Augmenting Rice Defenses: Exogenous Calcium Elevates GABA Levels Against WBPH Infestation

Area of Science:

• Plant Science
• Agricultural Science
• Biochemistry

Background:

• White-backed planthopper (WBPH) infestation severely impacts rice yield and quality.
• Understanding plant responses to pest stress is crucial for developing sustainable agriculture.
• Exogenous application of nutrients and signaling molecules can modulate plant defense mechanisms.

Purpose of the Study:

• To investigate the effects of calcium and gamma-aminobutyric acid (GABA) on rice growth and stress tolerance under WBPH infestation.
• To elucidate the physiological and biochemical mechanisms underlying the protective effects of calcium and GABA.
• To assess the potential of these supplements in mitigating WBPH damage.

Main Methods:

• Rice plants were subjected to WBPH infestation with or without calcium and GABA supplementation.
• Phenotypic traits (shoot/root length, leaf width, tiller number, panicle length, relative water content) were measured.
• Physiological markers including oxidative stress indicators (H2O2, O2•−, electrolyte leakage), antioxidant enzyme activities (CAT, POD, SOD), hormone levels (ABA, SA), and amino acid biosynthesis were analyzed.
• Calcium's role in regulating the GABA shunt pathway and ion homeostasis was examined.

Main Results:

• WBPH stress significantly reduced rice growth parameters, but calcium and GABA supplementation enhanced shoot and root length.
• Both supplementations decreased oxidative stress markers and electrolyte leakage.
• GABA significantly boosted antioxidant enzyme activities (CAT, POD, SOD) under stress.
• Calcium and GABA increased stress hormone accumulation (ABA, SA), promoted stomatal closure, and enhanced water conservation.
• Calcium regulated the GABA shunt pathway, increasing GABA and succinate levels.
• Supplementation improved amino acid biosynthesis and ion homeostasis (Ca, Fe, Mg).

Conclusions:

• Exogenous calcium and GABA effectively enhance rice tolerance to WBPH infestation.
• These supplements modulate key physiological and biochemical pathways, including antioxidant defense, hormone signaling, and nutrient uptake.
• Calcium and GABA represent promising strategies for sustainable pest management in rice cultivation.