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Diversity and dynamics of plant genome size: An example of polysomaty from a cytogenetic study of Tahitian vanilla (Vanilla ×tahitensis, Orchidaceae)
Author(s) -
LepersAndrzejewski Sandra,
SiljakYakovlev Sonja,
Brown Spencer C.,
Wong Maurice,
Dron Michel
Publication year - 2011
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.1000415
Subject(s) - biology , ploidy , aneuploidy , endoreduplication , botany , chromosome , sexual reproduction , meristem , hybrid , orchidaceae , genetics , gene , shoot
• Premise of the study: Abnormal mitotic behavior with somatic aneuploidy and partial endoreplication were previously reported for the first time in the plant kingdom in Vanilla planifolia . Because vanilla plants are vegetatively propagated, such abnormalities have been transmitted. This study aimed to determine whether mitotic abnormalities also occur in Vanilla hybrid or are suppressed by sexual reproduction. • Methods: Twenty‐eight accessions of Vanilla × tahitensis , one V. planifolia , and hybrid V. planifolia × V . × tahitensis were analyzed by chromosome counts, cytometry, and fluorescent in situ hybridization of 18S–5.8S–26S rDNA. • Key results: In a single root meristem of V . × tahitensis , chromosome number varied from 22 to 31 in diploids (mean 2C = 5.23 pg), 31 to 41 in triploids (2C = 7.82 pg) and 43 to 60 in tetraploids (2C = 10.27 pg). Morphological diversity is apparently related to ploidy changes. Aneuploidy and partial (asymmetrical) endoreduplication were observed in root meristems of both V . × tahitensis and the hybrid V. planifolia × V . × tahitensis , but pollen grains had the euploid chromosome number ( n = 15 in diploids). • Conclusions: Genome irregularities may be transmitted not only during vegetative propagation but also by sexual reproduction in Vanilla . However, there must be a complex regulation of genome size and organization between the aneuploidy in somatic tissues and subsequently euploid gametic tissue. This is a novel example of polysomaty with developmentally regulated partial endoreplication.