Magnesium deficiency in plants leads to chlorosis in leaves.

Explanation

### Step-by-Step Solution:

1. **Understanding Chlorosis**:
- Chlorosis is defined as the yellowing of leaves due to the loss of chlorophyll, the green pigment essential for photosynthesis.

2. **Role of Magnesium in Plants**:
- Magnesium is a crucial component of chlorophyll. It plays a vital role in the photosynthesis process by helping in the formation of chlorophyll molecules.

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