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Abstract <p>Orchidaceae, one of the largest and most ecologically diverse plant families, is increasingly threatened by a wide spectrum of abiotic stresses, including drought, salinity, and extreme temperatures, which frequently lead to oxidative imbalance due to excessive production of reactive oxygen species (ROS). These stresses severely restrict physiological performance, impair morphological development, disrupt cellular metabolism, and ultimately limit the genetic potential and survival of orchid species both in natural habitats and in commercial cultivation. Abiotic stress triggers extensive physiological, biochemical, and molecular reprogramming in orchids, including alterations in photosynthetic efficiency, osmotic homeostasis, antioxidant defense, ion transport, and secondary metabolite biosynthesis. Stress perception begins with the activation of sensor molecules that detect environmental changes and initiate signal transduction cascades involving calcium fluxes, mitogen-activated protein kinase (MAPK) pathways, abscisic acid (ABA)-dependent sucrose non-fermenting 1–related kinase (SnRK) signaling, ROS-mediated responses, and complex hormonal crosstalk. These signaling networks activate transcription factors such as DREB, WRKY, NAC, bZIP, and ERF, which regulate downstream genes essential for stress tolerance. Orchids also employ long-term epigenetic mechanisms, including histone modifications and DNA methylation, to fine-tune stress-responsive gene expression. Furthermore, adaptations including crassulacean acid metabolism (CAM) photosynthesis, velamen-mediated water regulation, mycorrhizal associations, and the production of protective proteins and osmolytes contribute to their resilience. This review synthesizes current advances in understanding the physiological and molecular mechanisms of abiotic stress tolerance in orchids, highlighting the integrated roles of signal perception, transcriptional regulation, metabolic adjustment, and symbiotic interactions. Improved insight into these mechanisms will support conservation strategies, enhance breeding for stress-resilient cultivars, and promote sustainable orchid production under increasingly challenging environmental conditions.</p>

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Physiological and Molecular Mechanisms of Abiotic Stress Tolerance in Orchids: A Comprehensive Review

  • 期刊论文

  • 发表日期：

    2026年5月7日

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  • D. Nivedha,
  • V.A. Sathiyamurthy,
  • S. Padmapriya,
  • N. Saranya,
  • D. Amirtham,
  • M. Karthikeyan

摘要

Abstract

Orchidaceae, one of the largest and most ecologically diverse plant families, is increasingly threatened by a wide spectrum of abiotic stresses, including drought, salinity, and extreme temperatures, which frequently lead to oxidative imbalance due to excessive production of reactive oxygen species (ROS). These stresses severely restrict physiological performance, impair morphological development, disrupt cellular metabolism, and ultimately limit the genetic potential and survival of orchid species both in natural habitats and in commercial cultivation. Abiotic stress triggers extensive physiological, biochemical, and molecular reprogramming in orchids, including alterations in photosynthetic efficiency, osmotic homeostasis, antioxidant defense, ion transport, and secondary metabolite biosynthesis. Stress perception begins with the activation of sensor molecules that detect environmental changes and initiate signal transduction cascades involving calcium fluxes, mitogen-activated protein kinase (MAPK) pathways, abscisic acid (ABA)-dependent sucrose non-fermenting 1–related kinase (SnRK) signaling, ROS-mediated responses, and complex hormonal crosstalk. These signaling networks activate transcription factors such as DREB, WRKY, NAC, bZIP, and ERF, which regulate downstream genes essential for stress tolerance. Orchids also employ long-term epigenetic mechanisms, including histone modifications and DNA methylation, to fine-tune stress-responsive gene expression. Furthermore, adaptations including crassulacean acid metabolism (CAM) photosynthesis, velamen-mediated water regulation, mycorrhizal associations, and the production of protective proteins and osmolytes contribute to their resilience. This review synthesizes current advances in understanding the physiological and molecular mechanisms of abiotic stress tolerance in orchids, highlighting the integrated roles of signal perception, transcriptional regulation, metabolic adjustment, and symbiotic interactions. Improved insight into these mechanisms will support conservation strategies, enhance breeding for stress-resilient cultivars, and promote sustainable orchid production under increasingly challenging environmental conditions.