Inheritance of parthenogenesis in Poa pratensis L.: auxin test and AFLP linkage analyses support monogenic control |
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Authors: | G Barcaccia A Mazzucato E Albertini J Zethof A Gerats M Pezzotti M Falcinelli |
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Institution: | (1) Istituto di Miglioramento Genetico Vegetale, Faculty of Agriculture, University of Perugia, Borgo XX Giugno 74, I-06100 Perugia, Italy Fax: +75 585 6224 E-mail: imgv@unipg.it, IT;(2) Dipartimento di Agrobiologia e Agrochimica, University of Viterbo, Via SC de Lellis 1, I-01100 Viterbo, Italy, IT;(3) Laboratorium voor Genetica, Department of Genetics, University of Gent, Ledeganckstraat 35, B-9000 Gent, Belgium, BE |
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Abstract: | Gametophytic apomixis in Kentucky bluegrass (Poa pratensis L.) involves the parthenogenetic development of unreduced eggs from aposporic embryo sacs. Attempts to transfer the apomictic
trait beyond natural sexual barriers require further elucidation of its inheritance. Controlled crosses were made between
sexual clones and apomictic genotypes, and the parthenogenetic capacity of (poly)diploid hybrids was ascertained by the auxin
test. A bulked segregant analysis with RAPD and AFLP markers was then used to identify a genetic linkage group related to
the apomictic mode of reproduction. This approach enabled us to detect both an AFLP marker located 6.6 cM from the gene that
putatively controls parthenogenesis and a 15.4-cM genomic window surrounding the target locus. A map of the P. pratensis chromosome region carrying the gene of interest was constructed using additional RAPD and AFLP markers that co-segregated
with the parthenogenesis locus. Highly significant linkage between parthenogenesis and a number of AFLP markers that also
appeared to belong to a tight linkage block strengthens the hypothesis of monogenic inheritance of this trait. If a single
gene is assumed, apomictic polyploid types of P. pratensis would be simplex for a dominant allele that confers parthenogenesis, and this genetic model would be further supported by
the bimodal distribution of the degree of parthenogenesis exhibited in the (poly)diploid progenies from sexual x apomictic
matings. The molecular tagging of apomixis in P. pratensis is an essential step towards marker-assisted breeding and map-based cloning strategies aimed at investigating and manipulating
its mode of reproduction.
Received: 13 January 1998 / Accepted: 19 January 1998 |
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Keywords: | Apomixis Auxin test analysis Bulked segregant analysis Gene mapping Kentucky bluegrass Parthenogenesis Molecular markers |
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