Puccinia coronata
Encyclopedia
Puccinia coronata is a plant pathogen and causal agent of oat
crown rust
and barley crown rust. The pathogen occurs worldwide infecting both wild and cultivated oats. It is a relatively new disease of barley in North America. It was first found in 1992 in a barley breeding nursery near Clay Center, Nebraska. Since then, crown rust has been found throughout the upper Midwest, with greatest incidence in the central Red River Valley
of North Dakota
and Minnesota
. In that region the alternate host, common buckthorn (Rhamnus cathartica
), grows abundantly in shelter belts and riparian areas. Since 1993, outbreaks of crown rust have occurred on barley and forage grasses at several localities in this region. The extent of yield losses in barley caused by this disease have not been determined. Crown rust posed a threat to barley production, because the first infections in barley occur early in the season from local inoculum.
s
and awns. Extensive chlorosis is often associated with the uredinia. Telia are mostly linear, black to dark brown, and are covered by the host epidermis.
s that infect R. cathartica. Pycnial and aecial stages are produced on the alternate host. Aeciospores from R. cathartica are the primary inoculum for infecting barley. The primary infections, which can occur as early as the three leaf stage of barley in the spring, develop into uredinia. Urediniospores produced in the uredinia repeat the infection process, and the fungus undergoes several cycles of reproduction on barley during the growing season. Spread by wind-borne urediniospores can carry the fungus some distance from the R. cathartica bushes that were the original sources of primary inoculum, although such secondary spread seems much less extensive than that for oat crown rust.
Barley crown rust can infect rye
as well as barley. In addition, it also infects a number of wild grasses including quackgrass (Elytrigia repens), slender wheatgrass (Elymus tranchycaulus), western wheatgrass (Pascopyrum smithii), foxtail barley (Hordeum jubatum
), and several wheatgrasses (Elytrigia
spp.) and wild rye grasses (Elymus
spp. and Leymus
spp.). The fungus readily forms telia on these hosts, which serve as a reservoir of overwintering teliospores. Quackgrass may be the most important reservoir for overwintering telia. This ubiquitous, perennial weed is very susceptible to the rust and is often found growing near Rhamnus.
cultivars currently grown in the northern Great Plains of North America are susceptible to crown rust.
researchers have introduced individual genes that produce proteins believed to recognize crown rust and trigger a defensive response within the plant. http://www.ars.usda.gov/is/pr/2010/100204.htm Because of P. coronata’s quick ability to adapt to resistant strains of oat, researchers have had to turn to a new variety of oat (Avena barbata), which is commonly considered a weed, for new resistant genes. In lab studies A. barbata has done remarkably well in conferring resistance to various strains of crown rust. The main goal of the researchers is to not only confer resistance to crown rust, but also to develop oat varieties with additional desirable traits such as high yield and drought tolerance
.
Oat
The common oat is a species of cereal grain grown for its seed, which is known by the same name . While oats are suitable for human consumption as oatmeal and rolled oats, one of the most common uses is as livestock feed...
crown rust
Rust (fungus)
Rusts are plant diseases caused by pathogenic fungi of the order Pucciniales. About 7800 species are known. Rusts can affect a variety of plants; leaves, stems, fruits and seeds. Rust is most commonly seen as coloured powder, composed off tiny aeciospores which land on vegetation producing...
and barley crown rust. The pathogen occurs worldwide infecting both wild and cultivated oats. It is a relatively new disease of barley in North America. It was first found in 1992 in a barley breeding nursery near Clay Center, Nebraska. Since then, crown rust has been found throughout the upper Midwest, with greatest incidence in the central Red River Valley
Red River Valley
The Red River Valley is a region in central North America that is drained by the Red River of the North. It is significant in the geography of North Dakota, Minnesota, and Manitoba for its relatively fertile lands and the population centers of Fargo, Moorhead, Grand Forks, and Winnipeg...
of North Dakota
North Dakota
North Dakota is a state located in the Midwestern region of the United States of America, along the Canadian border. The state is bordered by Canada to the north, Minnesota to the east, South Dakota to the south and Montana to the west. North Dakota is the 19th-largest state by area in the U.S....
and Minnesota
Minnesota
Minnesota is a U.S. state located in the Midwestern United States. The twelfth largest state of the U.S., it is the twenty-first most populous, with 5.3 million residents. Minnesota was carved out of the eastern half of the Minnesota Territory and admitted to the Union as the thirty-second state...
. In that region the alternate host, common buckthorn (Rhamnus cathartica
Rhamnus cathartica
Rhamnus cathartica , is a species in the family Rhamnaceae, native to Europe, northwest Africa, and western Asia, from the central British Isles south to Morocco, and east to Kyrgyzstan...
), grows abundantly in shelter belts and riparian areas. Since 1993, outbreaks of crown rust have occurred on barley and forage grasses at several localities in this region. The extent of yield losses in barley caused by this disease have not been determined. Crown rust posed a threat to barley production, because the first infections in barley occur early in the season from local inoculum.
Symptoms
Uredinia are linear, light orange, and occur mostly on the leaf blades but occasionally occur also on leaf sheaths, pedunclePeduncle (botany)
In botany, a peduncle is a stem supporting an inflorescence, or after fecundation, an infructescence.The peduncle is a stem, usually green and without leaves, though sometimes colored or supporting small leaves...
s
and awns. Extensive chlorosis is often associated with the uredinia. Telia are mostly linear, black to dark brown, and are covered by the host epidermis.
Disease cycle
Teliospores on barley straw and residue of susceptible grasses left in the field germinate in the spring and produce basidiosporeBasidiospore
A basidiospore is a reproductive spore produced by Basidiomycete fungi. Basidiospores typically each contain one haploid nucleus that is the product of meiosis, and they are produced by specialized fungal cells called basidia. In grills under a cap of one common species in the phylum of...
s that infect R. cathartica. Pycnial and aecial stages are produced on the alternate host. Aeciospores from R. cathartica are the primary inoculum for infecting barley. The primary infections, which can occur as early as the three leaf stage of barley in the spring, develop into uredinia. Urediniospores produced in the uredinia repeat the infection process, and the fungus undergoes several cycles of reproduction on barley during the growing season. Spread by wind-borne urediniospores can carry the fungus some distance from the R. cathartica bushes that were the original sources of primary inoculum, although such secondary spread seems much less extensive than that for oat crown rust.
Barley crown rust can infect rye
Rye
Rye is a grass grown extensively as a grain and as a forage crop. It is a member of the wheat tribe and is closely related to barley and wheat. Rye grain is used for flour, rye bread, rye beer, some whiskeys, some vodkas, and animal fodder...
as well as barley. In addition, it also infects a number of wild grasses including quackgrass (Elytrigia repens), slender wheatgrass (Elymus tranchycaulus), western wheatgrass (Pascopyrum smithii), foxtail barley (Hordeum jubatum
Hordeum jubatum
Hordeum jubatum is a perennials plant species in the grass family Poaceae. It occurs wild mainly in northern North America and adjacent northeastern Siberia. However, as it escaped often from gardens it can be found worldwide in areas with temperate to warm climates, and is considered a weed in...
), and several wheatgrasses (Elytrigia
Elytrigia
Elytrigia is a genus of about 20–40 species of grasses, native to temperate regions of the Old World, in Europe, Asia, and northwest Africa. The species are sometimes included in the related genera Agropyron or Elymus, while species in the genera Pascopyrum and Pseudoroegneria are included in...
spp.) and wild rye grasses (Elymus
Elymus
In Greek and Roman mythology, Elymus was the mythical ancestor of the Elymians, natives of Sicily. Elymus was a Trojan, a natural son of Anchises and a brother of Eryx....
spp. and Leymus
Leymus
Leymus is a genus of the true grass family . The common name for this genus is "wild rye"; however, members of the genus Elymus are also sometimes given the same common name...
spp.). The fungus readily forms telia on these hosts, which serve as a reservoir of overwintering teliospores. Quackgrass may be the most important reservoir for overwintering telia. This ubiquitous, perennial weed is very susceptible to the rust and is often found growing near Rhamnus.
Management
Sources of resistance to crown rust have been identified in barley germplasm from diverse regions, but most malting barleycultivars currently grown in the northern Great Plains of North America are susceptible to crown rust.
Agricultural Research Service
The Agricultural Research Service is the principal in-house research agency of the United States Department of Agriculture . ARS is one of four agencies in USDA's Research, Education and Economics mission area...
researchers have introduced individual genes that produce proteins believed to recognize crown rust and trigger a defensive response within the plant. http://www.ars.usda.gov/is/pr/2010/100204.htm Because of P. coronata’s quick ability to adapt to resistant strains of oat, researchers have had to turn to a new variety of oat (Avena barbata), which is commonly considered a weed, for new resistant genes. In lab studies A. barbata has done remarkably well in conferring resistance to various strains of crown rust. The main goal of the researchers is to not only confer resistance to crown rust, but also to develop oat varieties with additional desirable traits such as high yield and drought tolerance
Drought tolerance
Drought tolerance refers to the degree to which a plant is adapted to arid or drought conditions. Desiccation tolerance is an extreme degree of drought tolerance...
.