An Unusual Ribosomal DNA Sequence from Gossypium gossypioides Reveals Ancient, Cryptic, Intergenomic Introgression

Wendel, Jonathan F.; Schnabel, Andrew; Seelanan, Tosak

doi:10.1006/mpev.1995.1027

Cited by 234 publications

(238 citation statements)

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“…We investigated whether the number and location of the rDNA loci is the sum of that found in the putative parents, and whether concerted evolution has altered or homogenised units as has occurred in N. tabacum. The results are also interpreted in the light of other rDNA unit arrays previously described in allopolyploids in Triticum (Flavell, 1990), Brassica (Chen and Pikaard, 1997) and Gossypium (Wendel et al, 1995a).…”

Section: Introductionmentioning

confidence: 53%

Ribosomal DNA evolution and gene conversion in Nicotiana rustica

et al. 2003

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Genomic in situ hybridisation was used to confirm that Nicotiana rustica (2n ¼ 4x ¼ 48) is an allotetraploid between N. paniculata (2n ¼ 2x ¼ 24, maternal P-genome donor) and N. undulata (2n ¼ 2x ¼ 24, paternal U-genome donor), their progenitors or species closely related to them. Fluorescent in situ hybridisation showed that N. paniculata has one 5S and two 18-5.8-26S rDNA loci whereas N. undulata has an additional 18-5.8-26S rDNA locus. N. rustica has the sum of the loci found in these putative parents. The sizes of the 18-5.8-26S rDNA loci indicate that the number of rDNA units on the U-genome chromosomes has amplified; perhaps this is associated with a concomitant reduction in the number of units on P-genome chromosomes. Restriction fragment length polymorphism analysis of the intergenic spacer (IGS) of the 18-5.8-26S rDNA units in N. rustica and the two progenitor diploids revealed that about 80% of IGS sequences in N. rustica are of an N. undulata type and 20% of N. paniculata type. These data indicate that interlocus sequence homogenisation has caused the replacement of many N. paniculata-type IGSs in N. rustica with an N. undulata-type of sequence. It is probable that subsequent to this replacement there has been sequence divergence at the 5 0 end of the IGS. As in tobacco, an allotetraploid between N. sylvestris and N. tomentosiformis, the direction of the IGS interlocus conversion is towards the paternal genome donor.

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Section: Introductionmentioning

confidence: 53%

Ribosomal DNA evolution and gene conversion in Nicotiana rustica

et al. 2003

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“…genetic revolution, in which physiologically interacting genes re-adapt to one another in new genetic alignments'' (31-33). Several recently described mechanisms may provide new mutations (and quantitative genetic variation) immediately after polyploid formation (7,(34)(35)(36), whereas the ''bufferring'' effect of the alternative genome underpins the fitness of the organism. ''Directional genomic change'' of the paternally donated D subgenome (6) away from its progenitor, as suggested for Brassica (35), would be consistent with the phenotypic variation that we observe in cotton.…”

Section: Discussionmentioning

confidence: 99%

Polyploid formation created unique avenues for response to selection in Gossypium (cotton)

Jiang

Wright

El-Zik

et al. 1998

Proc. Natl. Acad. Sci. U.S.A.

318

249

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A detailed restriction fragment length polymorphism map was used to determine the chromosomal locations and subgenomic distributions of quantitative trait loci (QTLs) segregating in a cross between cultivars of allotetraploid (AADD) Gossypium hirsutum (''Upland'' cotton) and Gossypium barbadense (''Sea Island,'' ''Pima,'' or ''Egyptian'' cotton) that differ markedly in the quality and quantity of seed epidermal fibers. Most QTLs inf luencing fiber quality and yield are located on the ''D'' subgenome, derived from an ancestor that does not produce spinnable fibers. D subgenome QTLs may partly account for the fact that domestication and breeding of tetraploid cottons has resulted in fiber yield and quality levels superior to those achieved by parallel improvement of ''A'' genome diploid cottons. The merger of two genomes with different evolutionary histories in a common nucleus appears to offer unique avenues for phenotypic response to selection. This may partly compensate for reduction in quantitative variation associated with polyploid formation and be one basis for the prominence of polyploids among extant angiosperms. These findings impel molecular dissection of the roles of divergent subgenomes in quantitative inheritance in many other polyploids and further exploration of both ''synthetic'' polyploids and exotic diploid genotypes for agriculturally useful variation.

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“…Before fortifying its reproductive barriers, the nascent polyploid may have occasionally outcrossed to nearby D-genome diploids, increasing the likelihood of illegitimate recombination. Outcrossing may also have contributed to the origin of Gossypium gossypioides, sister to G. raimondii and the only D-genome cotton containing many otherwise A-genome-specific repetitive DNAs [27][28][29] . D t -biased allele conversion may have contributed to slightly greater protein-coding nucleotide diversity in the A t compared with the D t -genome (Supplementary Table 5.7).…”

Section: Letter Research Distribution (Supplementarymentioning

confidence: 99%