|Jessup, J - TEXAS A&M UNIV|
Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: August 30, 2007
Publication Date: October 19, 2007
Citation: Jessup, J.L., Jessup, R.W., Burson, B.L. 2007. Genetic variation within Florida paspalum as detected by SSR analysis and flow cytometry [abstract]. American Society of Agronomy. Paper No. 363. Technical Abstract: Florida paspalum (Paspalum floridanum Michx.) is a perennial warm-season bunchgrass native to the southeastern United States. The grass is grazed by livestock and its seed are a source of food for wildlife. Efforts to improve the species through breeding have not been attempted because it is cytologically complex and its method of reproduction is not understood. It is a meiotically irregular polyploid with about 160 chromosomes. Because of irregular meiosis, sexual reproduction should produce plants with a wide range of chromosomes and a highly variable DNA content. The objective of this investigation was to obtain insight as to the method of reproduction of these plants based on the genetic variation and DNA content of the accession and their progeny. Fifty three accessions collected in Texas, Oklahoma, Arkansas, and Louisiana were used in this study. A total of 61 SSRs obtained from a variety of grass species, including Paspalum dilatatum Poir., were utilized to determine genetic variation between plants. Following analysis with NTSYSpc, the average genetic similarity between individual accessions was determined to be 0.64. Diversity between plants was significant enough to individually identify each accession. Individual plants were able to be separately identified in NTSYSpc. Flow cytometry was utilized to determine DNA content variation, which ranged from 11.91 to 13.95 pg. Eight progeny of 10 unique accessions were also studied utilizing both the 18 SSRs and flow cytometry in order to investigate the mode of reproduction in Florida paspalum. Average pairwise genetic similarity across half-sib progeny families of selected accessions ranged from 0.66 to 0.87, with an overall average of 0.76. Chi-square tests of independence were significant for both 1:1 ratios as expected with sexuality and 1:0 ratios as expected with apomixis. These findings suggest that the accessions analyzed may reproduce by facultative apomixis.