Endo-[beta]-Mannanase Activity from Individual Tomato Endosperm Caps and Radicle Tips in Relation to Germination...

Area of Science:

• Plant Biology
• Seed Physiology
• Biochemistry

Background:

• Endo-beta-mannanase is a key enzyme in endosperm weakening.
• Endosperm weakening is crucial for radicle emergence in tomato seeds.

Purpose of the Study:

• To investigate the role of endo-beta-mannanase in tomato seed germination.
• To determine if mannanase activity is the rate-limiting factor for radicle emergence.

Main Methods:

• Utilized a sensitive, single-seed assay to measure mannanase activity.
• Analyzed mannanase activity diffusing from excised tomato endosperm caps.
• Applied osmoticum and abscisic acid to alter germination rates.

Main Results:

• Observed a 100- to 10,000-fold range of mannanase activity among individual tomato seeds.
• Found that osmoticum and abscisic acid did not inhibit initial mannanase activity.
• Identified a bimodal distribution of activity in dormant seed lots, with low activity linked to dormancy.

Conclusions:

• Endo-beta-mannanase activity in the endosperm cap is linked to radicle emergence.
• Mannanase activity is not the sole or limiting factor for germination under all conditions.
• Seed dormancy influences mannanase activity levels.