Vitamins in Plants | Plant Biochemistry

10.1 Learning Objectives

Understand the role of vitamins in plants.
Differentiate between water-soluble and fat-soluble vitamins.
Explain vitamin biosynthesis in plants.
Describe biochemical roles and deficiency symptoms of vitamins.

10.2 Introduction to Plant Vitamins

Vitamins are essential organic compounds required for plant growth and metabolism. Unlike animals, plants synthesize their own vitamins. Vitamins function as coenzymes, antioxidants, and regulatory molecules in plant physiological processes.

Key idea: Vitamins do not directly provide energy but enable enzymes to function efficiently.

10.3 Classification of Vitamins

1) Water-Soluble Vitamins

Vitamin C (Ascorbic acid)
B-complex vitamins (B1, B2, B6, B12, etc.)

2) Fat-Soluble Vitamins

Vitamin A (Carotenoids)
Vitamin D
Vitamin E
Vitamin K

Water-soluble vitamins dissolve in water and are not stored in large amounts, while fat-soluble vitamins are stored in plant tissues.

10.4 Water-Soluble Vitamins and Their Functions

Vitamin	Function in Plants
Vitamin C (Ascorbic acid)	Antioxidant, stress tolerance, photosynthesis
Vitamin B1 (Thiamine)	Carbohydrate metabolism
Vitamin B2 (Riboflavin)	Energy production
Vitamin B6 (Pyridoxine)	Amino acid metabolism

10.5 Fat-Soluble Vitamins and Their Functions

Vitamin	Function in Plants
Vitamin A (Carotenoids)	Pigment synthesis, photoprotection
Vitamin D	Regulation of calcium-related processes
Vitamin E	Antioxidant, membrane protection
Vitamin K	Photosynthesis and electron transport

10.6 Vitamin Synthesis in Plants

Vitamin C is synthesized via the Smirnoff–Wheeler pathway.
Carotenoids (Vitamin A) are synthesized in plastids.
Many vitamins are produced through metabolic pathways such as glycolysis and the TCA cycle.

10.7 Biochemical Roles of Vitamins

Enzyme activation and cofactor functions
Antioxidant defense against oxidative stress
Photosynthesis and light stress regulation
Plant growth, development, and defense mechanisms

10.8 Deficiency Symptoms in Plants

Vitamin	Deficiency Effects
Vitamin C	Reduced stress tolerance
Vitamin B	Growth inhibition, chlorosis
Vitamin A	Poor pigmentation, reduced photosynthesis
Vitamin K	Disruption of photosynthesis

10.9 Sources of Vitamins in Plants

Synthesized within plant cells
Derived from metabolic pathways
Influenced by soil microorganisms

Self-Assessment Questions

What are the two main categories of plant vitamins?
Name one water-soluble and one fat-soluble vitamin.
Explain the role of Vitamin C in plants.
How do plants synthesize Vitamin A?
Describe one effect of Vitamin B deficiency in plants.

Chapter 10: Vitamins in Plants