PMID- 19589857
OWN - NLM
STAT- MEDLINE
DCOM- 20091020
LR  - 20211020
IS  - 1095-8290 (Electronic)
IS  - 0305-7364 (Print)
IS  - 0305-7364 (Linking)
VI  - 104
IP  - 4
DP  - 2009 Sep
TI  - A bicontinental origin of polyploid Australian/New Zealand Lepidium species 
      (Brassicaceae)? Evidence from genomic in situ hybridization.
PG  - 681-8
LID - 10.1093/aob/mcp161 [doi]
AB  - BACKGROUND AND AIMS: Incongruence between chloroplast and nuclear DNA 
      phylogenies, and single additive nucleotide positions in internal transcribed 
      spacer (ITS) sequences of polyploid Australian/New Zealand (NZ) Lepidium species 
      have been used to suggest a bicontinental hybrid origin. This pattern was 
      explained by two trans-oceanic dispersals of Lepidium species from California and 
      Africa and subsequent hybridization followed by homogenization of the ribosomal 
      DNA sequence either to the Californian (C-clade) or to the African ITS-type 
      (A-clade) in two different ITS-lineages of Australian/NZ Lepidium polyploids. 
      METHODS: Genomic in situ hybridization (GISH) was used to unravel the genomic 
      origin of polyploid Australian/NZ Lepidium species. Fluorescence in situ 
      hybridization (FISH) with ribosomal DNA (rDNA) probes was applied to test the 
      purported ITS evolution, and to facilitate chromosome counting in high-numbered 
      polyploids. KEY RESULTS: In Australian/NZ A-clade Lepidium polyploids, GISH 
      identified African and Australian/NZ C-clade species as putative ancestral 
      genomes. Neither the African nor the Californian genome were detected in 
      Australian/NZ C-clade species and the Californian genome was not detected in 
      Australian/NZ A-clade species. Five of the eight polyploid species (from 7x to 
      11x) displayed a diploid-like set of rDNA loci. Even the undecaploid species 
      Lepidium muelleriferdinandi (2n = 11x = 88) showed only one pair of each rDNA 
      repeat. In A-clade allopolyploids, in situ rDNA localization combined with GISH 
      corroborated the presence of the African ITS-type. CONCLUSIONS: The nuclear 
      genomes of African and Australian/NZ C-clade species were detected by GISH in 
      allopolyploid Australian/NZ Lepidium species of the A-clade, supporting their 
      hybrid origin. The presumed hybrid origin of Australian/NZ C-clade taxa could not 
      be confirmed. Hence, it is assumed that Californian ancestral taxa experienced 
      rapid radiation in Australia/NZ into extant C-clade polyploid taxa followed by 
      hybridization with African species. As a result, A-clade allopolyploid Lepidium 
      species share the Californian chloroplast type and the African ITS-type with the 
      C-clade Australian/NZ polyploid and African diploid species, respectively.
FAU - Dierschke, Tom
AU  - Dierschke T
AD  - Universitat Osnabruck, Abteilung Botanik, Barbarastrasse 11, 49076 Osnabruck, 
      Germany. Tomiworld@gmx.de
FAU - Mandakova, Terezie
AU  - Mandakova T
FAU - Lysak, Martin A
AU  - Lysak MA
FAU - Mummenhoff, Klaus
AU  - Mummenhoff K
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20090709
PL  - England
TA  - Ann Bot
JT  - Annals of botany
JID - 0372347
RN  - 0 (DNA, Ribosomal Spacer)
RN  - 0 (Indoles)
RN  - 47165-04-8 (DAPI)
SB  - IM
MH  - Australia
MH  - Biological Evolution
MH  - Chromosomes, Plant/genetics
MH  - DNA, Ribosomal Spacer/genetics
MH  - Flowers/cytology/genetics
MH  - Genome, Plant/*genetics
MH  - Geography
MH  - *In Situ Hybridization
MH  - Indoles
MH  - Lepidium/*genetics
MH  - Mitosis
MH  - New Zealand
MH  - *Polyploidy
PMC - PMC2729636
EDAT- 2009/07/11 09:00
MHDA- 2009/10/21 06:00
PMCR- 2010/09/01
CRDT- 2009/07/11 09:00
PHST- 2009/07/11 09:00 [entrez]
PHST- 2009/07/11 09:00 [pubmed]
PHST- 2009/10/21 06:00 [medline]
PHST- 2010/09/01 00:00 [pmc-release]
AID - mcp161 [pii]
AID - 10.1093/aob/mcp161 [doi]
PST - ppublish
SO  - Ann Bot. 2009 Sep;104(4):681-8. doi: 10.1093/aob/mcp161. Epub 2009 Jul 9.