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Genetic analysis of crown rust (Puccinia coronata f. sp. lolii) resistance in a perennial ryegrass (Lolium perenne) genotype

Author:
Schubiger, Franz Xaver, Boller, Beat
Source:
Euphytica 2017 v.213 no.8 pp. 167
ISSN:
0014-2336
Subject:
Lolium perenne, Puccinia coronata, backcrossing, crown rust, cultivars, diploidy, dominant genes, genetic analysis, genotype, growth chambers, inheritance (genetics), plant breeding, progeny
Abstract:
In order to study the inheritance of resistance to crown rust (Puccinia coronata f. sp. lolii) in perennial ryegrass (Lolium perenne), we crossed a resistant, diploid genotype (A6128/05) with a susceptible genotype of the cultivar Aurora to generate a F₁ population. Individuals of the F₁ population were screened for their response to three single-pustule isolates (SPI) of crown rust in a detached-leaf segment test under growth chamber conditions. Out of the F₁ population, we selected two genotypes (I and II) based on the reaction to SPI of crown rust: genotype I was resistant to SPI A, D and F. Genotype II was resistant to SPI A, but susceptible to SPI D and F. Both genotypes were backcrossed with a second, susceptible Aurora genotype to generate two F₂ populations. A resistant genotype out of each of the two F₂ populations was used to generate a F₃ population by backcrossing with a susceptible Aurora genotype. In the F₂ and F₃ populations, derived from a cross with the genotype I, a good fit to a segregation ratio of 1R:1S (resistant:susceptible) was observed for the three SPI A, D and F. The frequency of resistant and susceptible plants within the F₂ and F₃ populations, derived from the genotype II, resulted in a ratio of 1R:1S for SPI A. In contrast, the F₂ and F₃ progeny was susceptible to SPI D and F. These results provide evidence that at least two different dominant genes for crown rust resistance occur in the resistance donor A6128/05.
Agid:
5745350