Unlocking the Role of Rice Root Metabolites in Modulating Meloidogyne graminicola Chemotaxis

Area of Science:

• Plant-Pathology
• Agricultural Entomology
• Biochemistry

Background:

• Root-knot nematodes, such as *Meloidogyne graminicola*, are significant pests of rice.
• Plant-parasitic nematodes exhibit chemotaxis, responding to chemical cues released by host plants.
• Understanding this chemical communication is key to developing sustainable nematode management.

Purpose of the Study:

• To investigate the role of rice root exudates in modulating the chemotactic behavior of *Meloidogyne graminicola*.
• To identify cultivar-specific differences in root metabolites influencing nematode attraction.
• To explore potential semiochemicals for sustainable nematode control in rice.

Main Methods:

• Olfactometer and attraction assays were performed using two rice cultivars: Pusa Basmati 1121 (susceptible) and Kalo Bhutia 213 (resistant).
• Root exudates and volatile organic compounds (VOCs) were extracted and analyzed using Gas Chromatography-Mass Spectrometry (GC-MS).
• Metabolite profiles were analyzed using Principal Component Analysis (PCA), Partial Least Squares Discriminant Analysis (PLS-DA), and pathway enrichment analysis.

Main Results:

• *Meloidogyne graminicola* showed significantly higher attraction to the susceptible cultivar PB 1121 compared to the resistant cultivar KB 213.
• GC-MS analysis and multivariate statistical methods identified cultivar-specific bioactive metabolites.
• Discriminant analysis pinpointed specific semiochemicals responsible for modulating nematode chemotaxis.

Conclusions:

• Rice cultivars differ in their chemical profiles, influencing nematode attraction.
• Specific bioactive semiochemicals in root exudates play a crucial role in rice-nematode interactions.
• These identified semiochemicals represent a promising basis for developing eco-friendly and cost-effective nematode management strategies in rice.