''Melampsora lini'' is a species of
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 ...
found in Ireland and commonly known as flax rust.
Life cycle
The pathogen is an obligate
biotroph
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has c ...
meaning that each stage of its cycle is dependent on having a living
host
A host is a person responsible for guests at an event or for providing hospitality during it.
Host may also refer to:
Places
* Host, Pennsylvania, a village in Berks County
People
*Jim Host (born 1937), American businessman
* Michel 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
An aecium (plural aecia) is a specialised reproductive structure found in some plant pathogenic rust fungi that produce aeciospores. Aecia may also be referred to as "cluster cups". The term aecidium (plural aecidia) is used interchangeably but i ...
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
Stem or STEM may refer to:
Plant structures
* Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang
* Stipe (botany), a stalk to support some other structure
* Stipe (mycology), the stem of a mushro ...
and undergo
meiosis. Afterward, the teliospores shed
haploid
Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively ...
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
In cell biology, mitosis () is a part of the cell cycle in which replicated chromosomes are separated into two new nuclei. Cell division by mitosis gives rise to genetically identical cells in which the total number of chromosomes is mainta ...
and produces genetically identical cells within the pustules.
Hosts
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. 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. Textiles made from flax are known in ...
*
Linseed
*
Wheat
Symptoms and signs
Signs and symptoms of flax rust include:
Signs
* Light yellow to orange-yellow
sori
* Reddish-yellow to orange