''Puccinia melanocephala'' is a fungus and

plant pathogen Plant pathology (also phytopathology) is the scientific study of diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Organisms that cause infectious disease include fungi, oomyc ...

, it is the causal agent of

sugarcane Sugarcane or sugar cane is a species of (often hybrid) tall, Perennial plant, perennial grass (in the genus ''Saccharum'', tribe Andropogoneae) that is used for sugar Sugar industry, production. The plants are 2–6 m (6–20 ft) tall with ...

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 ...

. It was originally found on the leaves of a species of ''

Arundinaria ''Arundinaria'' is a genus of bamboo in the grass family the members of which are referred to generally as cane. ''Arundinaria'' is the only bamboo native to south and southeastern North America, with a native range from Maryland south to Florid ...

'' (cane) in

Assam Assam (; ) is a state in northeastern India, south of the eastern Himalayas along the Brahmaputra and Barak River valleys. Assam covers an area of . The state is bordered by Bhutan and Arunachal Pradesh to the north; Nagaland and Manipur ...

, India. This pathogen was found to also affect multiple species of sugarcane, including ''

Saccharum spontaneum ''Saccharum spontaneum'' (wild sugarcane, Kans grass) is a grass native to the Indian Subcontinent. It is a perennial grass, growing up to three meters in height, with spreading rhizomatous roots. In the Terai-Duar savanna and grasslands, a l ...

'' or wild sugarcane, ''

Saccharum robustum ''Saccharum robustum'', the robust cane, is a species of plant found in New Guinea. Ecology ''Eumetopina flavipes'', the island sugarcane planthopper, a species of planthopper present throughout South East Asia and is a vector for the Ramu stun ...

'', and the most commonly cultivated species ''

Saccharum officinarum ''Saccharum officinarum'' is a large, strong-growing species of grass in the genus '' Saccharum''. Its stout stalks are rich in sucrose, a simple sugar which accumulates in the stalk internodes. It originated in New Guinea, and is now cultivated ...

''. ''Puccinia melanocephala'' can also infect other member of the family

Poaceae Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns an ...

, including some species of bamboo such as ''

Bambusa vulgaris ''Bambusa vulgaris'', common bamboo, is an open-clump type bamboo species. It is native to Indochina and to the province of Yunnan in southern China, but it has been widely cultivated in many other places and has become naturalized in several re ...

''. The first symptoms of sugarcane rust are elongate, yellow-colored leaf spots, roughly 1mm to 4mm in length. The leaf spots gradually become bigger and turn a reddish-brown color. The uredia develop underneath the epidermis where the leaf spots are present. When the uredia become big enough, they break through the epidermis to form the characteristic rust pustules from which uredospores are borne. These pustules can coalesce, resulting in large areas of dead tissue.

Disease cycle

Sugarcane rust is an

autoecious 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 cycl ...

rust, meaning it completes its entire life cycle on the same species of host plant. As mentioned above, uredospores are produced from the pustules that break through the epidermis on the underside of the leaves. Uredospores are the only infectious spores of ''Puccinia melanocephala''. The uredospores disperse from the pustules via wind or rain onto the leaves of a new host sugarcane plant. The uredospores then germinate on the sugarcane leaves, develop appresoria, and infect the new host plant via penetration of the plant's stomata. This cycle can be repeated throughout the year because sugarcane is grown almost exclusively in areas where the climate is conducive to growth of Puccinia melanocephala throughout the year. Puccinia melanocephala infection is non-systemic.

Environment

''Puccinia melanocephala'' develops optimally at temperatures between 16 and 25 degrees Celsius (60.8 to 77 degrees Fahrenheit). However, germination of the infectious uredospores occurs at optimal levels between 21 and 26 degrees Celsius (69.8 to 78.8 degrees Fahrenheit). Germinated uredospores require at least 8 hours of leaf moisture for the germ tube to penetrate the stomata and infect the plant.

Importance

Sugarcane Sugarcane or sugar cane is a species of (often hybrid) tall, Perennial plant, perennial grass (in the genus ''Saccharum'', tribe Andropogoneae) that is used for sugar Sugar industry, production. The plants are 2–6 m (6–20 ft) tall with ...

is a large, edible grass crop native to southeast Asia and many pacific island nations. Throughout history, sugar derived from sugarcane was a luxury due to its rarity, especially in parts of Europe such as England. Today, sugarcane is cultivated in countries with tropical climates all over the world and provides about 80% of the world's sugar supply; the top five sugarcane producing nations are Brazil, India, China, Thailand, and Pakistan. As sugar is now used in a variety of different products, everything from cosmetic sugar scrubs to a countless number of food products. Because of the sheer ubiquity of cane sugar, and also because most of the world's sugarcane is produced in nations with "developing economies", the economic and cultural importance of studying diseases such as sugarcane common rust is exceedingly apparent. ''Puccinia melanocephala'' was claimed to have been used as a

biological weapon A biological agent (also called bio-agent, biological threat agent, biological warfare agent, biological weapon, or bioweapon) is a bacterium, virus, protozoan, parasite, fungus, or toxin that can be used purposefully as a weapon in bioterroris ...

by the US in Cuba during the 1970s.

References

External links

USDA ARS Fungal Database
{{Taxonbar, from=Q149962 Fungal plant pathogens and diseases Sugarcane diseases melanocephala Fungi described in 1907 Taxa named by Paul Sydow Taxa named by Hans Sydow

Disease cycle

Environment

Importance

See also

References

External links