''Melampsora lini'' is a species of
fungus
A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...
and
plant pathogen found in Ireland and commonly known as flax rust.
Life cycle
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.
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
pustule
A skin condition, also known as cutaneous condition, is any medical condition that affects the integumentary system—the organ system that encloses the body and includes skin, nails, and related muscle and glands. The major function of this ...
s on the leaves that release more spores leading to further infection on neighboring leaves.
Teliospore
Teliospore (sometimes called teleutospore) is the thick-walled resting spore of some fungi (Rust (fungus), rusts and Smut (fungus), smuts), from which the basidium arises.
Development
They develop in ''telium, telia'' (sing. ''telium'' or ''telio ...
s are then formed on the plants
stem and undergo
meiosis
Meiosis () is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, the sperm or egg cells. It involves two rounds of division that ultimately result in four cells, each with only one c ...
. Afterward, the teliospores shed
haploid
Ploidy () is the number of complete sets of chromosomes in a cell (biology), cell, and hence the number of possible alleles for Autosome, autosomal and Pseudoautosomal region, pseudoautosomal genes. Here ''sets of chromosomes'' refers to the num ...
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
Mitosis () is a part of the cell cycle in eukaryote, eukaryotic cells in which replicated chromosomes are separated into two new Cell nucleus, nuclei. Cell division by mitosis is an equational division which gives rise to genetically identic ...
and produces genetically identical cells within the pustules.
Hosts
''
Radiola linoides'' has been recorded as a host for ''Melampsora lini'' in the UK.
The pathogen prefers an environment in the temperate plains or hills of the
United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...
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. 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.
*
Flax
Flax, also known as common flax or linseed, is a flowering plant, ''Linum usitatissimum'', in the family Linaceae. It is cultivated as a food and fiber crop in regions of the world with temperate climates. In 2022, France produced 75% of t ...
*
Linseed
*
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 ...
Symptoms and signs
Signs and symptoms of flax rust include:
Signs
* Light yellow to orange-yellow
sori
* Reddish-yellow to orange
uredinia on leaves
* Brown to black
telia
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
* Yellowing of leaves
* Necrotic leaf spots
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.
Research
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.
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.
References
{{DEFAULTSORT:Melampsora Lini
Fungal plant pathogens and diseases
Pucciniales
Fungi described in 1818
Taxa named by Christian Gottfried Ehrenberg
Fungus species