Tasmanian Institute of Agriculture, University of Tasmania, Prospect 7250, Australia.
International Research Centre for Environmental Membrane Biology, Foshan University, Foshan 528000, China.
Biomolecules. 2021 May 24;11(6):788. doi: 10.3390/biom11060788.
Soil salinity is one of the major abiotic stresses restricting plant growth and development. Application of plant growth regulators (PGRs) is a possible practical means for minimizing salinity-induced yield losses, and can be used in addition to or as an alternative to crop breeding for enhancing salinity tolerance. The PGRs auxin, cytokinin, nitric oxide, brassinosteroid, gibberellin, salicylic acid, abscisic acid, jasmonate, and ethylene have been advocated for practical use to improve crop performance and yield under saline conditions. This review summarizes the current knowledge of the effectiveness of various PGRs in ameliorating the detrimental effects of salinity on plant growth and development, and elucidates the physiological and genetic mechanisms underlying this process by linking PGRs with their downstream targets and signal transduction pathways. It is shown that, while each of these PGRs possesses an ability to alter plant ionic and redox homeostasis, the complexity of interactions between various PGRs and their involvement in numerous signaling pathways makes it difficult to establish an unequivocal causal link between PGRs and their downstream effectors mediating plants' adaptation to salinity. The beneficial effects of PGRs are also strongly dependent on genotype, the timing of application, and the concentration used. The action spectrum of PGRs is also strongly dependent on salinity levels. Taken together, this results in a rather narrow "window" in which the beneficial effects of PGR are observed, hence limiting their practical application (especially under field conditions). It is concluded that, in the light of the above complexity, and also in the context of the cost-benefit analysis, crop breeding for salinity tolerance remains a more reliable avenue for minimizing the impact of salinity on plant growth and yield. Further progress in the field requires more studies on the underlying cell-based mechanisms of interaction between PGRs and membrane transporters mediating plant ion homeostasis.
土壤盐度是限制植物生长和发育的主要非生物胁迫因素之一。应用植物生长调节剂（PGRs）是减轻盐胁迫导致产量损失的一种可行的实际手段，它可以与作物育种相结合，作为增强盐度耐受性的一种替代方法。生长素、细胞分裂素、一氧化氮、油菜素内酯、赤霉素、水杨酸、脱落酸、茉莉酸和乙烯等 PGR 已被提倡用于在盐胁迫条件下改善作物的性能和产量。本综述总结了各种 PGR 在减轻盐对植物生长和发育的不利影响方面的有效性，通过将 PGR 与其下游靶标和信号转导途径联系起来，阐明了这一过程的生理和遗传机制。结果表明，虽然这些 PGR 中的每一种都具有改变植物离子和氧化还原稳态的能力，但各种 PGR 之间相互作用的复杂性以及它们参与众多信号通路，使得很难在 PGR 与其下游效应子之间建立明确的因果关系，而这些效应子介导植物对盐度的适应。PGR 的有益效果也强烈依赖于基因型、应用时间和使用浓度。PGR 的作用光谱也强烈依赖于盐度水平。总之，这导致了一个相当狭窄的“窗口”，在这个窗口中可以观察到 PGR 的有益效果，从而限制了它们的实际应用（特别是在田间条件下）。结论是，鉴于上述复杂性，以及成本效益分析的背景，耐盐作物育种仍然是减轻盐度对植物生长和产量影响的更可靠途径。该领域的进一步进展需要更多研究 PGR 与介导植物离子稳态的膜转运体之间相互作用的基础细胞机制。
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