36. Mutation in a gene x in Arabidopsis thaliana results in more number of lateral root formation. Which one of the following is the correct statement?
(1) The gene product acts as a positive factor of lateral root formation.
(2) The gene product acts as a negative regulator of lateral root formation.
(3) The gene product is not likely to be involved in lateral root formation.
(4) The gene product promotes replication for lateral root development
The correct statement is:
(2) The gene product acts as a negative regulator of lateral root formation.
Explanation:
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A mutation causing an increase in the number of lateral roots suggests that the normal gene product functions to inhibit or restrict lateral root formation.
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Thus, the gene product likely acts as a negative regulator, preventing excessive lateral root initiation and maintaining controlled root architecture.
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Several known genes in Arabidopsis, such as certain Aux/IAA proteins, act as repressors in auxin signaling pathways that regulate lateral root formation; mutations in these lead to increased lateral root numbers.
Introduction
Lateral root formation is a vital aspect of root system architecture in plants, influencing resource uptake and stability. In Arabidopsis, gene regulation tightly controls initiation and development of lateral roots. Mutations that increase lateral root numbers often reveal the role of negative regulatory genes essential for balanced root branching.
Role of Negative Regulators in Lateral Root Formation
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Genes encoding Aux/IAA transcriptional repressors suppress auxin-responsive gene expression required for lateral root initiation and growth.
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Loss-of-function or dominant-negative mutations in these genes disrupt repression, resulting in hyperproliferation of lateral roots.
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Regulatory pathways involving other transcription factors (ARF7/ARF19) and LBD family genes also mediate lateral root patterning and are influenced by Aux/IAA regulators.
Implications of Increased Lateral Roots
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Excess lateral roots may affect overall plant resource allocation and soil interaction, indicating the importance of fine-tuned genetic control.
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Understanding these regulatory genes offers potential in agricultural engineering for optimized root systems to enhance nutrient acquisition and stress resistance.
Summary Table: Gene Functions in Lateral Root Formation
| Mutation Effect | Gene Product Role |
|---|---|
| Increase in lateral root number | Negative regulator of LR formation |
| Reduction or absence of lateral roots | Positive regulator or essential factor |
Conclusion
A gene mutation in Arabidopsis causing increased lateral root formation indicates that the gene product normally acts as a negative regulator. This mechanism prevents uncontrolled branching ensuring balanced root development.
2 Comments
Kajal
November 13, 2025Option 2 the normal gene product act as negative regulator of lateral root
Kavita Choudhary
November 21, 2025A gene mutation in Arabidopsis causing increased lateral root formation that indicates that gene product normally acts as negative regulator. This mechanism prevents un controlled brached ensuring balance root development