Читать книгу Principles of Plant Genetics and Breeding - George Acquaah - Страница 295

Recent and past research strongly suggests that there is little homeology between the genomes of Tripsacum and maize. Maguire (1962), utilizing a set of recessive phenotypic maize markers, suggested that only maize chromosomes 2, 5, 8, and 9 have a potential for pairing and recombination and for gene introgression with Tripsacum. Additional research has confirmed conservation of loci specific to pistil development between maize and Tripsacum genomes (Kindiger et al. 1995; Li et al. 1997). Maguire (1957, 1960) successfully generated and identified a naturally occurring recombination event between an unknown Tripsacum chromosome and the short arm of maize chromosome 2. Studies using B‐A translocation deletion lines suggested that the Mz9S region could pair and recombine with Tripsacum chromosome 5. Genomic in situ hybridization (GISH) studies have also strongly suggested that only three regions of maize chromosomes have homeology with the Tripsacum genome: the sub‐terminal regions of Mz2S, Mz6L, and Mz8L (Poggio et al. 1999). These regions correspond well with groups of conserved restriction fragment length polymorphism (RFLP) markers identified between maize and Tripsacum genomes (Blakey et al. 1994; Leblanc et al. 1995). As a consequence, few sites are available for Tripsacum introgression into the maize genome and, to date, only two instances are known where verifiable recombination/translocation events have occurred (Maguire 1962; Kindiger et al. 1996b).