Summary
The Rp1 locus of maize determines resistance to races of the maize rust fungus (Puccinia sorghi). Restriction fragment length polymorphism markers that closely flank Rp1 were mapped and used to study the genetic fine structure and role of recombination in the instability of this locus. Susceptible progeny, lacking the resistance of either parent, were obtained from test cross progeny of several Rp1 heterozygotes. These susceptible progeny usually had non-parental genotypes at flanking marker loci, thereby verifying their recombinational origin. Seven of eight Rp1 alleles (or genes) studied were clustered within about 0.2 map units of each other. Rpl G, however, mapped from 1–3 map units distal to other Rp1 alleles. Rp5 also mapped distally to most Rp1 alleles. Other aspects of recombination at Rp1 suggested that some alleles carry duplicated sequences, that mispairing can occur, and that unequal crossing-over may be a common phenomenon in this region; susceptible progeny from an Rp1 A homozygote had recombinant flanking marker genotypes, and susceptible progeny from an Rp1 DlRp1 F heterozygote showed both possible nonparental flanking marker genotypes.
Similar content being viewed by others
References
Bennetzen JL (1984) Transposable element Mu1 is found in multiple copies only in Robertson's Mutator maize lines. J Mol Appl Genet 2:519–524
Bennetzen JL, Blevins WE, Ellingboe AH (1988a) Cell-autonomous recognition of the rust pathogen determines Rp1-specified resistance in maize. Science 241:208–210
Bennetzen JL, Qin M, Ingels S, Ellingboe AH (1988b) Allele-specific and Mutator-associated instability at the Rp1 disease-resistance locus of maize. Nature 332:369–370
Crute IR (1985) The genetic bases of relationships between microbial parasites and their hosts. In: Fraser RSS (ed) Mechanisms of resistance to plant disease. Martinus Nijhoff and W. Junk, Dordrecht, pp 80–142
Dooner HK (1986) Genetic fine structure of the Bronze locus in maize. Genetics 113:1021–1036
Giese H (1981) Powdery mildew resistance genes in the Ml-a and Ml-k regions on barley chromosome 5. Hereditas 95:51–62
Hagan WL, Hooker AL (1965) Genetics of reaction to Puccinia sorghi in eleven corn inbred lines from Central and South America. Phytopathology 55:193–197
Hooker AL (1969) Widely based resistance to rust in corn. In: Browning JA (ed) Disease consequences of intensive and extensive culture of field crops. Iowa Agr Home Econ Sta Special Rept 64, pp 28–34
Hooker AL, Russell WA (1962) Inheritance of resistance to Puccinia sorghi in six corn inbred lines. Phytopathology 52:122–128
Hulbert SH, Michelmore RW (1985) Linkage analysis of genes for resistance to downy mildew (Bremia lactucae) in lettuce (Lactuca sativa). Theor Appl Genet 70:520–528
Lee BH, Hooker AL, Russell WA, Dickson JG, Flangas AL (1963) Genetic relationships of alleles on chromosome 10 for resistance to Puccinia sorghi in 11 corn lines. Crop Sci 3:24–26
Pryor A (1987) The origin and structure of fungal disease resistance genes in plants. Trends Genet 3:157–161
Saghai-Maroof MA, Soliman KM, Jorgensen RA, Allard RW (1984) Ribosomal DNA spacer-length polymorphisms in barley: Mendelian inheritance, chromosomal location, and population dynamics. Proc Natl Acad Sci USA 81: 8014–8018
Saxena KMS, Hooker AL (1968) On the structure of a gene for disease resistance in maize. Proc Natl Acad Sci USA 68:1300–1305
Shepherd KW, Mayo GME (1972) Genes conferring specific plant disease resistance. Science 175:375–380
Stevens WL (1942) Accuracy of mutation rates. J Genet 43:301–307
Sturtevent AH (1925) The effects of unequal crossing over at the Bar locus in Drosophila. Genetics 10:117–147
Weber D, Helentjaris T (1989) Mapping RFLP loci in maize using B-A translocations. Genetics 121:583–590
WilkinsonDR, Hooker AL (1968) Genetics of reaction to Puccinia sorghi in ten corn inbred lines from Africa and Europe. Phytopathology 58:605–608
Author information
Authors and Affiliations
Additional information
Communicated by E. Meyerowitz
Rights and permissions
About this article
Cite this article
Hulbert, S.H., Bennetzen, J.L. Recombination at the Rp1 locus of maize. Molec. Gen. Genet. 226, 377–382 (1991). https://doi.org/10.1007/BF00260649
Issue Date:
DOI: https://doi.org/10.1007/BF00260649