Wheat yellow rust (''Puccinia striiformis''
f.sp. ''tritici''), also known as wheat stripe rust, is one of the three major
wheat
Wheat is a group of wild and crop domestication, domesticated Poaceae, grasses of the genus ''Triticum'' (). They are Agriculture, cultivated for their cereal grains, which are staple foods around the world. Well-known Taxonomy of wheat, whe ...
rust
Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture. Rust consists of hydrous iron(III) oxides (Fe2O3·nH2O) and iron(III) oxide-hydroxide (FeO(OH) ...
diseases, along with
stem rust of wheat (''Puccinia graminis'' f.sp. tritici) and
leaf rust (''Puccinia triticina'' f.sp. tritici).
History
As R.P. Singh, J. Huerta-Espino, and A.P. Roelfs say in their 2002 comprehensive review of literature on the wheat rusts for UN
FAO
The Food and Agriculture Organization of the United Nations; . (FAO) is a List of specialized agencies of the United Nations, specialized agency of the United Nations that leads international efforts to defeat hunger and improve nutrition ...
:
Although Gadd first described stripe rust of wheat in 1777, it was not until 1896 that Eriksson and Henning (1896) showed that stripe rust resulted from a separate pathogen, which they named ''P. glumarum''. In 1953, Hylander et al. (1953) revived the name ''P. striiformis''.
A stripe rust outbreak in northwest Syria contributed to the beginning of the
Syrian Civil War by increasing food prices.
Life cycle
Other cereal rust fungi have macrocyclic,
heteroecious
A heteroecious parasite is one that requires at least two hosts. The ''primary host'' is the host in which the parasite spends its adult life; the other is the ''secondary host''. Both hosts are required for the parasite to complete its life cy ...
life cycles, involving five spore stages and two
phylogenetically
In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical data ...
unrelated hosts. ''P. striiformis'' was thought to be
microcyclic for centuries until 2009, when a team of scientists at the USDA-ARS
Cereal Disease Lab led by Yue Jin confirmed that barberry (''
Berberis
''Berberis'' (), commonly known as barberry, is a large genus of deciduous and evergreen shrubs from tall, found throughout temperate and subtropical regions of the world (apart from Australia). Species diversity is greatest in South America a ...
'' and ''
Mahonia
''Mahonia'' is a formerly accepted genus of approximately 70 species of shrubs or, rarely, small trees with evergreen leaves in the family Berberidaceae, native to eastern Asia, the Himalaya, North America, and Central America. They are closely ...
'' spp.) is an alternate host.
Barberry was known as an alternate host of the closely related stem rust (''
Puccinia graminis
Stem rust, also known as cereal rust, black rust, red rust or red dust, is caused by the fungus ''Puccinia graminis'', which causes significant disease in cereal crops. Crop species that are affected by the disease include bread wheat, durum whe ...
'') and for many years, when infection was observed on barberry, it was assumed to be stem rust. (Then ''P. striiformis'' was accidentally discovered to ''also'' have the same alternate host when scientists observed rust infection on various
barberry
''Berberis'' (), commonly known as barberry, is a large genus of deciduous and evergreen shrubs from tall, found throughout temperate and subtropical regions of the world (apart from Australia). Species diversity is greatest in South America a ...
species, and inoculated spores of this unknown rust onto
Poaceae
Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos, the grasses of natural grassland and species cultivate ...
hosts.
Kentucky Bluegrass
''Poa pratensis'', commonly known as Kentucky bluegrass (or blue grass), smooth meadow-grass, or common meadow-grass, is a perennial species of grass native to practically all of Europe, North Asia and the mountains of Algeria, Morocco, and Tuni ...
was the only one to show infection. The