Colchicine-Induced Tetraploidy in Centipedegrass.

Centipedegrass (Eremochloa ophiuroides) is a low maintenance, diploid (2n = 2x = 18) turfgrass species that is well adapted to sandy, acidic soils in the southern United States.  Morphological variation and differential responses to distinct environmental conditions can be seen on an individual plant basis in this species, but phenotypic and genotypic variation is relatively small on the population level.  Therefore, a laboratory and glasshouse study was initiated in the spring of 2009 to induce polyploidy in ‘TifBlair’ centipedegrass using six colchicine seed pre-treatments which included soaking seeds in 0.025%, 0.05%, and 0.1% colchicine solutions for one week prior to planting.  The remaining three treatments were identical except that seeds were soaked in water for one week prior to the addition of colchicine.  Percent germination of seed in the untreated control was significantly greater (71%) than that of the six colchicine treatments which ranged from 24 to 36%.  Seedling ploidy levels were determined using flow cytometry where one tetraploid and one cytochimera were identified, both from the water/0.1% colchicine treatment.  Each of these single plants represents 0.2% of the total number of treated seeds.  Leaf stomata guard cell length of the induced tetraploid were 12% larger than that of TifBlair, but there was not a significant change in leaf stomata guard cell length in the cytochimera.  These data support that DNA contents of the L-I and L-III histogenic layers have been doubled in the tetraploid genotype, but that the L-I histogenic layer of the cytochimera is still diploid.  Seedheads were not observed during 2009 to verify whether or not the L-II histogenic layers were also affected.  Use of induced polyploidy will be studied further to determine its value in the breeding and improvement of centipedegrass.