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Research was conducted to characterize the reproductive behavior of the highly sterile Tripsacum andersonii Gray and its viable progeny through breeding, cytological, and molecular studies. Four progeny were obtained from open-pollinated seeds of clones (M-34445, M-34450 and M-34455) of T. andersonii maintained at the USDA-ARS National Germplasm Repository, Miami, Florida. One of the progeny had 64 chromosomes, which is typical of T. andersonii, and probably resulted from apomictic reproduction. Karyotypes of the other three progeny indicated a tetraploid Tripsacum genomic constitution (2n = 4x = 72) plus a haploid set of Zea (1n = 1x = 10) chromosomes. Two of these progeny were completely sterile, whereas one (95-51) produced ∼5% seed set when crossed with diploid (2n = 36) T. dactyloides (L.)L. The partially fertile 95-51 produced four progeny, one with 2n = 72 (elimination of 10 Zea chromosomes), two with 2n = 82 (apomictic reproduction) and one with 2n = 100 (sexual polyploidization). Polymerase Chain Reaction - Random Amplified Polymerase DNA analysis verified that T. andersonii accessions from seven countries were genetically uniform, and that its progeny were derived through apomixis and sexual polyploidization. This analysis also confirmed that chromosome elimination, apomixis, and sexual polyploidization reproductive behaviors occur in the T. andersonii derivative 95-51. |
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