Explain the methods of breeding for disease resistance.

(N/A) Breeding for disease resistance is carried out using conventional breeding techniques or mutation breeding.
The conventional method involves hybridization and selection. Its steps are essentially identical to those used for breeding for other agronomic traits like high yield.
The sequential steps are:
$1$. Screening germplasm for resistance sources.
$2$. Hybridization of selected parents.
$3$. Selection and evaluation of the hybrids.
$4$. Testing and release of new varieties.
Some crop varieties developed through these methods are:

Crop	Variety	Resistance to diseases
Wheat	Himgiri	Leaf and stripe rust,hill bunt
Brassica	Pusa Swarnim (Karan rai)	White rust
Cauliflower	Pusa Shubhra,Pusa Snowball $K-1$	Black rot and Curl blight black rot
Cowpea	Pusa Komal	Bacterial blight
Chilli	Pusa Sadabahar	Chilli mosaic virus,Tobacco mosaic virus and Leaf curl

Conventional breeding is often constrained by the limited availability of disease resistance genes in crop varieties or wild relatives.
Mutation breeding involves inducing mutations in plants through various means (e.g.,radiation or chemicals) and screening for resistance. This can help identify desirable genes.
Other methods include selection among somaclonal variants and genetic engineering.