Q.(a) List out the new breeding techniques involved in developing new traits in plant breeding. OR

(a) New plant-breeding techniques include mutation, polyploidy, wide hybridisation, marker-assisted selection, genetic engineering and genome editing; (b) rice is a staple food crop and teak a premium durable timber.

(a) New Breeding Techniques for Developing New Traits

Modern plant breeding uses several advanced techniques beyond classical hybridisation and selection to develop new and improved traits:

1. Mutation breeding: inducing mutations using physical mutagens (e.g., gamma rays, X-rays) or chemical mutagens (e.g., EMS, colchicine) to generate novel genetic variation for selection.
2. Polyploidy breeding: doubling the chromosome number, often using colchicine, to produce polyploid varieties, which frequently show larger organs and greater vigour.
3. Wide hybridisation with embryo rescue: crossing distantly related species or genera, and rescuing the resulting hybrid embryo (which would otherwise abort) by growing it in tissue culture.
4. Marker-assisted selection (MAS): using DNA markers closely linked to desirable traits to identify and select superior plants more quickly and accurately than by phenotype alone.
5. Genetic engineering/transgenic technology: direct transfer and insertion of a specific desirable gene, often from an unrelated organism, e.g., Bt cotton, Golden Rice.
6. Genome editing: precise, targeted modification of specific genes using tools such as CRISPR-Cas9.
7. Exploiting somaclonal variation: utilising the genetic variability that arises spontaneously among plants regenerated through tissue culture, as a source of new traits.

(b) Economic Importance of Rice and Teak

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