Nasiri Ehsan, Shekari Fariborz, Abbasi Amin, Morshedloo Mohammad Reza, Ghorbanpour Mansour
Department of Plant Production and Genetics, Faculty of Agriculture, University of Maragheh, Maragheh, Iran.
Department of Horticultural Science, Faculty of Agriculture, University of Maragheh, Maragheh, Iran.
BMC Plant Biol. 2025 Mar 15;25(1):336. doi: 10.1186/s12870-025-06323-1.
Drought stress is one of the most significant environmental challenges, leading to various changes in the physiological processes of plants. Gamma-aminobutyric acid (GABA) is an essential biomolecule that plays a critical role in regulating growth and stress signaling. The current study aims to investigate the effects of GABA on antioxidant enzyme activity and the essential oil composition of Thymus daenensis Celak under different levels of water deficit stress. We examined three different levels of soil moisture (90%, 60%, and 30% of field capacity) alongside three GABA foliar treatments (0 mM, 25 mM, 50 mM, and 75 mM). The results showed that applying 25 mM GABA under severe stress conditions (at 30% of field capacity) significantly increased the activity levels of ascorbate peroxidase, guaiacol peroxidase, and superoxide dismutase enzymes by 95.5%, 78.45%, and 38%, respectively. Additionally, applying GABA at various levels during different water stress treatments led to significant improvements in the chlorophyll, carotenoid, and proline content in leaf tissues. Specifically, the application of 25, 50, and 75 mM GABA enhanced the proline content in T. daenensis by 53.9%, 26.8%, and 11%, respectively, compared to the control group (non-application of GABA). Essential oil analysis revealed the following ranges: thymol was present in the range of 38.07-45.18%, cymene in the range of 5.13-14.10%, caryophyllene in the range of 4.3-23.01%, and cineole in the range of 2-4.15%. The highest amount of thymol was obtained in the absence of GABA at 30% field capacity, while the greatest amount of cymene was also observed without GABA at 90% field capacity. Additionally, the maximum concentration of caryophyllene was found when 50 mM GABA was applied at 90% field capacity, and the maximum level of cineole was detected with 75 mM GABA at 90% field capacity. In conclusion, the exogenous application of GABA demonstrated favorable efficacy, particularly at a concentration of 25 mM. This treatment resulted in a significant enhancement of the plant's defense mechanisms and created favorable conditions that notably impacted the quality of the essential oil produced by T. daenensis.
干旱胁迫是最严峻的环境挑战之一，会导致植物生理过程发生各种变化。γ-氨基丁酸（GABA）是一种重要的生物分子，在调节生长和应激信号传导中起着关键作用。本研究旨在探讨不同水分亏缺胁迫水平下，GABA对百里香抗氧化酶活性和精油成分的影响。我们研究了三种不同的土壤湿度水平（田间持水量的90%、60%和30%）以及三种GABA叶面处理（0 mM、25 mM、50 mM和75 mM）。结果表明，在重度胁迫条件下（田间持水量的30%）施用25 mM GABA，显著提高了抗坏血酸过氧化物酶、愈创木酚过氧化物酶和超氧化物歧化酶的活性水平，分别提高了95.5%、78.45%和38%。此外，在不同水分胁迫处理期间施用不同水平的GABA，显著改善了叶片组织中的叶绿素、类胡萝卜素和脯氨酸含量。具体而言，与对照组（未施用GABA）相比，施用25 mM、50 mM和75 mM GABA分别使百里香中的脯氨酸含量提高了53.9%、26.8%和11%。精油分析结果如下：百里香酚含量在38.07 - 45.18%之间，对异丙基甲苯含量在5.13 - 14.10%之间，石竹烯含量在4.3 - 23.01%之间，桉叶素含量在2 - 4.15%之间。在田间持水量30%且未施用GABA的情况下，百里香酚含量最高；在田间持水量90%且未施用GABA的情况下，对异丙基甲苯含量也最高。此外，在田间持水量90%时施用50 mM GABA，石竹烯浓度最高；在田间持水量90%时施用75 mM GABA，桉叶素含量最高。总之，外源施用GABA显示出良好的效果，尤其是在浓度为25 mM时。这种处理显著增强了植物的防御机制，并创造了有利条件，对百里香产生的精油质量产生了显著影响。
