7 Genome structure and mapping

Quirós, Carlos F.

doi:10.1016/s0168-7972(99)80008-5

Cited by 22 publications

(11 citation statements)

References 95 publications

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“…The first DNA-based marker technique used for the construction of linkage maps was based on the use of restriction fragment length polymorphism (RFLP). RFLP-based linkage maps have been developed in some of the important Brassica species (Quiros 1999), including B. juncea (Cheung et al 1997;Axelsson et al 2000). A major advantage of RFLP markers is that these are predominantly co-dominant.…”

Section: Introductionmentioning

confidence: 99%

A high-density linkage map in Brassica juncea (Indian mustard) using AFLP and RFLP markers

et al. 2003

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A high-density genetic linkage map of Brassica juncea (2n = 36) was constructed with 996 AFLP (amplified fragment length polymorphism) and 33 RFLP (restriction fragment length polymorphism) markers using a F1-derived doubled-haploid (DH) population of 123 individuals. This mapping population was developed by crossing a well-adapted, extensively grown Indian variety Varuna and a canola quality line Heera. The two lines are highly divergent and contain a number of contrasting qualitative and quantitative traits of high agronomic value. AFLPs were generated by the use of restriction enzymes EcoRI or PstI in combination with either MseI or TaqI. Using 91 primer pairs, a total of 1,576 parental polymorphic bands were detected of which 996 were used for mapping. In addition, 33 RFLP markers, developed from genomic clones of B. napus, were added to the map. The segregation of each marker and linkage analysis was performed using the program JoinMap version 2.0. The 1,029 mapped-markers were aligned in 18 linkage groups, which is the haploid chromosome number of the species, at LOD values ranging from 5 to 8. The total map length was 1,629 cM with an average marker interval of 3.5 cM. AFLP markers generated by EcoRI were more clustered, whereas PstI markers showed more extensive distribution. A set of 26 primer pairs (9 EcoRI/ MseI, 6 EcoRI/ TaqI, 6 PstI/ MseI and 5 PstI/ TaqI) generating 385 markers were identified for AFLP-based whole-genome selection as these markers covered 96% of the genome mapped with the 91 primer pairs. The map developed in the present study could be used for dissection and the transfer of agronomically important traits and favourable QTLs from ill-adapted exotic germplasm to cultivated Indian varieties.

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Section: Introductionmentioning

confidence: 99%

A high-density linkage map in Brassica juncea (Indian mustard) using AFLP and RFLP markers

et al. 2003

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“…The genetics of oilseed rape (Brassica napus L. 2n=38, genome AACC), now one of the most important oilseed crops worldwide, are complex because it is an amphidiploid composed of two related genomes which themselves are thought to represent ancestral hexaploids ; see also Truco et al 1996;Quiros 1999). B. napus originated from a spontaneous hybridisation of Brassica rapa L. (syn.…”

Section: Introductionmentioning

confidence: 99%

Identifying the chromosomes of the A- and C-genome diploid Brassica species B. rapa (syn. campestris) and B. oleracea in their amphidiploid B. napus

Snowdon¹,

Friedrich²,

Friedt³

et al. 2002

Theor Appl Genet

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Oilseed rape ( Brassica napus L.) is an amphidiploid species that originated from a spontaneous hybridisation of Brassica rapa L. (syn. campestris) and Brassica oleracea L., and contains the complete diploid chromosome sets of both parental genomes. The metaphase chromosomes of the highly homoeologous A genome of B. rapa and the C genome of B. oleracea cannot be reliably distinguished in B. napus because of their morphological similarity. Fluorescence in situ hybridisation (FISH) with 5S and 25S ribosomal DNA probes to prometaphase chromosomes, in combination with DAPI staining, allows more dependable identification of Brassica chromosomes. By comparing rDNA hybridisation and DAPI staining patterns from B. rapa and B. oleracea prometaphase chromosomes with those from B. napus, we were able to identify the putative homologues of B. napus chromosomes in the diploid chromosome sets of B. rapa and B. oleracea, respectively. In some cases, differences were observed between the rDNA hybridisation patterns of chromosomes in the diploid species and their putative homologue in B. napus, indicating locus losses or alterations in rDNA copy number. The ability to reliably identify A and C genome chromosomes in B. napus is discussed with respect to evolutionary and breeding aspects.

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“…Moreover, at least two bivalents each are expected due to intra-genome duplications in A or B genomes alone (Röbbelen 1966;Truco et al 1996). Autopairs are also likely in the E cd genome, as Brassicaceae members are considered to be paleoploids with a basic chromosome number of x=5 or 6 (Quiros 1999). Despite the inherent duplications, allosyndetic pairing between the A/B and E cd genomes was indicated by the frequent occurrence of anaphase bridges, which are the manifestation of genetic exchange in the region of homology between structurally differentiated genomes.…”

Section: Discussionmentioning

confidence: 99%

“…The demonstration of partial genome homologies between Erucastrum and Brassica was confirmative of the species classification based on conventional taxonomy where both Erucastrum and Brassica have been grouped together. That both the A and B genomes were partially homoeologous with the E cd genome appeared interesting due to the established evolutionary diversion between the A and B genomes (Quiros 1999). Successful synthesis of two intergeneric hybrids between E. cardaminoides B. rapa and E. cardaminoides B. nigra has now opened up the possibility of genetic enrichment of crop Brassica species through gene introgression from this genera.…”

Section: Discussionmentioning

confidence: 99%

Intergeneric hybridization between Erucastrum cardaminoides and two diploid crop Brassica species

et al. 2004

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Two intergeneric hybrids involving wild species Erucastrum cardaminoides (2 n=18, E(cd) E(cd)) and two crop brassica species, Brassica rapa (2 n=20, AA) and B. nigra (2 n=16, BB), were synthesized through in vitro sequential ovary culture. Morphological, molecular and cytological studies were conducted to establish their hybridity. Both hybrids, though morphologically distinct, were intermediate phenotypically between their respective parents. Cytological analysis of the E. cardaminoides x B. rapa hybrid (2 n=19), revealed the occurrence of 17 I+1 II at diakinesis/metaphase in the majority (28%) of the pollen mother cells (PMCs), whereas in E. cardaminoides x B. nigra hybrid (2 n=17), 13 I+2 II was the predominant (32%) meiotic configuration. A maximum of 5 II was recorded in both hybrids, indicating homoeologous pairing in the respective combined genomes. Chromosome doubling by colchicine application gave rise to two new amphiploids (AA E(cd)E(cd) and BB E(cd)E(cd)) having normal chromosome pairing and pollen fertility. The occasional occurrence of one quadrivalent in the amphiploids confirmed partial homoeology between the E(c) and A/B genomes. The E. cardaminoides x B. nigra hybrid and amphiploid appeared to be tolerant to alternaria blight under field conditions.

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7 Genome structure and mapping

Cited by 22 publications

References 95 publications

A high-density linkage map in Brassica juncea (Indian mustard) using AFLP and RFLP markers

A high-density linkage map in Brassica juncea (Indian mustard) using AFLP and RFLP markers

Identifying the chromosomes of the A- and C-genome diploid Brassica species B. rapa (syn. campestris) and B. oleracea in their amphidiploid B. napus

Intergeneric hybridization between Erucastrum cardaminoides and two diploid crop Brassica species

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