Submitted to: United States-Japan Cooperative Program in Natural Resources
Publication Type: Proceedings
Publication Acceptance Date: October 15, 2006
Publication Date: December 20, 2006
Citation: Kindiger, B.K. 2006. Chromosome elimination in lolium multiflorum x festuca arundinaceae hybrids.. United States-Japan Cooperative Program in Natural Resources. 12: 8-12. Interpretive Summary: The development of cool-season, perennial grass forages that are tolerant of the heat and droughts characteristic of the U.S. southern plains is an important objective for the beef industry in this region. Previous studies suggest that the hybridization of annual ryegrass and tall fescue can result in the development of cultivars that exhibit high forage quality and tolerance to environmental stress. At the Grazinglands Research Laboratory near El Reno, OK, an annual ryegrass population was crossed with six tall fescue cultivars adapted to central Oklahoma. Over 300 F1 hybrids were generated and grown for two years. Of these, 86 hybrids survived. These hybrids generated few seed, but those seed that were developed were germinated and grown. Many of these F2 plants were found to have lost both ryegrass and tall fescue chromosomes during seed development and early vegetative growth. Some of the individual plants had leaves and seed heads that resembled both annual ryegrass and tall fescue. The mosaic composition of these individuals was confirmed by DNA fingerprinting methods. Cytogenetic examinations of the offspring generated from the hybrids indicated a loss of approximately 14 of the 28 chromosomes found in their parents. These results suggest that a fertile ryegrass-fescue hybrid population, possessing fewer chromosomes, can be obtained and utilized for the development of new forages that are adapted to the environmental conditions of the southern plains.
Technical Abstract: The generation and development of cool-season perennial grass forages with adaptation to the environmental extremes of the southern plains region of the USA is an important component of the regions stocker calf industry. The hybridization of ryegrass and fescue germplasm has resulted in the development of Festulolium cultivars that combine the superior agronomic and physiological attributes of both species. The implementation of a similar program, utilizing adapted materials selected within the southern plains, should be equally successful. A series of Lolium multiflorum x Festuca arundinaceae F1 hybrids, exhibiting tolerance to the environmental extremes of central Oklahoma, were used to develop a F2 population. Examination of the F2 generation suggested that highly fertile offspring can be readily obtained without doubling the chromosome number of the F1 generation. In addition, examination of the F2 generation suggested that chromosome loss during meiosis and mitosis is a common occurrence. From 86 surviving F1 hybrids, 77 F2 offspring were obtained and were observed to exhibit a Lolium, Festuca or an intermediate Lolium-Festuca phenotype. In some instances, chimeras were identified and confirmed by PCR analysis. Cytogenetic examination of the meiotic behavior within the inflorescence of the chimera sectors was regular and typically indicated the occurrence of seven bivalents. The generation of a fertile F2 generation with a high degree of phenotypic and genotypic variability suggests that these F2 individuals can provide a wide range of new materials for the development and selection of a new class of cool-season perennial grass hybrids.