Recurrent Selection for Partial Resistance to Crown Rust in Oat

Abstract

the absence of significant genetic interactions between host and pathogen genotypes (Parlevliet, 1985), the use Crown rust (caused by the fungus Puccinia coronata Cda. f. sp.of this type of resistance in crop cultivars should prevent avenae Eriks.) is a major disease of cultivated oat (Avena sativa L.). Partial resistance is a form of incomplete resistance characterized by a major shifts in the composition of the pathogen populareduced rate of epidemic development and is potentially more durable tion increasing the durability of the disease resistance than complete race-specific resistance. Four rapid cycles of selection (Geiger and Heun, 1989). for partial crown rust resistance were conducted in an oat recurrent Recurrent selection is a population improvement proselection population after the completion of the seventh cycle of cedure that increases the frequency of desirable alleles selection for grain yield. The objectives of this research were to: (i) through repeated cycles of selection and systematic redetermine the effectiveness of rapid cycle recurrent selection for parcombination. This breeding method has been widely tial crown rust resistance; (ii) assess the indirect effect on grain yield, used for improving quantitative traits in cross-pollinated flowering date, and plant height; and (iii) estimate phenotypic and crops. The expression of partial resistance to fungal genetic correlations between traits and broad-sense heritabilities. Recurrent selection parents and check cultivars were evaluated in six pathogens is usually controlled by several genes with environments. Four cycles of selection for partial resistance reduced additive gene action (Veillet et al., 1996; Geiger and the area under the disease progress curve (AUDPC) 42%. This in- Heun, 1989;Parlevliet, 1978). Although these attributes creased resistance was not reflected in higher grain yields under modsuggest that recurrent selection could be an appropriate erate crown rust epidemics, but it produced a 4.7% grain yield gain and effective breeding method for improving disease per cycle in an environment with a severe rust infection. Selection resistance in plants, it has received only limited attention for partial resistance indirectly delayed the flowering date by 2 d. in self-pollinated crops. Recurrent selection has been Entry mean broad-sense heritability estimates were intermediate (41used successfully to increase the resistance in soybean 64%) for AUDPC. Our results show the usefulness of rapid cycle [Glycine max (L.) Merr.] to Phytophthora rot (caused recurrent selection as a population improvement procedure capable of effectively increasing the level of partial resistance to crown rust by Phytophthora megasperma Drechs. f. sp. glycinea in a high-yielding oat population.Kuan and Erwin) (Walker and Schmitthenner, 1984), in barley (Hordeum vulgare L.) to leaf rust (caused by Puccinia hordei Otth.) (Parlevliet and Van Ommeren, 1988;Reinhold et al., 1993), and powdery mildew J.E.

Inheritance of resistance to oat crown rust in recombinant inbred lines

“…However, Pc68/5*Starter is a near isogenic line and might have another resistance gene in addition to Pc68, which would originate from the cultivar Starter. This cultivar demonstrated a degree of resistance upon release in the U.S. (Stuthman et al, 1990), but now it is considered highly susceptible (Díaz-Lago et al, 2002;Leonard, 2002;Leonard, 2003). If the additional gene for resistance was from the genotype Pc68/5*Starter, the resistant recombinant lines would be expected to exhibit levels of FS and AUDPC*c that would be very similar to the resistant parent.…”

Oat Fungal Diseases and the Application of Molecular Marker Technology for Their Control

“…The use of recurrent selection for partial resistance in oat as a means to provide protection against Pca has been reported in several studies (Díaz-Lago et al 2002 ;Long et al 2006 ). Among the various resistance breeding strategies, Holland and Munkvold ( 2001 ) considered gene pyramiding and selection for partial resistance to be more advantageous than single gene resistance and complete resistance (race-specifi c).…”

“…A number of breeding techniques are recommended to acquire durable resistance. Among these are recurrent selection, which, by defi nition, is increasing the frequency of desirable alleles and consequently gains in the population due to repeated cycles of selection and recombination of selected lines (Díaz-Lago et al 2002 ). The authors demonstrated the usefulness of rapid cycle recurrent selection as a population improvement procedure capable of effectively increasing the level of partial resistance to crown rust in an adapted and high-yielding oat population.…”

Evaluating landrace oats (Avena sp.) collected in Tunisia for crown rust resistance under natural infection

“…Breeding for complete racespecific resistance has been the primary control measure for this disease (Simon 1985). However, this strategy usually provides protection for limited period of time (Diaz-Lago et al 2002). Alternative types of resistance, capable of providing longer lasting cultivars, are necessary, and partial resistance is currently being explored as one.…”