Question

Write short notes on, (i) Embryo rescue, (ii) lnbreds through another culture, (iii) Somatic hybrids, (iv) Protoplast fusion., (v) Culture media, (vi) Haploids (Androgenic plants), (vii) Mass selection, (viii) Hybrid vigour, (ix) Hybridization, (x) Somaclonal variation, (xi) Biofortification.

Answer 1

(i) Embryo rescue: Embryo rescue is one of the successful forms of in-vitro culture techniques that is used to recover dormant embryos, immature embryos into a new plant. This technique plays an important role in fruit crops, early-maturing seeds, triploid plants as well as obtaining distant hybrids preventing embryo degeneration at early development stages and shortening breed cycle.

(ii) Inbreds through anther culture: Plants with inbreeding depression are called Inbreds. They are not fit to produce seeds. By means of anther culture, these plants made into fertilie plants.

(iii) Somatic hybrids: Plants obtained through somatic hybridization are called somatic hybrids. Its major contribution to plant breeding is in overcoming common crossing barriers among plant species and in organelle genetics and breeding.

(iv) Protoplast fusion: Protoplast fusion is a physical phenomenon. During fusion, two or more protoplasts come in contact and adhere with one another either spontaneously or in presence of fusion induc­ing chemicals.

(v) Culture media: A solid, liquid or semi-solid substratum provide to support the growth of microorganisms and also supply nutrients to the microbes is called Culture medium or Nutrient medium. The most commonly used culture medium is MS medium. Different types of media are used for growing different types of cells.

(vi) Haploids (Androgenic plants): Plants obtained by pollen culture are called Haploid plants or androgenic plants. These plants contain single set of chromosomes. These are used to identify the lethal mutations, produce homozygous plants, etc.

(vii) Mass selection: Mass selection is the simplest method used in which larger number of cross pollinated plants based on phenotype. Selection of seeds of these plants are harvested and mixed to result in a new form or a new variety.

(viii) Hybrid vigour: Heterosis, hybrid vigor, or outbreeding enhancement, is the improved or increased function of any biological quality in a hybrid offspring. An offspring is heterotic if its traits are enhanced as a result of mixing the genetic contributions of its parents.

(ix) Hybridization: Hybridization is the process of interbreeding between individuals of different species (interspecific hybridization) or genetically divergent individuals from the same species (intraspecific hybridization). Offspring produced by hybridization may be fertile, partially fertile, or sterile.

(x) Somaclonal variation: Somaclonal variation is the variation seen in plants that have been produced by plant tissue culture. Chromosomal rearrangements are an important source of this variation.

(xi) Biofortification: Biofortification is the idea of breeding crops to increase their nutritional value. This can be done either through conventional selective breeding, or through genetic engineering.