Aktas Nagihan, Farouk Saad, Al-Ghamdi Amal Ahmed Mohammed, Alenazi Ahmed S, AlMalki Mona Abdulaziz Labeed, Dinler Burcu Seckin
Department of Biology, Faculty of Arts and Science, Sinop University, Sinop 57000, Turkey.
Agricultural Botany Department, Faculty of Agriculture, Mansoura University, Mansoura 35516, Egypt.
Plants (Basel). 2025 Jun 25;14(13):1949. doi: 10.3390/plants14131949.
While pipecolic acid (Pip) mediates morpho-physiological and molecular responses during biotic stress, its roles under drought remain an inexpressible mystery. The investigation aimed to elucidate the roles of a 30μM Pip pretreatment in alleviating drought injury on barley ( L. cv, Bülbül89) seedlings. Pip pretreatment under normal or drought conditions lowered the osmotic potential (Ψs) and water saturation deficit (WSD), while optimizing the relative water content (RWC), triggered osmotically energetic molecules (OEM) and salicylic acid (SA) accumulation, improving osmotic adjustment (OA), and boosting water retention and uptake capacity (WTC, and WUC), alongwith a considerable improvement in seedling growth over non-treated plants under such conditions. Additionally, Pip pretreatment improved chlorophyll (Chl), the chlorophyll stability index (CSI), pheophytin, chlorophyllide (chlide), chlorophyllide (chlide), chl/chlide, chl/chlide, protoporphyrin, Mg-protoporphyrin, protochlorophyllide, and photosynthetic performance over non-treated plants under such conditions. Pip pretreatment preserves redox homeostasis in drought-stressed plants by accumulating antioxidant solutes alongside the activation of superoxide dismutase and glutathione reductase over non-treated plants. Drought distinctly reduced Ψs (more negative), RWC, photosynthetic pigment, CSI, chlorophyll assimilation intermediate, and photosynthetic performance, with an increment in chlorophyll degradation intermediate and nonenzymatic antioxidant solutes. Drought maintains OA capacity via a hyper-accumulation of OEM and SA, which results in higher WSD, WTC, and WUC. Drought triggered an oxidative burst, which was associated with a decline in the membrane stability index. These findings highlight Pip's capability for lessening drought stress-induced restriction in barley seedlings via bolstering oxidative homeostasis, OA capacity, and stabilizing chlorophyll biosynthesis. Future research must elucidate the precise molecular mechanisms underlying Pip's action in alleviating drought injury.
虽然哌啶酸（Pip）在生物胁迫期间介导形态生理和分子反应，但其在干旱条件下的作用仍是一个难以言表的谜团。本研究旨在阐明30μM Pip预处理在减轻大麦（L. cv, Bülbül89）幼苗干旱伤害中的作用。正常或干旱条件下的Pip预处理降低了渗透势（Ψs）和水分饱和亏缺（WSD），同时优化了相对含水量（RWC），触发了渗透能分子（OEM）和水杨酸（SA）的积累，改善了渗透调节（OA），并提高了保水和吸水能力（WTC和WUC），与未处理植株相比，在此条件下幼苗生长有显著改善。此外，与未处理植株相比，Pip预处理提高了叶绿素（Chl）、叶绿素稳定性指数（CSI）、脱镁叶绿素、叶绿素酸酯（chlide）、叶绿素酸酯（chlide）、chl/chlide、chl/chlide、原卟啉、镁原卟啉、原叶绿素酸酯以及光合性能。Pip预处理通过积累抗氧化溶质以及比未处理植株激活超氧化物歧化酶和谷胱甘肽还原酶，维持干旱胁迫植株的氧化还原稳态。干旱显著降低了Ψs（更负）、RWC、光合色素、CSI、叶绿素同化中间体和光合性能，同时叶绿素降解中间体和非酶抗氧化溶质增加。干旱通过OEM和SA的过度积累维持OA能力，这导致更高的WSD、WTC和WUC。干旱引发了氧化爆发，这与膜稳定性指数的下降有关。这些发现突出了Pip通过增强氧化稳态、OA能力和稳定叶绿素生物合成来减轻干旱胁迫对大麦幼苗造成的限制的能力。未来的研究必须阐明Pip减轻干旱伤害作用的精确分子机制。
