Pepper gene encoding a basic class II chitinase is inducible by pathogen and ethephon

Area of Science:

• Plant Pathology
• Molecular Biology
• Biochemistry

Background:

• Chitinases are enzymes involved in chitin degradation, playing roles in plant defense against pathogens.
• Plant chitinases are classified into different classes based on their structural features.

Purpose of the Study:

• To isolate and characterize a novel chitinase cDNA from pepper leaves.
• To investigate the expression patterns of the identified chitinase gene in response to pathogen infection and signaling molecules.

Main Methods:

• Isolation of chitinase cDNA (CAChi2) from pepper leaf cDNA library.
• Sequence analysis to determine chitinase class and evolutionary relationships.
• Southern blot analysis to assess gene copy number.
• RT-PCR to analyze gene expression under different treatments.

Main Results:

• A 1004-bp cDNA clone, CAChi2, encoding a basic class II chitinase was identified.
• CAChi2 lacks chitin-binding and C-terminal extension domains, showing homology to other plant class II chitinases.
• The CAChi2 gene is present as a single or low-copy number gene in the pepper genome.
• CAChi2 mRNA expression was upregulated in incompatible interactions with Xanthomonas campestris pv. vesicatoria and Phytophthora capsici.
• Ethylene-releasing ethephon strongly induced CAChi2 transcript accumulation, while other tested compounds had no significant effect.

Conclusions:

• CAChi2 represents a novel class II chitinase in pepper.
• Its expression is induced by specific pathogen infections and ethylene, suggesting a role in plant defense mechanisms.