Am. J. Bot. SilverBiology ad
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Liu, Z.-L.
Right arrow Articles by Wang, X.-R.
Right arrow Search for Related Content
PubMed
Right arrow Articles by Liu, Z.-L.
Right arrow Articles by Wang, X.-R.
Agricola
Right arrow Articles by Liu, Z.-L.
Right arrow Articles by Wang, X.-R.
(American Journal of Botany. 2003;90:17-24.)
© 2003 Botanical Society of America, Inc.

Genetics and Molecular Biology

Intragenomic and interspecific 5S rDNA sequence variation in five Asian pines1

Zhan-Lin Liu2, Daming Zhang2, Xiao-Quan Wang2, Xiao-Fei Ma2 and Xiao-Ru Wang2,3,4

2Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; 3National Institute for Working Life, SE-907 13 Umeå, Sweden

Patterns of intragenomic and interspecific variation of 5S rDNA in Pinus (Pinaceae) were studied by cloning and sequencing multiple 5S rDNA repeats from individual trees. Five pines, from both subgenera, Pinus and Strobus, were selected. The 5S rDNA repeat in pines has a conserved 120-base pair (bp) transcribed region and an intergenic spacer region of variable length (382–608 bp). The evolutionary rate in the spacer region is three- to sevenfold higher than in the genic region. We found substantial sequence divergence between the two subgenera. Intragenomic sequence heterogeneity was high for all species, and more than 86% of the clones within each individual were unique. The 5S gene tree revealed that different 5S repeats within individuals are polyphyletic, indicating that their ancestral divergence preceded the speciation events. The degrees of interspecific and intragenomic divergence among diploxylon pines are similar. The observed sequence patterns suggest that concerted evolution has been acting after the diversification of the two subgenera but very weak after the speciation of the four diploxylon pines. Sequence patterns in P. densata are consistent with hybrid origin. It had higher intragenomic diversity and maintained polymorphic copies of the parental types in addition to new and recombinant types unique to the hybrid.

Key Words: concerted evolution • Pinaceae • Pinus • 5S rDNA • sequence heterogeneity






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2003 by the Botanical Society of America, Inc.