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Selection for growth-rate during asexual and sexual propagation in Phytophthora cactorum

Published online by Cambridge University Press:  14 April 2009

Donald MacIntyre  and
Charles G. Elliott
Donald MacIntyre
Affiliation:
Botany Department, University of Glasgow
Charles G. Elliott
Affiliation:
Botany Department, University of Glasgow
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Selection for high and low growth-rate was carried out during eight generations of asexual propagation by zoospores and seven generations of sexual reproduction by oospores. The fungus has previously been shown to be diploid during its vegetative phase. In the zoospore lines there was no significant variation and no response to selection, except for the occasional appearance of fast-growing sectors. A high line was established from such a sector; in its sexual progeny the inheritance of growth-rate was non-Mendelian. Propagation through self-fertilized oospores released very considerable genetic variation, and both high and low lines responded to selection. At first the variation within families, and the response to selection, increased with succeeding generations, despite the intense inbreeding. In later generations the high line became less variable, and the progeny oospore cultures resembled the fast-growing sectors. It is concluded that growth-rate is controlled by a polygenic system and by cytoplasmic determinants, a mutant form of which is responsible for the fast-sectoring phenotype.

Type
Research Article
Information
Genetics Research , Volume 24 , Issue 3 , December 1974 , pp. 295 - 309
Copyright
Copyright © Cambridge University Press 1974

References

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