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<p>This study aimed to elucidate the molecular mechanism of low molecular weight chitosan (LMWC) enhancing drought tolerance of sugarcane (<i>Saccharum</i> spp.), the seedcane cuttings were soaked with 100&#xa0;mg/L LMWC solution. Physiological and comparative proteomic analyses were conducted under natural drought stress in pot experiments. The results showed that LMWC pretreatment significantly increased the leaf relative water content (RWC), levels of osmoregulatory compounds (soluble sugars and proteins), chlorophyll b and total chlorophyll (<i>P</i> &lt; 0.05), while concurrently reduced the malondialdehyde (MDA) levels, an indicator of oxidative damage. Furthermore, LMWC pretreatment promoted plant growth and increased the plant height and stem diameter. The key LMWC-modulated drought-responsive proteins were identified by utilizing two-dimensional electrophoresis (2-DE) coupled with Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF-TOF/MS). Upregulation of isoflavone reductase-like proteins (IRL) was detected which could enhance the ROS scavenging capacity. Synergistic upregulation of cytochrome b6/f complex (PetN) and oxygen-evolving enhancer protein 2 (OEE2) might optimize the photochemical efficiency. Upregulation of actin cross-linking protein (ACLP) might potentially mediate stomatal closure and reinforce cellular integrity. Upregulation of RNA helicase (RH) could accelerate stress-responsive protein synthesis. Crucially, downregulation of aspartate aminotransferase (pAspAT) might redirect carbon/nitrogen (C/N) metabolic flux, directing carbon flux toward the Calvin cycle to enhance CO₂ fixation efficiency. The differentially expressed proteins were predominated by alkaline hydrophilic transmembrane proteins characterized by alanine-rich hydrophobic domains. It is proposed that hydrophobic interactions within these domains confer structural stability. The structural synergy between specific protein motifs and osmolytes provides a possible mechanism for cellular dehydration defense. In summary, the present study revealed a four-dimensional LMWC regulatory framework for underpinning drought tolerance enhancement, encompassing ROS elimination, dehydration protection, photosynthetic maintenance, and cellular stabilization. These findings provide a theoretical foundation for stress-resilient cultivation and promising molecular targets for crop improvement in sugarcane.</p>

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Comparative Proteomic Insights into Low Molecular Weight Chitosan-Induced Drought Tolerance in Sugarcane

  • 期刊论文

  • 发表日期：

    2026年1月12日

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  • Gui Zhou,
  • Xiao-Xia Liu,
  • Li-Hang Qiu,
  • Cheng-Lin Zou,
  • Yang-Rui Li

摘要

This study aimed to elucidate the molecular mechanism of low molecular weight chitosan (LMWC) enhancing drought tolerance of sugarcane (Saccharum spp.), the seedcane cuttings were soaked with 100 mg/L LMWC solution. Physiological and comparative proteomic analyses were conducted under natural drought stress in pot experiments. The results showed that LMWC pretreatment significantly increased the leaf relative water content (RWC), levels of osmoregulatory compounds (soluble sugars and proteins), chlorophyll b and total chlorophyll (P < 0.05), while concurrently reduced the malondialdehyde (MDA) levels, an indicator of oxidative damage. Furthermore, LMWC pretreatment promoted plant growth and increased the plant height and stem diameter. The key LMWC-modulated drought-responsive proteins were identified by utilizing two-dimensional electrophoresis (2-DE) coupled with Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF-TOF/MS). Upregulation of isoflavone reductase-like proteins (IRL) was detected which could enhance the ROS scavenging capacity. Synergistic upregulation of cytochrome b6/f complex (PetN) and oxygen-evolving enhancer protein 2 (OEE2) might optimize the photochemical efficiency. Upregulation of actin cross-linking protein (ACLP) might potentially mediate stomatal closure and reinforce cellular integrity. Upregulation of RNA helicase (RH) could accelerate stress-responsive protein synthesis. Crucially, downregulation of aspartate aminotransferase (pAspAT) might redirect carbon/nitrogen (C/N) metabolic flux, directing carbon flux toward the Calvin cycle to enhance CO₂ fixation efficiency. The differentially expressed proteins were predominated by alkaline hydrophilic transmembrane proteins characterized by alanine-rich hydrophobic domains. It is proposed that hydrophobic interactions within these domains confer structural stability. The structural synergy between specific protein motifs and osmolytes provides a possible mechanism for cellular dehydration defense. In summary, the present study revealed a four-dimensional LMWC regulatory framework for underpinning drought tolerance enhancement, encompassing ROS elimination, dehydration protection, photosynthetic maintenance, and cellular stabilization. These findings provide a theoretical foundation for stress-resilient cultivation and promising molecular targets for crop improvement in sugarcane.