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Thursday, March 1, 2007

Agrobacterium Mediated Gene Transfer: Applications

Agrobacterium are gram –ve bacteria of family Rhibiaceae.they are often found in rhizosphere region of plants and are pathogenic. Their phytogenetic activity is listed below

Agrobacterium tumifaciance: Induces Crown gall disease
Agrobacterium rhizogens: Induce hairy root disease

The pathogenic activity agrobacterium species are acquired due to the presence of certain very large plasmids known as Ti (Tumour inducing) and R i(Root inducing)  plasmids.

Ti Plasmid - Image Source

A.tumifaciance is characterized by uncontrolled proliferation of cells causing tumours.These plasmids have specific regions for producing phytohormones and special amino acid [Opines] synthesizing region, which form the carbon source.

The plasmids gets incorporated into the plant genome during infection and which inturn  results in causing disease in plant.

It is the first identified successful gene transformation applicable for plants. It is considered as “nature’s most efficient plant genetic engineer”.

Application of Agrobacterium in Genetic Engineering

These plasmids are very useful in transferring gene into the plant genome, so desired gene can be cloned into these plasmids and transferred. virulence region can be removed and can be successfully used in gene transfer.

Mushroom Cultivation

Mushroom Cultivation: A Process which can be done at home

Mushrooms are simple achlorophyllous (non green) plants. Mushrooms suddenly appear on logs, termite mounts and grasslands during monsoon and lives only for a few days. These ephemeral organisms include edible, non-edible, medicinal and poisonous species. Edible species are excellent and have been used as food from pre-historic times. But poisonous species, if accidentally consumed, results in toxicity which may become fatal. Cultivation of edible species for consumption is the only solution to avoid such accidents.

Types of Mushrooms

Fifty thousand species of mushrooms have been discovered. Among them, 20.000 are edible, 20 have been cultivated and 6 have been produced on commercial scale. These are

  1. Button mushroom, 
  2. Oyster mushroom,
  3. Paddy straw mushroom,
  4. Shiitake mushroom,
  5. Ear mushroom and
  6. Milky mushrooms.

Among these, button, oyster, paddy straw and milky are cultivated in India.

mushroom cultivation process

As far as the flavour is concerned, button mushroom is the most relished. But its cultivation is limited to cooler regions of the world. In south India, it is cultivated in Ooty. Cultivation of this species in other regions needs control of climate. For example, air conditioners are required to lower the temperature in culture rooms. Therefore, in places like Kerala, this species is not cultivated. Instead, high temperature tolerant species like Calocybe and Pleurutus are suitable.
Need for Mushroom Cultivation

Recently there is added interest in mushrooms for many reasons. It is the only crop that can be harvested in 2-3 weeks. Its flavour is unique and nutritional qualities are superior to vegetables. Its protein is complete and calorie is low. Many species have medicinal properties. Some have anti- tumour activity, some are anti-aging and some have hypo-lipidemic action. Production technology is simple and requires lesser input than other industries. Demand for mushroom is increasing the world over and supply is small. It is a growing industry and there is potential for employment generation. Another advantage for mushroom cultivation is its utility in agro-industrial waste processing. Thus, it is a useful technology for waste management also.

Courtesy: Dr.P.Balakrishnan