Hairy Roots Characteristics Analysis

The question asks about the defining features of 'hairy roots' induced by Agrobacterium rhizogenes in vitro.

• P. High degree of lateral branching: Agrobacterium rhizogenes infection leads to significant hyperplasy and hypertrophy, resulting in profuse lateral root formation. This is a hallmark characteristic of hairy roots.
• Q. Genetic instability of culture: Hairy roots are a result of the integration of the Ri plasmid T-DNA into the plant genome. This transformation process can lead to genetic alterations and instability within the cultured cells over time.
• R. Absence of geotropism: While hairy roots can sometimes exhibit abnormal growth patterns, they generally retain their ability to respond to gravity (geotropism), although the response might be modified. A complete absence of geotropism is not a primary characteristic.
• S. Poor biomass production: Hairy roots often exhibit rapid growth and high proliferation rates due to hormonal independence, potentially leading to significant biomass accumulation, especially when optimized for secondary metabolite production. Therefore, 'poor' biomass production is not accurate.

Identifying Correct Characteristics

Based on the analysis, characteristics P (high degree of lateral branching) and Q (genetic instability of culture) accurately describe hairy roots induced by Agrobacterium rhizogenes.

Therefore, the correct option includes P and Q.

Conclusion

The combination P and Q represents the key characteristics of hairy roots induced by Agrobacterium rhizogenes.