Proceedings of the XLV Italian Society of Agricultural Genetics - SIGA Annual Congress

Salsomaggiore Terme, Italy - 26/29 September, 2001

ISBN 88-900622-1-5

Poster Abstract

TWO DISTINCT GENETIC FACTORS SEEM TO CONTROL APOSPORY AND PARTHENOGENESIS IN POA PRATENSIS L.

ALBERTINI E.*, FERRANTI F., REALE L., ROMANO B., FALCINELLI M.

Dipartimento di Biologia Vegetale e Biotecnologie Agroambientali, Università degli Studi di Perugia, Borgo XX Giugno 74, 06121 Perugia.

* emidalb@tiscalinet.it; web.tiscalinet.it\emidioalbertini

apomixis, apospory, parthenogenesis, Poa pratensis, genetic control

Kentucky bluegrass (Poa pratensis L.), an attractive forage and turf grass, reproduces mainly through pseudogamous facultative aposporous apomixis. Apospous apomixis is functionally composed of two processes: apospory and parthenogenesis. Apospory is the development of embryo sacs starting from cells that differentiate from the nucellus. In P. pratensis these aposporous embryo sacs develop through parthenogenesis in viable apomictic seeds if the unreduced polar nuclei fuses with a sperm cell from the male gametophyte (pseudogamy). This mode of reproduction is highly prized by breeders, as propagating the maternal genotype, allows development of varieties that breed true regardless of heterozygosity. Proper manipulation of apomixis requires knowledge of at least three different aspects of the trait: I) unreduced aposporic megagametophyte formation; II) parthenogenesis; III) endosperm development. Despite the potential that apomixis has for agriculture, there is but little information regarding the genetic control of its functional components. We carried out a cytohistological investigation on an F₁ segregating population of Poa pratensis obtained from a cross between a sexual and an apomictic parent. About half of the F₁ progeny plants were parthenogenic, as adjudicated by an auxin test. In addition, while apospory was scored in all parthenogenic individuals, two non-parthenogenic genotypes showed aposporous initials. These findings suggest that I) parthenogenesis is contingent on apospory but not vice-versa; II) the traits are controlled by distinct genetic factors. These results demonstrate that two distinct genetic factors control apospory and parthenogenesis in P. pratensis and that apospory and parthenogenesis may be developmentally uncoupled.