Publication Date

1989

Description

In Medicago genus, the importance of gametes with unreduced chromosome number (2n gametes) has been stressed both in the evolution (Stanford et al., 1972) and breeding (Bingham, 1968) of cultivated alfalfa, wich is a cross-fertilizing natural polysomic polyploid (Medicago sativa L., 2n = 4x = 32). In this species heterozygosity can be maximized but not fixed by the usual methods of cultivar development (Dubier and Bingham, 1975). As an alternative to normal sexual repro­duction, hybridization of 2n gametes from diploid hybrids can transmit, through bilateral sexual polyploidization, a large part of the heterozygosity of the diploid parents to the tetraploid offsprings (McCoy and Rowe, 1986). The main objective of the present research was to identify genotypes able to produce high frequencies of male and female 2n gametes in natural diploid populations belonging to the Medicago sativa-coerulea-falcata complex.

Share

COinS
 

2N Gamete Producer in Diploid Species of Genus Medicago

In Medicago genus, the importance of gametes with unreduced chromosome number (2n gametes) has been stressed both in the evolution (Stanford et al., 1972) and breeding (Bingham, 1968) of cultivated alfalfa, wich is a cross-fertilizing natural polysomic polyploid (Medicago sativa L., 2n = 4x = 32). In this species heterozygosity can be maximized but not fixed by the usual methods of cultivar development (Dubier and Bingham, 1975). As an alternative to normal sexual repro­duction, hybridization of 2n gametes from diploid hybrids can transmit, through bilateral sexual polyploidization, a large part of the heterozygosity of the diploid parents to the tetraploid offsprings (McCoy and Rowe, 1986). The main objective of the present research was to identify genotypes able to produce high frequencies of male and female 2n gametes in natural diploid populations belonging to the Medicago sativa-coerulea-falcata complex.