Beneficial Bacteria Help Cactus Pear Survive Severe Drought by Boosting Nitrogen and Metabolic Defenses

Beneficial Bacteria Help Cactus Pear Survive Drought by Enhancing Nitrogen Use and Metabolic Resilience

A newly published study in Scientific Reports demonstrates that plant growth-promoting bacteria (PGPB) can significantly strengthen cactus pear plants against drought, particularly under conditions of limited nitrogen availability. The research evaluated how three bacterial strains—Paenibacillus sp. IPACC38, Paenibacillus sp. IPACC55 and Bacillus subtilis IPACC29—affect growth, metabolism, and nitrogen accumulation in Opuntia cochenillifera (“Miúda” cultivar).

Drought Strongly Reduced Growth Across All Treatments

Under water limitation (25% field capacity), cactus pear plants experienced substantial reductions in plant height, number of cladodes, cladode area, biomass, and root growth. These impacts were visible even after 150 days of drought exposure.

Despite the severe stress, plants inoculated with IPACC29 and IPACC38—especially without nitrogen fertilization—showed the most robust performance compared to all other treatments.

PGPB Enhanced Nitrogen Accumulation and Root Development

Nitrogen was a key factor in drought resilience.

Inoculated plants without nitrogen showed higher nitrogen content and accumulation in cladodes and roots.
The Bacillus subtilis strain IPACC29 showed a strong ability to increase root nitrogen levels, which correlated with better biomass and water status.

This increased nitrogen availability supported the maintenance of essential photosynthetic pigments, contributing to physiological stability during drought.

Metabolic Adjustments Improved Stress Tolerance

The study found that drought-induced increases in chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids were strongly connected to bacterial inoculation effects.

Carotenoid accumulation helped reduce oxidative stress.
Inoculated plants displayed specific regulation of soluble carbohydrates and free amino acids, enhancing osmotic adjustment and metabolic flexibility.

Root Architecture Was Better Preserved with Bacterial Inoculation

Severe drought impaired root system development in all treatments, but plants inoculated with IPACC29 without nitrogen showed noticeably superior root length and structure compared to uninoculated plants.

Statistical Analyses Confirmed Bacterial Influence

Principal Component Analysis (PCA) and correlation networks revealed clear clustering patterns:

Under drought, IC29 and IC38 formed distinct groups associated with better nitrogen dynamics, pigment regulation, and stress tolerance.
Uninoculated plants clustered separately, showing lower physiological performance.

Sustainable Strategy for Dry Regions

The authors conclude that IPACC29, IPACC38, and IPACC55 are promising microbial tools for enhancing cactus pear productivity under drought and low-nitrogen conditions. Their application can reduce dependence on chemical fertilizers while supporting forage production in semiarid regions.

Summary

Reference

Dauala, G.A., Fonseca, B.S.F., Sousa, A.B. et al. Plant growth-promoting bacteria modulate metabolism and nitrogen accumulation to counteract drought damage in cactus pear plants. Sci Rep 15, 36432 (2025). https://doi.org/10.1038/s41598-025-20509-5