Brief communication. Inheritance of resistance in smooth bromegrass to the crown rust fungus

Abstract

Common smooth bromegrass (Bromus inermis Leyss.) is octoploid, 2n = 8x = 56, with a genome structure of AAAAB1B1B2B2. Tetrasomic inheritance patterns have been observed in smooth bromegrass, but disomic inheritance is also expected from cytologic observations. Smooth bromegrass is susceptible to the crown rust fungus (Puccinia coronata Corda.). The objective of this study was to determine the inheritance of smooth bromegrass resistance to P. coronata. Seven smooth bromegrass clones, three susceptible and four resistant, were selfed and crossed in a diallel with bulked reciprocals. Inoculations were made with a population of P. coronata from PL-BDR1 smooth bromegrass. Resistance of smooth bromegrass to this population of P. coronata is complex. At least three genes appear to be involved in this host-pathogen interaction, one tetrasomic dominant gene which determines susceptibility (S) and two dominant genes (R1 and R2) that may be complementary and could be inherited either tetrasomically or disomically. Other genes may be involved in the smooth bromegrass-P. coronata interaction, possibly accounting for the lack of fit to expected ratios of some progeny. Heterogeneity for avirulence phenotype in the pathogen population may also have contributed to lack of fit of some progeny. Multiple resistance genes were detected because a pathogen population, likely consisting of genotypes with different genes for virulence, was used to challenge the host.

Development of a genome-wide multiple duplex-SSR protocol and its applications for the identification of selfed progeny in switchgrass

“…The set of SSR markers selected here are also helpful to identify genotypes, test seed purity, and protect intellectual property in switchgrass. Other forage species with diploid and allopolyploid genome structure were reported as well, including creeping bentgrass ( Agrostis palustri ) [55], colonial bentgrass ( Agrostis capillaries ) [56], perennial ryegrass ( Lolium perenne ) [57], Italian ryegrass ( L. multiflorum ) [57], tall fescue ( Festuca arundinacea ) [58], meadow fescue ( Festuca pratensis ) [59], white clover ( Trifolium repens ) [60], red clover ( Trifolium pretense ) [61], and smooth bromegrass ( Bromus inermis ) [62]. Similar testing can be expanded into these species.…”

Heterosis and Inbreeding Depression for Forage Yield and Fiber Concentration in Smooth Bromegrass

“…Seven smooth bromegrass clones were selected for their susceptible (three clones) or resistant (four clones) reaction to Puccinia coronata Corda (Delgado et al, 2000). The seven clones were selected from four populations: three from Alpha, two from WB19e, and one each from Lincoln and WB88S.…”

“…All seven clones were also self‐pollinated in the greenhouse during the winter of 1997–1998 (Delgado et al, 2000). Smooth bromegrass is a self‐incompatible species with different degrees of incompatibility, so 12 to 18 plants per clone were used for selfing.…”