A brief description on enzymatic activity in Seed germination.

1. Enzymatic Activities During
Seed Germination
Amit
2022BT01M
M.Sc Agricultural Biotechnology
CCS HAU,Hisar

2. Introduction
•Enzymatic activity during seed germination is a critical
process that involves the activation of various enzymes
to break down stored nutrients and enable the embryo to
grow into a seedling.
•This process is essential for the successful transition
from a dormant seed to an actively growing plant.
•Enzymatic activity is important during germination
because the hydrolysis of compounds that provide
energy to the plant for growth needs to occur.
•There are some key enzymes and their roles during
seed germination.

3. •During seed germination, the
scutellum and the aleurone layer
are responsible for the
production of hydrolytic
enzymes.
•These enzymes allow for the
mobilization of storage material
of the endosperm, which helps
to support the early growth of
seedlings.
•Once the process is completed,
scutellum and aleurone layer
cells undergo programmed cell
death and their content is used to
support the growth of the
germinated embryo.

5. Some key enzymes and their
roles during seed germination
• Amylase
• Proteases
• Lipases
• Cellulase
• Gibberellin-induced enzymes
• Phosphatases
• Respiration-related enzymes.

6. Amylase
•Amylase enzymes are responsible for the
hydrolysis of starch stored in the seed endosperm
into soluble sugars, primarily maltose. This
provides energy to the emerging seedling, reqiure
for initial growth.
•It is produced during germination to mobilize
storage macromolecules in the endosperm because
simpler molecules are needed to provide energy to
the seed during germination.

7. Proteases
•Proteases, also known as proteolytic enzymes, break
down stored proteins into amino acids. These amino
acids are essential for the synthesis of new proteins
required for the growth and development of the
seedling.
•Nutrient Mobilization- The stored proteins are in
an insoluble form and cannot be directly utilized by
the developing embryo. Proteases are responsible for
breaking down these stored proteins into amino acids
or smaller peptides that can be transported to the
growing embryo

8. •Defense Mechanism: Proteases also act as a defense
mechanism against pathogens and pests. They can break
down proteins in invading microorganisms, limiting
their growth and stop to spread within the seed.
•Activation of Other Enzymes- Proteases can activate
other enzymes involved in seed germination. For
instance, they can cleave inactive enzyme precursors
(zymogens or proenzymes) into their active forms.

9. Lipases
• Lipase enzymes hydrolyze stored lipids (fats and oils)
into glycerol and fatty acids.E.g. triglyceride hydrolase is
the main lipase to start the mobilization of the stored
lipids.
• It is responsible for catalyzing the hydrolysis of ester
linkages in mono, di and triacylglycerides to produce free
fatty acids and glycerol.
•Role of lipase during seed germination-
• Energy source for the developing seedling.
• Supporting Lipid Metabolism-maintaining lipid
homeostasis within the seedling.

10. Cellulase
•Cellulase enzymes help in breaking down
cellulose, a complex polysaccharide found in
plant cell walls.
•This enzyme activity becomes crucial as the
seedling starts to elongate and penetrate the soil,
requiring the softening of cell walls for root and
shoot growth by break down the cellulose fibers
in the cell walls.

11. Gibberellin-induced enzymes
•Here's an explanation of the role of Gibberellin-
induced enzymes, focusing on their involvement in
seed germination-
•Seed Dormancy Breaking- by stimulating the
production of specific enzymes, α-Amylase is
responsible for the hydrolysis of starch stored in the
seed into simpler sugars like maltose.
•Cell Wall Softening
•Promoting stem elongation

12. Phosphatases
•Phosphatase enzymes are involved in releasing
inorganic phosphate from organic compounds within the
seed. This released phosphate is essential for various
metabolic processes and energy transfer.
•Phosphatases play a significant role in seed
germination by facilitating the mobilization of stored
phosphate reserves in seeds.
•In seeds, phosphate is often stored in the form of phytic
acid or phytate, which are not directly accessible to the
developing embryo.
•Energy Production -The phosphate released from
phytic acid by phosphatases contributes to ATP
production.

13. Respiration-related
enzymes
•Respiration-related enzymes play a vital role in seed
germination by facilitating the process of cellular
respiration, which is the metabolic pathway
responsible for producing energy from stored
nutrients in the seed.
•Respiration-related enzymes are crucial for seed
germination because they facilitate the breakdown of
stored nutrients, such as carbohydrates, and convert
them into ATP, the primary energy source for the
developing seedling.

14. Other enzymes
•β-glucanases- It take part in metabolic reactions
of germination and represent a group of
carbohydrase enzymes that breakdown glycosidic
bonds in β-glucans
•Xylanases- Xylanases are glycoproteins of one
chain whose molecular weight ranges between 6
and 80 kDa.
It is required for the controlled remodelling of
the plant cell wall during growth and
development.