|PRICE, H - TAMU
Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: 8/10/2005
Publication Date: 10/25/2005
Citation: Burson, B.L., Price, H.J. 2005. Nuclear DNA content of Florida paspalum [abstract]. American Society of Agronomy. Paper No. 706a.
Technical Abstract: Florida paspalum (Paspalum floridanum Michx.) is a robust, rhizomatous, perennial grass that is native to the southeastern United States. Cattle readily graze the grass, and its seed are a source of food for wildlife. Efforts to improve the species through breeding have not been attempted because its complex cytology and reproductive behavior are not well established. Its reported chromosome number ranges from 2n=12x=120 to 2n=18x=180. Meiosis is very irregular with as many as 80 laggards at anaphase I. It appears that most of these lagging chromosomes are not incorporated into the developing gametes. In spite of this high number of chromosomes and the accompanying meiotic irregularities, most plants are highly fertile. This suggests the species reproduces by apomixis. However, studies of megasporogenesis and megagametogenesis indicate the species is sexual. Because of irregular meiosis, sexual reproduction should result in plants with a wide range of chromosomes; whereas, apomictic reproduction should produce plants with similar chromosome numbers. In order to understand which reproductive process occurs in this species, flow cytometry was used to measure the nuclear DNA content and predict the ploidy levels of different Florida paspalum accessions. Germplasm collected from different geographical regions in Arkansas, Louisiana, Oklahoma, and Texas was used for this study. There was not a large variation in DNA content among accessions. Of the populations studied, DNA content of the individual plants ranged from 11.83 pg to 12.95 pg with a mean of 12.16 pg (SD=0.52). Because of the extreme meiotic irregularities in this species, more variation in DNA content would be expected if the species reproduced sexually. This suggests that either some unique chromosome restoring mechanism or a form of apomixis is involved.