# Hydrogen Peroxide and Vitexin in the Signaling and Defense Responses of Passiflora incarnata Under Drought Stress

## TL;DR

This study shows that hydrogen peroxide helps passionflower plants survive drought by improving water conservation and recovery after stress.

## Contribution

The study reveals how hydrogen peroxide and specific compounds aid in drought acclimation and recovery in Passiflora incarnata.

## Key findings

- H2O2 treatment reduced stomatal conductance and transpiration, aiding water conservation under drought.
- H2O2 increased antioxidant enzyme activity and improved post-stress recovery of photosynthetic parameters.
- Vitexin, arabinose, and trehalose likely support membrane protection and photochemical recovery during drought.

## Abstract

Hydrogen peroxide (H2O2) functions as a signaling molecule that triggers physiological and biochemical adjustments that help plants cope with environmental stress. This study evaluated the effects of foliar application of 1.5 mM H2O2 on the physiological and biochemical responses of Passiflora incarnata subjected to 14 days of drought stress followed by 5 days of rehydration. Drought reduced Fv/Fm and photochemical efficiency, as well as stomatal conductance and transpiration rates. H2O2 treatment under drought further reduced stomatal conductance and transpiration, suggesting enhanced water conservation. Drought-stressed plants treated with H2O2 exhibited increased concentrations of glucose, fructose, and mannose along with reduced sucrose levels, indicating osmotic adjustment and energy mobilization. Enzymatic antioxidant activity, particularly that of superoxide dismutase and catalase, increased with H2O2 treatment, while peroxidase activity remained low. The content of vitexin, arabinose, and trehalose decreased under drought, likely due to their roles in membrane protection, as MDA levels remained stable. After rehydration, Fv/Fm and ΦPSII recovered, and H2O2-treated plants showed higher carbon assimilation and carboxylation efficiency. These results indicate that H2O2 promotes drought acclimation and enhances post-stress recovery in P. incarnata. We conclude that H2O2 induces signaling pathways, with trehalose, arabinose, and vitexin contributing to the regeneration of the photochemical apparatus, as well as defense and acclimation under drought conditions.