Submitted to: Plant Genetic Resources International Board Newsletter
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/29/2005
Publication Date: 12/12/2005
Citation: Pitman, W.D., Croughan, S.S., Nash, J.L., Venuto, B.C. 2005. Somaclonal variation in seed germination of Dallisgrass biotypes. Plant Genetic Resources International Board Newsletter. 3(3):414-420. Interpretive Summary: Dallisgrass is an important pasture grass in much of the humid coastal region of southeastern United States. However, its use is often limited by poor seed quality resulting in establishment difficulties. Due to its unique non-sexual reproduction, common dallisgrass has not been responsive to traditional plant improvement approaches. Recent research has shown potential for some improvement in forage production and plant persistence with hexaploid (6 sets of chromosomes) varieties of dallisgrass. Regeneration of plants using tissue-culture has also produced some variation in seed germination of common dallisgrass. Similar techniques were applied to several sources of hexaploid dallisgrass. Plants were regenerated in tissue culture and seed from these plants was evaluated in replicated germination trials to determine whether these plants demonstrated any agronomic improvement. Eight germination trials included 299 regenerated plants with 57 of these being duplicate entries among trials. Germination did not differ among parent sources of the regenerated plants. However, within a particular parental source, germination differed and a few individuals exceeded germination percentage of their parent. Individual regenerated plants with agronomic potential and high percentage seed germination were identified and will be available for further research and cultivar improvement.
Technical Abstract: Dallisgrass (Paspalum dilatatum Poir.) is an important pasture grass on moist fertile sites in warm climates, however, it is limited in use by periodic low seed quality and resulting erratic availability and establishment difficulties. Due to apomictic reproduction, common pentaploid dallisgrass has not been responsive to traditional plant improvement approaches. Recent research has shown potential for some improvement in forage production and plant persistence with apomictic hexaploid varieties of dallisgrass. Tissue-culture regeneration has been reported to produce somaclonal variation in seed germination of common pentaploid dallisgrass and has recently resulted in availability of potentially useful regenerants of hexaploid dallisgrass. Seed of selected plants from both field and greenhouse environments was evaluated in replicated germination trials to determine whether hexaploid tissue-culture regenerants responded similar to regenerants from common dallisgrass and to determine whether regenerants expressing potential agronomic usefulness as indicated by preliminary observations differed in germination. The eight germination trials included 299 regenerants with 57 of these being duplicate entries among trials. Germination did not differ among sources of regenerants. Within sources germination differed among regenerants with a few individuals exceeding germination percentage of parent lines in one evaluation of greenhouse-produced seed. Individual regenerants with agronomic potential and high percentage seed germination were identified. The results demonstrate that tissue-culture regeneration can be used to produce improved germination in agronomically useful genotypes of apomictic dallisgrass and suggest that such potential may exist for other recalcitrant plant species.