Ghosh Totan Kumar, Tompa Naznin Haque, Rahman Md Mezanur, Mohi-Ud-Din Mohammed, Al-Meraj S M Zubair, Biswas Md Sanaullah, Mostofa Mohammad Golam
Department of Crop Botany, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, Bangladesh.
Institute of Genomics for Crop Abiotic Stress Tolerance, Department of Plant and Soil Science, Texas Tech University, Lubbock, Texas, United States.
PeerJ. 2021 Nov 10;9:e12419. doi: 10.7717/peerj.12419. eCollection 2021.
Liverwort is considered as the key species for addressing a myriad of questions in plant biology. Exploration of drought tolerance mechanism(s) in this group of land plants offers a platform to identify the early adaptive mechanisms involved in drought tolerance. The current study aimed at elucidating the drought acclimation mechanisms in liverwort's model . The gemmae, asexual reproductive units of , were exposed to sucrose (0.2 M), mannitol (0.5 M) and polyethylene glycol (PEG, 10%) for inducing physiological drought to investigate their effects at morphological, physiological and biochemical levels. Our results showed that drought exposure led to extreme growth inhibition, disruption of membrane stability and reduction in photosynthetic pigment contents in . The increased accumulation of hydrogen peroxide and malondialdehyde, and the rate of electrolyte leakage in the gemmalings of indicated an evidence of drought-caused oxidative stress. The gemmalings showed significant induction of the activities of key antioxidant enzymes, including superoxide dismutase, catalase, ascorbate peroxidase, dehydroascorbate reductase and glutathione -transferase, and total antioxidant activity in response to increased oxidative stress under drought. Importantly, to counteract the drought effects, the gemmalings also accumulated a significant amount of proline, which coincided with the evolutionary presence of proline biosynthesis gene () in land plants. Furthermore, the application of exogenous abscisic acid (ABA) reduced drought-induced tissue damage and improved the activities of antioxidant enzymes and accumulation of proline, implying an archetypal role of this phytohormone in for drought tolerance. We conclude that physiological drought tolerance mechanisms governed by the cellular antioxidants, proline and ABA were adopted in liverwort , and that these findings have important implications in aiding our understanding of osmotic stress acclimation processes in land plants.
地钱被认为是解决植物生物学中众多问题的关键物种。探索这类陆地植物的耐旱机制为识别参与耐旱的早期适应机制提供了一个平台。当前的研究旨在阐明地钱模式植物的干旱适应机制。地钱的无性繁殖单位——芽孢，被置于蔗糖（0.2M）、甘露醇（0.5M）和聚乙二醇（PEG，10%）中以诱导生理干旱，从而在形态、生理和生化水平上研究它们的影响。我们的结果表明，干旱胁迫导致地钱生长极度受抑、膜稳定性破坏以及光合色素含量降低。过氧化氢和丙二醛积累增加，以及地钱芽孢苗中的电解质渗漏率表明存在干旱引起的氧化应激证据。地钱芽孢苗显示出关键抗氧化酶活性的显著诱导，包括超氧化物歧化酶、过氧化氢酶、抗坏血酸过氧化物酶、脱氢抗坏血酸还原酶和谷胱甘肽 - 转移酶，以及在干旱下因氧化应激增加而产生的总抗氧化活性。重要的是，为了抵消干旱影响，地钱芽孢苗还积累了大量脯氨酸，这与陆地植物中脯氨酸生物合成基因（）的进化存在相一致。此外，外源脱落酸（ABA）的应用减少了干旱诱导的组织损伤，并提高了抗氧化酶活性和脯氨酸积累，这意味着这种植物激素在地钱耐旱中具有原型作用。我们得出结论，地钱采用了由细胞抗氧化剂、脯氨酸和ABA调控的生理耐旱机制，并且这些发现对于帮助我们理解陆地植物的渗透胁迫适应过程具有重要意义。
