Graft Union Formation: Step-by-Step

The successful integration of a scion onto a stock in plant grafting relies on a sequential development process known as graft union formation. Understanding these steps is key.

Sequence of Graft Union Stages

1. Step B: Parenchyma Production
   Initial response involves the production of parenchyma cells from the cambial regions at the wound surface of both scion and stock.
2. Step A: Cell Interlinking
   The produced parenchyma cells proliferate and divide, leading to the intermingling and interlinking of these cells, forming a callus mass that bridges the gap.
3. Step E: Cambium Differentiation
   Parenchyma cells within the callus subsequently undergo redifferentiation, resulting in the differentiation of parenchyma cells into new cambial cells.
4. Step D: Cambium Connectivity
   This process establishes a continuous vascular cambium layer, enabling the connectivity of the original cambium in both scion and stock through the newly formed tissue.
5. Step C: Vascular Tissue Development
   The established, continuous cambium then actively participates in the production of new vascular tissues (xylem and phloem), linking the vascular systems and completing the graft union.

Final Sequence Determination

The correct order of these essential steps is determined by their biological progression:

B (Parenchyma Production) → A (Cell Interlinking) → E (Cambium Differentiation) → D (Cambium Connectivity) → C (Vascular Tissue Development)

This sequence corresponds to the correct answer choice.