CYTOLOGICAL AND MOLECULAR EVALUATION OF THE REPRODUCTIVE-BEHAVIOR OF TRIPSACUM-ANDERSONII END A FEMALE FERTILE DERIVATIVE (POACEAE)

Research was conducted to characterize the reproductive behavior of th e highly sterile Tripsacum andersonii Gray and its viable progeny thro ugh breeding, cytological, and molecular studies. Four progeny were ob tained from open-pollinated seeds of clones (M-34445, M-34450 and M-34 455) of T. andersonii maintained at the USDA-ARS National Germplasm Re pository, Miami, Florida. One of the progeny had 64 chromosomes, which is typical of T. andersonii, and probably resulted from apomictic rep roduction. Karyotypes of the other three progeny indicated a tetraploi d Tripsacum genomic constitution (2n = 4x = 72) plus a haploid set of Zea (1n = 1x = 10) chromosomes. Two of these progeny were completely s terile, whereas one (95-51) produced similar to 5% seed set when cross ed with diploid (2n = 36) T. dactyloides (L.)L. The partially fertile 95-51 produced four progeny, one with 2n = 72 (elimination of 10 Zea c hromosomes), two with 2n = 82 (apomictic reproduction) and one with 2n = 100 (sexual polyploidization). Polymerase Chain Reaction - Random A mplified Polymerase DNA analysis verified that T, andersonii accession s from seven countries were genetically uniform, and that its progeny were derived through apomixis and sexual polyploidization. This analys is also confirmed that chromosome elimination, apomixis, and sexual po lyploidization reproductive behaviors occur in the T. andersonii deriv ative 95-51.