Plant Breeding for Disease Resistance:

Resistance is defined as the genetic ability of a plant to prevent pathogen from causing disease.

Many types of diseases can be cured by virus, bacteria and fungi:

Pathogen	Disease caused by them
Fungi	Brown rust of wheat, late blight of potato, red rot of sugarcane
Bacteria	Blight of rice, black rot of crucifer
Virus	Tobacco mosaic, turnip mosaic

There are two methods for making disease resistant crops:

1) Conventional breeding methods: It follows under given procedure:

1. Selection of germ-plasm for disease resistance. 
2. Hybridization of selected plants. 
3. Selection and evaluation of hybrids.
4. Testing and release of new hybrids in the market.

Some varieties of crops developed by this method:

Crops	Variety	Resistance to disease
Wheat	Himgiri	Leaf and stripe rust, hill bunt
Brassica	Pusa Swarnim (Karan rai)	White rust
Couliflower	Pusa Shubra, Pusa Snowball K-1	Black rot, curl blight
Cowpea	Pusa Komal	Bacterial blight
Chilli	Pusa Sadabahar	Chilly mosaic virus, tobacco mosaic virus, leaf curl

2) Mutation breeding:

Mutation is a phenomenon by which genetic variations are achieved through changes in base sequence which creates new characters absent in parental generations. It can achieved by introducing chemicals like aniline or radiations like gamma rays. It follows under given procedure:

1. Introduction of mutation in selected plants.
2. Then testing the resistance gained by it.
3. Selection of desired plant for breeding and manipulation.

Some varieties of crops developed by this method:

Crops	Variety developed	Resistance to disease
Moong bean	Moong bean	Yellow mosaic virus and powdery mildew
Bhindi(Abelmoschus esculentus)	Parbhani Kranti	Yellow mosaic virus