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Type: Journal article
Title: Chromosomes carrying meiotic avoidance loci in three apomictic eudicot Hieracium subgenus Pilosella species share structural features with two monocot apomicts
Author: Okada, T.
Ito, K.
Johnson, S.
Oelkers, K.
Suzuki, G.
Houben, A.
Mukai, Y.
Koltunow, A.
Citation: Plant Physiology, 2011; 157(3):1327-1341
Publisher: American Society of Plant Biologists
Issue Date: 2011
ISSN: 1532-2548
Statement of
Takashi Okada, Kanae Ito, Susan D. Johnson, Karsten Oelkers, Go Suzuki, Andreas Houben, Yasuhiko Mukai and Anna M. Koltunow
Abstract: The LOSS OF APOMEIOSIS (LOA) locus is one of two dominant loci known to control apomixis in the eudicot Hieracium praealtum. LOA stimulates the differentiation of somatic aposporous initial cells after the initiation of meiosis in ovules. Aposporous initial cells undergo nuclear proliferation close to sexual megaspores, forming unreduced aposporous embryosacs, and the sexual program ceases. LOA-linked genetic markers were used to isolate 1.2 Mb of LOA-associated DNAs from H.praealtum. Physical mapping defined the genomic region essential for LOA function between two markers, flanking 400 kb of identified sequence and central unknown sequences. Cytogenetic and sequence analyses revealed that the LOA locus is located on a single chromosome near the tip of the long arm and surrounded by extensive, abundant complex repeat and transposon sequences. Chromosomal features and LOA-linked markers are conserved in aposporous Hieracium caespitosum and Hieracium piloselloides but absent in sexual Hieracium pilosella. Their absence in apomictic Hieracium aurantiacum suggests that meiotic avoidance may have evolved independently in aposporous subgenus Pilosella species. The structure of the hemizygous chromosomal region containing the LOA locus in the three Hieracium subgenus Pilosella species resembles that of the hemizygous apospory-specific genomic regions in monocot Pennisetum squamulatum and Cenchrus ciliaris. Analyses of partial DNA sequences at these loci show no obvious conservation, indicating that they are unlikely to share a common ancestral origin. This suggests convergent evolution of repeat-rich hemizygous chromosomal regions containing apospory loci in these monocot and eudicot species, which may be required for the function and maintenance of the trait.
Keywords: Chromosomes, Plant
DNA, Plant
DNA, Ribosomal
DNA Transposable Elements
Genetic Markers
Contig Mapping
Chromosome Segregation
Base Sequence
Repetitive Sequences, Nucleic Acid
Genome, Plant
Models, Genetic
Genetic Loci
Rights: Copyright © 2011 American Society of Plant Biologists. All rights reserved.
DOI: 10.1104/pp.111.181164
Appears in Collections:Agriculture, Food and Wine publications
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