APOMICTIC SEED PRODUCTION IN POA PRATENSIS L.: TOWARDS THE UNDERSTANDING OF ITS GENETIC CONTROL

G. Barcaccia¹ and M. Falcinelli²

¹Dipartimento di Agronomia Ambientale e Produzioni Vegetali, University of Padova, Agripolis, Via Romea 16, 35020 Legnaro, Padova, Italy;

²Istituto di Miglioramento Genetico Vegetale, University of Perugia, Borgo XX Giugno 74, 06100 Perugia, Italy.

Apomixis, as it exists in Kentucky bluegrass (Poa pratensis L.), is a nearly ideal way of maintaining superior hybrids and complex traits. It combines the genetic advantages of vegetative propagation (maintenance of the genotype) with the agronomic advantages of sexual reproduction (use of the seed).  Lack of knowledge on its inheritance at present hinders attempts to manipulate and transfer the apomictic trait beyond natural sexual barriers. Independent cito-embryological and molecular progeny tests have indicated that only a single dominant allele is required for the genetic transmission of parthenogenesis.  Moreover, histological investigations have suggested that the two essential components leading to apomixis are strictly associated: sexual, non-parthenogenetic plants completely lack aposporic activity in ovules while apomictic plants are highly aposporic and parthenogenetic.  The finding of highly significant linkages between molecular markers and the mode of reproduction further agrees with the hypothesis of one single genetic factor responsible for the whole developmental process of apomictic seed setting in this species.  Although the question remains open, in P. pratensis apomixis seems to be a monogenetically inherited system or the result of a few tightly clustered genes rather than the combination of two processes, apospory and parthenogenesis, determined by independent genetic factors.

Keywords: Poa pratensis; apospory; parthenogenesis; apomixis.