| Melampsora lini | |
|---|---|
 | |
| Teleutospores of Melampsora lini closely attached to each other, on Linum usitatissimum | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Division: | Basidiomycota |
| Class: | Pucciniomycetes |
| Order: | Pucciniales |
| Family: | Melampsoraceae |
| Genus: | Melampsora |
| Species: | M. lini |
| Binomial name | |
| Melampsora lini | |
| Synonyms | |
Melampsora lini is a species of fungus and plant pathogen found in Ireland and commonly known as flax rust. [1]
The pathogen is an obligate biotroph meaning that each stage of its cycle is dependent on having a living host. The direction between reproducing sexually or asexually is dependent on the availability of a host.
Sexually, the life cycle starts when basidiospores land on flax leaves and form pycnium during December and through January. [2] Aecium are then formed from the pycnium after being fertilized with a pycniospore that is of a different mating type. Urediniospores and aeciospores then form pustules on the leaves that release more spores leading to further infection on neighboring leaves. Teliospores are then formed on the plants stem and undergo meiosis. Afterward, the teliospores shed haploid basidiospores repeating the cycle.
Asexually, the pathogen cycles between forming pustules and infecting surrounding leaves and plants. The pathogen is autoecious, meaning it completes its life cycle on a single plant. This is done purely through mitosis and produces genetically identical cells within the pustules. [3]
Radiola linoides has been recorded as a host for Melampsora lini in the UK. [4]
The pathogen prefers an environment in the temperate plains or hills of the United Kingdom rather than in high altitude and cold conditions. Due to this, there is a higher prevalence of resistance seen in hosts in these more favorable environment compared to hosts seen in mountainous ranges. [5] This is primarily due to the fact that there is a higher evolutionary pressure placed on these plants. Those that can defend against the pathogen go on to reproduce and pass on the genes responsible for their immunity.
Signs and symptoms of flax rust include: [6]
All signs are uniform for the hosts of the pathogen stated before. The only difference is the amount of signs seen due to the varying leaf shapes of the plants.
Symptoms are uniform for the hosts of the stated above. There is some variation in the amount of symptoms seen because of the amount of available host area infected by the pathogen.
The pathogen itself is not known for being detrimental to farmers since it does not take away from the total yield. During the 1990s, the pathogen was used as a role model for the molecular basis of plant immunity. The majority of research worked on observing the pathogenicity of a variety of physiological races of the pathogen and the resistance and susceptibility of the "gene-for-gene" relationship and understanding the breakdown of resistance when using a single gene. [1] This led to the use of incorporating multiple resistance genes to ensure resistance persisted.
From the late 1980s to present, the focus of research shifted to more specific molecular studies. One major discovery included the cytoplasmic nucleotide-binding leucine-rich repeat proteins. These proteins help provide resistance against fungi, oomycetes, bacteria, viruses, nematodes, insects, and parasitic plants. This was found through observing point mutations, re-assortment of mutation, and duplication and deletion of LRR units done by intragenic recombination in Australia in 2007. [3] [1]
Basidiomycota is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Basidiomycota includes these groups: agarics, puffballs, stinkhorns, bracket fungi, other polypores, jelly fungi, boletes, chanterelles, earth stars, smuts, bunts, rusts, mirror yeasts, and Cryptococcus, the human pathogenic yeast.
Rusts are fungal plant pathogens of the order Pucciniales causing plant fungal diseases.
Wheat leaf rust is a fungal disease that affects wheat, barley, rye stems, leaves and grains. In temperate zones it is destructive on winter wheat because the pathogen overwinters. Infections can lead up to 20% yield loss. The pathogen is a Puccinia rust fungus. It is the most prevalent of all the wheat rust diseases, occurring in most wheat-growing regions. It causes serious epidemics in North America, Mexico and South America and is a devastating seasonal disease in India. P. triticina is heteroecious, requiring two distinct hosts.
The gene-for-gene relationship is a concept in plant pathology that plants and their diseases each have single genes that interact with each other during an infection. It was proposed by Harold Henry Flor who was working with rust (Melampsora lini) of flax (Linum usitatissimum). Flor showed that the inheritance of both resistance in the host and parasite ability to cause disease is controlled by pairs of matching genes. One is a plant gene called the resistance (R) gene. The other is a parasite gene called the avirulence (Avr) gene. Plants producing a specific R gene product are resistant towards a pathogen that produces the corresponding Avr gene product. Gene-for-gene relationships are a widespread and very important aspect of plant disease resistance. Another example can be seen with Lactuca serriola versus Bremia lactucae.
This is a glossary of some of the terms used in phytopathology.
Gymnosporangium globosum is a fungal plant pathogen that causes cedar-hawthorn rust.
Phragmidium violaceum is a plant pathogen native to Europe, Africa, and the Middle East. It primarily infects Rubus species.
Puccinia schedonnardii is a basidiomycete fungus that affects cotton. More commonly known as a “rust,” this pathogen typically affects cotton leaves, which can decrease the quality of the boll at time of harvest. As large percentages of cotton in the United States are resistant to various rust varieties, there is little economic importance to this disease. In places where rust is prevalent, however, growers could see up to a 50% reduction in yield due to rust infection.
Puccinia asparagi is the causative agent of asparagus rust. It is an autoecious fungus, meaning that all stages of its life cycle – pycniospores, aeciospores, and teliospores – all develop upon the same host plant . Rust diseases are among the most destructive plant diseases, known to cause famine following destruction of grains, vegetables, and legumes. Asparagus rust occurs wherever the plant is grown and attacks asparagus plants during and after the cutting season. Asparagus spears are usually harvested before extensive rust symptoms appear. Symptoms are first noticeable on the growing shoots in early summer as light green, oval lesions, followed by tan blister spots and black, protruding blisters later in the season. The lesions are symptoms of Puccinia asparagi during early spring, mid-summer and later summer to fall, respectively. Severe rust infections stunt or kill young asparagus shoots, causing foliage to fall prematurely, and reduce the ability of the plant to store food reserves. The Puccinia asparagi fungus accomplishes this by rust lowering the amounts of root storage metabolites. The infected plant has reduced plant vigor and yield, often leading to death in severe cases. Most rust diseases have several stages, some of which may occur on different hosts; however, in asparagus rust all the life stages occur on asparagus. Because of this, many observers mistake the different stages of the Puccinia asparagi life cycle as the presence of different diseases. The effects of Puccinia asparagi are present worldwide wherever asparagus is being grown. Asparagus rust is a serious threat to the asparagus industry.
Puccinia helianthi is a macrocyclic and autoecious fungal plant pathogen that causes rust on sunflower. It is also known as "common rust" and "red rust" of sunflower.
Puccinia menthae is a fungal plant pathogen that causes rust on mint plants. It was originally found on the leaves of Mentha aquatica.
Uromyces viciae-fabae var. viciae-fabae is a plant pathogen commonly known as faba-bean rust. The rust is distinguished by the typical rust-like marks on the stem and leaves, causing defoliation and loss of photosynthetic surface along with reduction in yield. The disease is fungal and is autoecious meaning it has one plant host. The rust of faba beans is macrocyclic, or contains 5 spores during its life cycle.
Melampsora medusae is a fungal pathogen, causing a disease of woody plants. The infected trees' leaves turn yellowish-orange. The disease affects mostly conifers, e.g. the Douglas-fir, western larch, tamarack, ponderosa, and lodgepole pine trees, but also some broadleaves, e.g. trembling aspen and poplars. Coniferous hosts are affected in late spring through early August, and trembling aspens and poplars from early summer to late fall. It is one of only two foliage rusts that occur naturally in British Columbia.
Sporisorium reilianum Langdon & Full., (1978), previously known as Sphacelotheca reiliana, and Sporisorium reilianum, is a species of biotrophic fungus in the family Ustilaginaceae. It is a plant pathogen that infects maize and sorghum.
Phakopsora pachyrhizi is a plant pathogen. It causes Asian soybean rust.
Austropuccinia is a monotypic genus of rust native to South America with the only species Austropuccinia psidii, commonly known as myrtle rust, guava rust, or ʻōhiʻa rust. It affects plants in the family Myrtaceae. It is a member of the fungal complex called the guava rust group. The spores have a distinctive yellow to orange colour, occasionally encircled by a purple ring. They are found on lesions on new growth including shoots, leaves, buds and fruits. Leaves become twisted and may die. Infections in highly susceptible species may result in the death of the host plant.
Phakopsora euvitis is a rust fungus that causes disease of grape leaves. This rust fungus has been seen in regions including: Eastern Asia, Southern Asia, Southwestern Brazil, the Americas, and northern Australia. It is widely distributed in eastern and southern Asia but was first discovered on grapevines in Darwin, Australia in 2001 and was identified as Asian grapevine leaf rust by July 2007.
Melampsora amygdalinae is a fungal pathogen and part of the division Basidiomycota. It is known as a rust fungus that is host specific. M. amygdalinae commonly infects willows of the genus Salix. This fungus was first discovered in 1909 by Heinrich Klebahn who was a professor of soil biology in Hamburg. Neimi at el. explain how the pathogen occurs throughout the whole distribution of the host, and the small natural populations are an area of interest. This rust fungus is annual and autoecious, which references the fungus spending its entire life in a single host.
The study of gene-for-gene interactions uncovers genetic components, evolutionary impacts, and ecological/economic implications between rust fungi and plants. Rust fungi utilize the gene-for-gene interaction to invade host plants. Conversely, host plants utilize the gene-for-gene interaction to prevent invasion of rust fungi.
Puccinia sorghi, or common rust of maize, is a species of rust fungus that infects corn and species from the plant genus Oxalis.