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This research aims to understand the molecular mechanisms of heat acclimation in kiwifruit, focusing on gene interactions that enhance plant recovery under heat stress.

May 9, 2026Frontiers in Plant Science0 citationsOpen Access

Heat acclimation induces AcLBD1 activated AcHSFA2s mutual amplification cascade for rapid recovery of root vitality and leaf photosynthesis in kiwifruit

KZKe-jia Zhang FLFang Li LCLu-lu Chen

Key Points

This research aims to understand the molecular mechanisms of heat acclimation in kiwifruit, focusing on gene interactions that enhance plant recovery under heat stress.
Investigated heat acclimation from 35 °C to 45 °C in kiwifruit.
Used transcriptomics to identify key genes involved in thermotolerance.
Conducted comparisons of wild-type and loss-of-function mutant kiwifruit strains.
AcHSFA2-2 overexpression increased root vitality by 4.13-fold post-heat stress.
The achsfa2-1 mutant displayed severely impaired thermotolerance and reduced AcHSFA2-2 expression.
The AcLBD1-AcHSFA2 cascade was found to regulate the expression of AcHSP20s, enhancing heat resilience.

Abstract

Introduction Kiwifruit ( Actinidia spp.) is a succulent, shallow-rooted perennial fruit tree highly sensitive to environmental fluctuations, particularly the increasingly frequent extreme heat events. Methods This study investigated heat acclimation (HA) involving a transition from mild (35 °C) to extreme (45 °C) heat stress in heat-sensitive kiwifruit, aiming to elucidate the molecular biological mechanisms underlying HA responses in perennial plants. Results Results revealing the enhanced recovery of plants under 55 °C stress via improved root vitality and photosynthesis. Transcriptomics identified AcLBD1 as a key acclimation-responsive gene that upregulates AcHSFA2-1 . The achsfa2-1 loss-of-function mutant displayed completely impaired thermotolerance, with significantly suppressed expression of AcHSFA2-2 in its transcriptome. Overexpressing AcHSFA2-2 increased root vitality as high as 4.13‑fold and boosted post‑heat‑stress recovery of 35S:: AcHSFA2-2 kiwifruit. Moreover, AcHSFA2‑1 and AcHSFA2‑2 form a positive feedback loop, that AcHSFA2‑1 significantly enhanced the promoter vitality of AcHSFA2-2 , and vice versa. And the AcLBD1‑AcHSFA2s module co‑activates AcHSP20s encoding heat-protective proteins (with AcHSFA2s more potent than AcLBD1). Discussion These findings establish a LBD‑HSFA2‑HSP20 cascade network governing heat resilience via root and photosynthetic recovery, advancing the molecular basis of plant heat acclimation.

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