Loss of genetic diversity associated with selection for resistance to sorghum midge in Australian sorghum
- 133 Downloads
In recent years, hybrids with levels of resistance to sorghum midge (Stenodiplosis sorghicola Coquillett) have become available to Australian sorghum producers. These hybrids have been readily accepted to the extent that more than 80% of the sorghum growing area was planted to hybrids with some level of midge resistance by 1995. Since selection for resistance to sorghum midge is one of the primary objectives of Australian sorghum breeding programs, the relationship between resistance and genetic diversity was investigated.
Genetic diversity and heterozygosity were assessed using restriction fragment length polymorphism analysis among 26 grain sorghum hybrids grown commercially in Australia.
The genetic distances between each sorghum hybrid and a standard highly resistant hybrid were found to be strongly negatively correlated to hybrid midge resistance ratings (r = - 0.77, p < 0.001). In addition, the average heterozygosity of each hybrid was correlated with their midge resistance ratings (r = - 0.54, p < 0.01).
The results indicate that the move to midge resistant hybrids has been associated with a narrowing of the genetic diversity and average heterozygosity of commercial sorghum hybrids. Repeated use of particular elite parent lines, linkage drag and genetic drift are likely to have contributed to this decline. This reduction in genetic diversity may have implications for the genetic vulnerability of sorghum in Australia and the rate of progress in breeding for yield.
Unable to display preview. Download preview PDF.
- Agrawal, B.L., H.C. Sharma, C.V. Abraham & P. Vidyasagar, 1986. Screening sorghum for midge resistance. In: Proceedings of the First Australian Sorghum Conference, pp. 7.1-7.9. Gatton, QLD.Google Scholar
- Berquist, R.R., P. Rotar & W.C. Mitchell, 1974. Midge and anthracnose head blight resistance in sorghum. Trop Agric 51: 431-535.Google Scholar
- Duncan, R.R., P.J. Bramel-Cox & F.R. Miller, 1991. Contributions of introduced sorghum germplasm to hybrid development in the USA. Crop Science Society of America special publication no 17. 17: 69-101.Google Scholar
- Franzmann, B.A., D.G. Butler, R.G. Henzell, D.S. Fletcher & J.H. Cutler, 1996. A sorghum industry scheme assigning midge resistance levels to commercial hybrids. In: M.A. Foale, R.G. Henzell & J. Kneipp (Eds.), Proceedings of the Third Australian Sorghum Conference, pp. 359-363. Australian Institute of Agricultural Science Occasional Publication 93. Melbourne, Australia.Google Scholar
- Goldshalk, E.B., M. Lee & K.R. Lamkey, 1990. Relationship of restriction fragment length polymorphisms to single-cross hybrid performance of maize. Theor Appl Genet 80: 273-280.Google Scholar
- Henzell, R.G., R.L. Brengman, F.D. Page, D.S. Fletcher, L. Van Slobe & G. Foster, 1986. Breeding for midge resistance in grain sorghum in Queensland. In: M.A. Foale & R.G Henzell (Eds.), Proceedings of the First Australian Sorghum Conference, pp. 7.10-7.18. Gatton, QLD, Feb 1986.Google Scholar
- Peterson, G.C., 1995. Breeding for resistance to sorghum midge in the USA. In: K.F. Nwanze & O. Youm (Eds.), Panicle Insect Pests of Sorghum and Pearl Millet, pp. 149-157. Proceedings of an International Consultative Workshop ICRISAT. Pantancheru, India.Google Scholar
- Poelman, J.M., 1987. Breeding field crops. AVI Pub Co., Wesport, Connecticut.Google Scholar
- Simmonds, N.W., 1979. Principles of Crop Improvement. Longman, London and New York.Google Scholar
- Sneep, J. & A.J.T. Hendriksen, 1979. Plant Breeding Prespectives. Centre for Agricultural Publishing and Documentation. Wageningen. The Netherlands.Google Scholar
- Tao, Y., J.M. Manners, M.M. Ludlow & R.G. Henzell, 1993. DNA polymorphisms in grain sorghum Sorghum bicolorL. Moench. Theor Appl Genet 86: 679-688.Google Scholar
- Tao, Y., C.L. McIntyre & R.G. Henzell, 1996. Application of molecular markers to Australian sorghum breeding programs. I. Construction of a RFLPmap using sorghum recombinant inbred lines. In: M.A. Foale, R.G. Henzell & J. Kneipp (Eds.), Proceedings of the Third Australian Sorghum Conference, pp. 359-363. Australian Institute of Agricultural Science Occasional Publication 93. Melbourne. Australia.Google Scholar
- Teetes, G.L. & J.W. Johnson, 1978. Insect resistance in sorghum. In: Proceedings 33rd Annual Corn and Sorghum Research Conference, pp. 214. Chicago, Ill.Google Scholar
- Widstrom, N.W., B.R. Wiseman & W.W. McMillan, 1972. Some gene effects conditioning resistance to midge and webworm injury in sorghum. Sorghum Newslett 15: 22-23.Google Scholar