Negative Interaction between Plants and Microbes

Negative Interaction between Plants and Microbes

	Negative Interaction Between Plants And Microbes As already discussed, parasitism is the only negative interaction between the plants and microbes. As parasites, the microbes, like bacteria, fungi, viruses and algae, cause infections in the host plant leading the development of disease and loss of commercial value in case the host plant is an agricultural crop.
To cause the disease, the parasite must accomplish two important things: 1. It must enter the host plant. 2. It must establish itself at the specific target site within the plant. After accomplishing this, the parasite is able to overcome the plant defence mechanisms and causes the disease.
There are different portals of entry for each microbe. Thus bacteria and viruses enter the host tissue through the natural openings like stomata, lenticels, etc. Fungi have a separate mode of entry. Either the fungal spore enters directly through the natural openings and germinates within the host tissue, or the spore on falling on the plant surface, forms a special adaptation called appresorium which anchors the spore onto the substratum.
From the appresorium arises a small projection called the infection peg which has a sharp tip through which it penetrates the host cell wall actively The pathogens can also enter through open wounds (scratches) on the plant surfaces. Once the pathogen enters the host tissue, it tries to overcome the host defence mechanisms (production of phytoalexins on induction by the elicitors which are the pathogens themselves) and establishes relationship with the host. This interaction is of two kinds. One is biotrophic interaction.
	Here the pathogen enters into a harmonious relationship with the host with the pretext that it continues to obtain nutrition from the plant for a long time. Thus it does not kill the plant instantaneously. Another relationship is the necrotrophic wherein the pathogen on entering the host kills the host and obtains the nutrition from the dead tissues. After the disease is established and even during the course of the disease establishment, a series of symptoms can be visualised on the host surface which is an indication of disease onset

Some examples of parasites on plants are:

Bacteria¾Enwinia carotovora causing soft rot in carrots; Xanthomonas campestris pv oryzae causing bacterial blight in rice.

Fungus-Fusarium oxysporum causing wilt disease in many plants (cotton, banana).

Virus-Tobacco mosaic virus causing mosaic disease in tobacco

Phyllosphere
Characteristic Features of Phyllosphere Microflora
Positive Interactions of Plants and Microbes
Leaf Nodule
Mycorrhiza
Types of Mycorrhizae
Vam Fungi
Negative Interaction between Plants and Microbes
Animal-Microbe Interactions
Predation of Microbes by Animals
Interaction between Microbes and the Gut
Interaction between Microbes and the Rumen
Insect-Microbe Symbiosis
Fungal-Scale Insect Associations
Interaction between Termites and Microbes
Termite Gut Microbes
Synthesis of Metabolites

Home | Site map | Submit Article | Directory | Search