Sectional delineation of sexual Tripsacum dactyloides-T. maizar allotriploids
2000
Li, Y.G. | Dewald, C.L. | Sokolov, V.A.
In recent studies it was determined that certain allotriploids produced from crosses of sexual diploid Tripsacum dactyloides (2 n = 2 x = 36), section Tripsacum and apomictic tetraploid T. maizar (2 n = 4 x = 72), section Fasciculata reproduce sexually. Backcrossing progenies can be clearly classified to either sect. Tripsacum or sect. Fasciculata due to their distinctively different inflorescence phenotype. More importantly, the sectional delineation of the progeny shifted in the direction of the pollinator through genome substitution, which is not to be expected following just one generation of backcrossing in a normal breeding program. Our main objective was to investigate whether there were potential genetic differences between the genomes from sect. Tripsacum and sect. Fasciculata at the molecular level that correlate with such morphological shifts in these unusual sexual allotriploids. Cluster analysis based on randomly amplified polymorphic DNA (RAPD) profiles of these sexual allotriploids clearly indicated that substantial differences among many loci do exist between T. dactyloides and T. maizar . These results support the taxonomic classification of Tripsacum species into section Tripsacum and section Fasciculata.
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