Heterosis and Hybrid Vigor: Meaning, Properties, Procedure and Genetic basis of Heterosis/ Hybrid Vigor and its Advantages

INTRODUCTION:

Hybrids are the resultants of the cross between two parents.

The hybrids can be produced via plant breeders manually by just crossing between selected parents. Cross between selected parents produces F1 Hybrids that were further self-crossed to produce pure lines that can be used as pure-line cultivars for autogamous plant species or as parents to produce hybrids for allogamous crop species.

What are Hybrids/ Heterosis/ Hybrid Vigor

Hybrids are superior to the parents and this ability of hybrids to have superiority than parents is also known as Hybrid Vigor or Heterosis.

Properties of Hybrid/ Heterosis/ Hybrid Vigor

Hybrids have important role in plant improvement.

They are used to develop pure lines for cross pollinating plants.

Hybrids are associated with greater productivity and vigor, but this varies among various crop species.

The frequency of hybrids is more in allogamous plants and less in autogamous plants.

Mechanism to develop Hybrids:

1.ISOLATION OF PURELINES

2.EVALUATION OF PURELINES (To determine superior performance)

Genetic basis of Hybrid vigor/ Heterosis

Genetic explanations of hybrid vigor have included additivity of favorable alleles with partial to complete dominance effects and nonadditive effects due to overdominance and epistatic effects.

But it is difficult to find out the exact gene effect.

Hybrid vigor is dependent on two factors: differences in gene frequencies between the two parents and some level of dominance among the parents.

QUESTION PRACTICE

Which of the following can result heterosis? (ICAR PG Plant biotechnology 2022)

Dominance

Over Dominance

Epistasis

 More than one answer are correct