Maize Endochitinase Expression in Response to Fall Armyworm Herbivory

Area of Science:

• Plant science
• Entomology
• Biochemistry

Background:

• Insect damage, particularly from caterpillars, causes significant crop loss.
• Plant chitinases offer a sustainable alternative to chemical insecticides by degrading caterpillar peritrophic matrix (PM).

Purpose of the Study:

• To identify maize chitinase candidates for enhanced plant resistance against caterpillar pests.
• To investigate the role of specific maize chitinases in response to fall armyworm (Spodoptera frugiperda) attack.

Main Methods:

• Characterization of five endochitinase classes in the maize genome.
• Isolation and cloning of four maize chitinase genes (chitinase A, B, I, PRm3) from two inbred lines (Mp708, Tx601).
• Analysis of chitinase gene expression and activity in response to fall armyworm feeding and mechanical wounding; scanning electron microscopy of caterpillar peritrophic matrix.

Main Results:

• Chitinase transcript abundance and enzymatic activity increased in maize following fall armyworm feeding and wounding.
• Maize chitinases were active within the caterpillar midgut, food bolus, and frass.
• Peritrophic matrices of caterpillars fed on resistant maize (Tx601) showed structural damage; chitinase PRm3 was implicated as a potential insecticidal protein.

Conclusions:

• Maize chitinases are induced by fall armyworm attack and exhibit insecticidal activity.
• Chitinase PRm3 in the Tx601 maize inbred line is a promising candidate for developing insect-resistant crops.