Wheat leaf rust caused by Puccinia triticina.
Leaf rust, caused by Puccinia triticina, is the most common rust disease of wheat. The fungus is an obligate parasite capable of producing infectious urediniospores as long as infected leaf tissue remains alive. Urediniospores can be wind-disseminated and infect host plants hundreds of kilometres from their source plant, which can result in wheat leaf rust epidemics on a continental scale. This review summarizes current knowledge of the P. triticina/wheat interaction with emphasis on the infection process, molecular aspects of pathogenicity, rust resistance genes in wheat, genetics of the host parasite interaction, and the population biology of P. triticina.


METHODS
Puccinia triticina Eriks.: kingdom Fungi, phylum Basidiomycota, class Urediniomycetes, order Uredinales, family Pucciniaceae, genus Puccinia.


METHODS
Telial/uredinial (primary) hosts: common wheat (Triticum aestivum L.), durum wheat (T. turgidum L. var. durum), cultivated emmer wheat (T. dicoccon) and wild emmer wheat (T. dicoccoides), Aegilops speltoides, goatgrass (Ae. cylindrica), and triticale (X Triticosecale). Pycnial/aecial (alternative) hosts: Thalictrum speciosissimum (= T. flavum glaucum) and Isopyrum fumaroides.


METHODS
Leaf rust is characterized by the uredinial stage. Uredinia are up to 1.5 mm in diameter, erumpent, round to ovoid, with orange to brown uredinia that are scattered on both the upper and the lower leaf surfaces of the primary host. Uredinia produce urediniospores that are sub-globoid, average 20 microm in diameter and are orange-brown, with up to eight germ pores scattered in thick, echinulate walls.


METHODS
Wheat varieties that are fully susceptible have large uredinia without causing chlorosis or necrosis in the host tissues. Resistant wheat varieties are characterized by various responses from small hypersensitive flecks to small to moderate size uredinia that may be surrounded by chlorotic and/or necrotic zones.


BACKGROUND
USDA Cereal Disease Laboratory: http://www.ars.usda.gov/mwa/cdl.
Bolton
Melvin D
MD
USDA-ARS, Plant Science Research Unit, 411 Borlaug Hall, University of Minnesota, St. Paul, MN 55108, USA.
Kolmer
James A
JA
Garvin
David F
DF
D001487:Basidiomycota / Q000502:physiology*; D054884:Host-Pathogen Interactions; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology*; D018515:Plant Leaves / Q000235:genetics / Q000382:microbiology*; D014908:Triticum / Q000235:genetics* / Q000382:microbiology*