Evidence for outcrossing in Phytophthora sojae and linkage of a DNA marker to two avirulence genes

Whisson, S. C., Drenth, A., Maclean, D. J. and Irwin, J. A. G. (1994) Evidence for outcrossing in Phytophthora sojae and linkage of a DNA marker to two avirulence genes. Current Genetics, 27 1: 77-82. doi:10.1007/BF00326582


Author Whisson, S. C.
Drenth, A.
Maclean, D. J.
Irwin, J. A. G.
Title Evidence for outcrossing in Phytophthora sojae and linkage of a DNA marker to two avirulence genes
Journal name Current Genetics   Check publisher's open access policy
ISSN 0172-8083
1432-0983
Publication date 1994-12
Sub-type Article (original research)
DOI 10.1007/BF00326582
Volume 27
Issue 1
Start page 77
End page 82
Total pages 6
Place of publication Berlin / Heidelberg
Publisher Springer
Language eng
Subject 060704 Plant Pathology
Formatted abstract
Two genetically different isolates of the homothallic Oomycete, Phytophthora sojae, were demonstrated to outcross and form hybrid oospores after co-culturing in vitro. Random amplified polymorphic DNA (RAPD) markers revealed ten hybrids among 354 oospores analysed. One F1 hybrid was allowed to self fertilise and produce an F2 population of 247 individuals. Among 53 F2 individuals, selected at random, 18 polymorphic RAPD markers were observed to segregate at near 3:1 Mendelian ratios, consistent with segregation for dominant alleles at single loci. Segregation of virulence against soybean resistance genes Rps1a, 3a, and 5 revealed that the avirulence genes Avr1a, 3a and 5 were dominant to virulence. Avirulence against these three resistance genes appeared to be conditioned by one locus for Avr1a and two independent, complementary dominant loci for both Avr3a and Avr5. Segregation of virulence against Rps6 was in the ratio of 1:2:1 (avirulent:mixed reaction:virulent), suggesting a semi-dominant allele at a single locus. Two avirulence genes and one RAPD marker formed one linkage group, in the order Avr3a, OPH4-1, Avr5, each separated by approximately 5 cM. Our results confirm that outcrossing occurred between the parental isolates, and that sexual recombination under field conditions may play an important role in generating and maintaining genetic diversity in populations of P. sojae.
Keyword Phytophthora megasperma f. sp. glycinea
Avirulence
Gene-for-gene
RAPD
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Biological Sciences Publications
 
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