Creation and characteristics of tetraploid and mixoploid centipedegrass

Authors: Sapkota, Suraj; KAUR, RAVNEET - University Of Georgia; Harris-Shultz, Karen; Wang, Hongliang; KOO, DAL-HOE - Kansas State University; NABUKALU, PHEONAH - The Land Institute; JESPERSEN, DAVID - University Of Georgia

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/20/2023
Publication Date: 6/8/2023
Citation: Sapkota, S., Kaur, R., Harris-Shultz, K.R., Wang, H., Koo, D., Nabukalu, P., Jespersen, D. 2023. Creation and characteristics of tetraploid and mixoploid centipedegrass. Crop Science. 63:2569-2582. https://doi.org/10.1002/csc2.21011.
DOI: https://doi.org/10.1002/csc2.21011

Interpretive Summary: Centipedegrass, grown in the southern U.S., is a low maintenance turfgrass used for home lawns, parks, and along highways. In the U.S., centipedegrass is genetically and morphologicaly similiar as most of the centipedegrass grown originates from a single accession from China introduced as seed collected by the USDA plant explorer Frank Meyer in 1916. To enhance morphological and genetic variability, polyploid lines were created using irradiation and tissue culture. After three years of continuous propagation, two lines were found to be tetraploids and one line was found to be a mixaploid (2x, 4x). The tetraploids were genotyped and were found to be unique. Six tetraploid, mixoploid, and diploid lines were evaluated in a greenhouse over two years for morphological and physiological traits. Tetraploid lines had larger stomates (pores that control gas exchange including water vapor) and wider leaves. The two tetraploid lines differed between each other for multiple morphological and physiological traits. These tetraploid centipedegrass lines may be of interest to consumers that prefer the wider leaves of St. Augustinegrass but are looking for low maintenance and chinch bug resistant alternatives.

Technical Abstract: Ploidy manipulation has been used in many crop improvement programs to develop plant species with wider adaptability and desirable traits. The objectives of this study were to create stable tetraploid centipedegrass (Eremochloa ophiuroides (Munro) Hack.), lines and evaluate them for beneficial traits. To generate polyploid lines, ‘TifBlair’ (2n=2x=18) seeds were exposed to gamma radiation and callus was generated using tissue culture, exposed to glyphosate and regenerated into plantlets. After five years of continuous propagation, two lines, Hongliang Wang (HW)16 and HW123, were found to be tetraploid, and one line, HW61, was found to be a mixoploid using flow cytometry and chromosome counts. Nuclear DNA contents for diploid and tetraploid lines ranged from 1.97-2.10 and 4.14-4.30 pg-2C, respectively. Ten centipedegrass lines were genotyped using seven simple sequence repeat markers and clustered by origin (derived from TifBlair or the University of Georgia breeding program). Six lines were evaluated for morphological and physiological traits under greenhouse conditions. Trait evaluation showed that tetraploid lines had larger stomata and leaf width and reduced stomatal density. For all other traits evaluated under greenhouse conditions, although significant differences were observed between lines, no consistent differences separated diploid and tetraploid lines. Between the tetraploid lines, HW16 had higher evapotranspiration, percent green cover, and relative water content than HW123, whereas HW123 had a higher average clipping yield and root width than HW16. In conclusion, irradiation and tissue culture are valuable techniques for the generation of stable polyploid lines, and an increased ploidy level led to larger vegetative structures in centipedegrass.