Puccinia coronata

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Puccinia coronata
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Fungi
Division: Basidiomycota
Class: Pucciniomycetes
Order: Pucciniales
Family: Pucciniaceae
Genus: Puccinia
Species:
P. coronata
Binomial name
Puccinia coronata
Corda (1837)
Synonyms

Aecidium crassum

Pers.
(1801)
Aecidium rhamni
J.F.Gmel.
(1792)
Puccinia calamagrostidis
P.Syd.
(1892)
Puccinia coronata f. agrostidis Erikss. (1894)
Puccinia coronata f.sp. alopecuri P.Syd. &
Syd.
(1903)
Puccinia coronata f. sp. avenae P.Syd. & Syd. (1903)
Puccinia coronata f.sp. festucae P.Syd. & Syd. (1903)
Puccinia coronata f.sp. holci P.Syd. & Syd. (1903)
Puccinia coronata f.sp. lolii P.Syd. & Syd. (1903)
Puccinia coronata var. arrhenatheri Kleb.
Puccinia coronata var. calamagrostis W.P.Fraser & Ledingham (1933)
Puccinia coronata var. festucae Erikss.
Puccinia coronata var. holci Kleb.
Puccinia coronata var. lolii Beeynck (1853)
Puccinia lolii E.Nielsen (1875)
Puccinia rhamni (J.F.Gmel.)
Wettst.

Solenodonta coronata (Corda) Syd. (1921)

Puccinia coronata is a plant pathogen and causal agent of oat and barley crown rust. The pathogen occurs worldwide, infecting both wild and cultivated oats. Crown rust poses a threat to barley production, because the first infections in barley occur early in the season from local inoculum.[1] Crown rusts have evolved many different physiological races within different species in response to host resistance. Each pathogenic race can attack a specific line of plants within the species typical host. For example, there are over 290 races of P. coronata.[2] Crops with resistant phenotypes are often released, but within a few years virulent races have arisen and P. coronata can infect them.[3]

Symptoms

Uredinia are linear, light orange, and occur mostly on the leaf blades but occasionally occur also on

leaf sheaths, peduncles
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.[4] Although infection by crown rust does not usually kill whole plants, it does kill individual leaves of the plants. Necrotic areas of infected leaves reflect tissue death. The expansion of disease-dependent chlorosis and necrosis greatly reduces photosynthetic processes and the overall physiological functioning of the infected plant, which in turn reduces growth and crop yields.[5] In addition, if plants are badly infected, they become more sensitive to drought conditions which can cause death.[6]

Disease cycle

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.[4] In fact, P. c. f. sp. avenae can remain viable over dispersal distances of several hundred miles.[6]

Barley crown rust can infect

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.

Intra-specific classification

Uredinial/telial stages also occur on a wide range of grass species (Poaceae) in the genera

s.str. is further divided into two varieties: P. coronata var. avenae and P. coronata var. coronata. The former is composed of two formae speciales: P. coronata var. avenae f. sp. avenae and P. coronata var. avenae f. sp. graminicola. The crown rust pathogen on oats belongs to P. coronata var. avenae f. sp. avenae.[7][8]

Management

Sources of resistance to crown rust have been identified in barley germplasm from diverse regions, but most malting barley cultivars currently grown in the northern Great Plains of North America are susceptible to crown rust.[1] Typically P. coronata can overcome resistant gene within five years, making it difficult for researchers to control its damaging effects on the oat production industry. Agricultural Research Service researchers have introduced individual genes that produce proteins believed to recognize crown rust and trigger a defensive response within the plant.[9] 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 (A. 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.[9]

History of study

Research into P. coronata on A. sativa/oat crown rust has been foundational to the understanding and definition of

"tolerance" in phytopathology. In 1958 Caldwell et al. defined tolerance as that which "enabl[es] a susceptible plant to endure severe attack by a rust fungus without sustaining severe losses in yield or quality." Although they noted that most interest was in breeding for hypersensitive responses, they located, differentiated, quantified, and defined "tolerance" for the first time in cultivars prevalent in the United States.[10][11][12]

See also

References

  1. ^ a b "Barley crown rust". Agricultural Research Service. United States Department of Agriculture. 2021-02-14. Retrieved 2021-02-14.
  2. Plant Disease Reporter
    . 48 (10): 763–766.
  3. doi:10.1080/07060669409500787
    .
  4. ^ a b Disease Cycle
  5. PMID 36610799
    .
  6. ^ a b "Oat crown rust". Cereal Disease Laboratory. United States Department of Agriculture | Agricultural Research Service. Retrieved 19 October 2015.
  7. doi:10.1007/s11557-012-0814-1
    .
  8. ^ Urban, Z.; J. Marková (1993). "The rust fungi of grasses in Europe. I. Puccinia coronata Corda". Acta Univ Carol. 37: 93–147.
  9. ^ a b "ARS Scientists Turn to a Wild Oat to Combat Crown Rust". Agricultural Research Service. United States Department of Agriculture. 2021-02-14. Retrieved 2021-02-14.
  10. PMID 32403981
    .
  11. PMID 28044057
    .
  12. ISSN 0066-4286
    .

External links
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