|SCHWARTZ, BRIAN - University Of Georgia
|HANS, CHRISTIAN - University Of Georgia
|CONTRERAS, RYAN - Oregon State University
|JACKSON, SCOTT - University Of Georgia
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2013
Publication Date: 5/1/2013
Citation: Schwartz, B.M., Harris-Shultz, K.R., Hans, C.S., Contreras, R.N., Jackson, S.A. 2013. Creation of hexaploid and octaploid zoysiagrass using colchicine and breeding. Crop Science. 53:2218-2224.
Interpretive Summary: Zoysiagrass is used primarily as a warm-season turfgrass for lawns, parks, and golfing surfaces in the warm-humid and transitional climatic regions of the United States. Although zoysiagrass has high heat and drought tolerance, it is slow growing and thus multiple years are needed to establish from plugs. Increases in a plants ploidy level (or chromosome) number can result in plants with increased growth rates and larger vegetative structures as compared to unaltered plants. This study used the chemical cochicine to induce polyploidy in tetraploid (2n=4x=40) zoysiagrass. Four plants were identified that were octaploids (2n=8x=80) and these were crossed with the zoysiagrass cultivar Meyer to form zoysiagrass plants that are hexaploids (2n=6x=60). These polyploids are being evaluated for increased vegetative growth rates.
Technical Abstract: Zoysiagrasses (Zoysia Willd.) are a slow growing, primarily tetraploid (2n = 4x = 40) turfgrass that can be successfully managed with less input than many other warm-season turfgrasses. Despite extensive genetic and morphological variation, genotypes with the ability to recuperate quickly from damage are rare. Therefore, an effort to increase vegetative growth rates in ‘Zenith’ zoysiagrass by inducing higher polyploidy using six colchicine seed treatments began in 2009. Seedlings that germinated after exposure to these treatments were screened using flow cytometry for genome size changes. Four putative octaploids and one cytochimera were identified. Average stomata length of the four colchicine induced putative octaploids were 28% larger than that of Zenith, but the stomata length of the cytochimera was unaltered. Pollen diameter of the four putative octaploids was larger than that of Zenith and the cytochimera. Pollen stainability was relatively unchanged by the colchicine treatments. Furthermore selfing of 09-TZ-103 (putative M0 octaploid) and crossing of 09-TZ-103 with ‘Meyer’ led to the development of M1 hexaploid genotypes. These results support that DNA content of the L-I (epidermis), L-II (germ line), and L-III (adventitious roots) histogenic layers of Zoysia can be manipulated with colchicine and breeding. Evaluation of the turfgrass performance of these polyploids should be carried out to determine the value of this breeding procedure for improvement of zoysiagrass.