plant that was homozygous for Ctv. This library contains 45 696 clones with an average insert size of 80 kb, corresponding to 9.6 genome equivalents. Screening of the BAC library with five chloroplast DNA probes indicated that 0.58% of the BAC clones contained chloroplast-derived inserts. The chromosome walk across the Ctv locus was initiated using three closely linked genetic markers: C19, AD8, and Z16. The walk has been completed and a contig of ca. 1.2 Mb was constructed. Based on new data, the genetic map in the Ctv region was revised, with Ctv being located between AD8-Z16 and C19 at distances of 1.2 and 0.6 cM, respectively. Utilizing DNA fragments isolated from the contig as RFLP markers, the Ctv locus was further mapped to a region of ca. 300 kb. This contig contains several putative disease-resistance genes similar to the rice Xa21 gene, the tomato Cf-2 gene, and the Arabidopsis thaliana RPS2 gene. This library will therefore allow cloning of Ctv and other putative disease-resistance genes.Key words: Poncirus, citrus tristeza virus, chromosome walk, resistance gene.

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MOLECULAR MARKERS LINKED TO CITRUS TRISTEZA VIRUS (CTV) RESISTANCE GENE IN CULTIVARS AND HYBRIDS OF PONCIRUS TRIFOLIATA

Acta Horticulturae ◽

10.17660/actahortic.2000.535.28 ◽

2000 ◽

pp. 231-236

Author(s):

M. Cristofani ◽

M.A. Machado

Keyword(s):

Molecular Markers ◽

Resistance Gene ◽

Citrus Tristeza Virus ◽

Poncirus Trifoliata ◽

Tristeza Virus ◽

Ctv Resistance ◽

Citrus Tristeza

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A Novel Gene Conferring Citrus Tristeza Virus Resistance in Citrus maxima (Burm.) Merrill

HortScience ◽

10.21273/hortsci.34.2.334 ◽

1999 ◽

Vol 34 (2) ◽

pp. 334-335 ◽

Cited By ~ 15

Author(s):

D.Q. Fang ◽

M.L. Roose

Keyword(s):

Virus Resistance ◽

Citrus Tristeza Virus ◽

Dominant Gene ◽

Poncirus Trifoliata ◽

Trifoliate Orange ◽

Citrus Maxima ◽

Progeny Analysis ◽

Citrus Tristeza Virus Resistance ◽

Tristeza Virus ◽

Citrus Tristeza

`Chandler' pummelo [Citrus maxima (Burm.) Merrill] was found to be citrus tristeza virus (CTV)–resistant. The inheritance of this resistance in 84 progeny of two crosses derived from `Chandler' pummelo and trifoliate orange [Poncirus trifoliata (L.) Raf.] was controlled by a single dominant gene designated Ctv2. Progeny analysis of four molecular markers closely linked to the Ctv gene, which confers resistance to CTV in trifoliate orange, demonstrated that Ctv2 was an independently assorting gene from Ctv.

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