6. In plant lateral root initiates from
   (1) Pericycle (2) Cortex
   (3) Pith (4) Endodermisv

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Introduction

Lateral roots are essential for increasing the root system’s surface area, allowing plants to efficiently absorb water and nutrients from the soil. The formation of lateral roots begins internally within the parent root, specifically from the pericycle, a layer of cells surrounding the vascular tissue. Understanding this origin is fundamental in plant developmental biology.

Pericycle: The Site of Lateral Root Initiation

• The pericycle is a layer of parenchyma cells located just inside the endodermis and directly surrounding the vascular cylinder (stele) in roots.

• It maintains meristematic potential, meaning these cells can re-enter the cell cycle and divide to give rise to new organs such as lateral roots.

• Lateral root primordia form through pericycle cells undergoing asymmetric divisions, eventually producing a new root that grows outward, penetrating the cortex and epidermis.

Hormonal Control and Developmental Regulation

• Auxin plays a crucial role in stimulating pericycle cells for lateral root formation by regulating gene expression and cell cycle progression.

• Specific molecular signals and environmental cues finely tune the spatiotemporal patterning of lateral root emergence to optimize nutrient acquisition and stability.

Comparative Origin in Plants

• In higher plants like angiosperms and gymnosperms, the pericycle is the common source of lateral roots.

• In some lower vascular plants, lateral roots may originate from the endodermis, but this is less common in advanced plants.

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Summary Table: Lateral Root Origin and Characteristics

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Conclusion

Lateral roots initiate from the pericycle in plant roots, where specialized cells regain their meristematic capability to form root primordia. This process is tightly regulated by hormonal and environmental factors, enabling plants to adapt their root architecture for improved growth and resource acquisition.