Main conclusion

Silicon application mitigates phosphate deficiency in barley through an interplay with auxin and nitric oxide, enhancing growth, photosynthesis, and redox balance, highlighting the potential of silicon as a fertilizer for overcoming nutritional stresses.

Abstract

Silicon (Si) is reported to attenuate nutritional stresses in plants, but studies on the effect of Si application to plants grown under phosphate (Pi) deficiency are still very scarce, especially in barley. Therefore, the present work was undertaken to investigate the potential role of Si in mitigating the adverse impacts of Pi deficiency in barley Hordeum vulgare L. (var. BH902). Further, the involvement of two key regulatory signaling molecules––auxin and nitric oxide (NO)––in Si-induced tolerance against Pi deficiency in barley was tested. Morphological attributes, photosynthetic parameters, oxidative stress markers (O₂^·−, H₂O₂, and MDA), antioxidant system (enzymatic––APX, CAT, SOD, GR, DHAR, MDHAR as well as non-enzymatic––AsA and GSH), NO content, and proline metabolism were the key traits that were assessed under different treatments. The P deficiency distinctly declined growth of barley seedlings, which was due to enhancement in oxidative stress leading to inhibition of photosynthesis. These results were also in parallel with an enhancement in antioxidant activity, particularly SOD and CAT, and endogenous proline level and its biosynthetic enzyme (P5CS). The addition of Si exhibited beneficial effects on barley plants grown in Pi-deficient medium as reflected in increased growth, photosynthetic activity, and redox balance through the regulation of antioxidant machinery particularly ascorbate–glutathione cycle. We noticed that auxin and NO were also found to be independently participating in Si-mediated improvement of growth and other parameters in barley roots under Pi deficiency. Data of gene expression analysis for PHOSPHATE TRANSPORTER1 (HvPHT1) indicate that Si helps in increasing Pi uptake as per the need of Pi-deficient barley seedlings, and also auxin and NO both appear to help Si in accomplishing this task probably by inducing lateral root formation. These results are suggestive of possible application of Si as a fertilizer to correct the negative effects of nutritional stresses in plants. Further research at genetic level to understand Si-induced mechanisms for mitigating Pi deficiency can be helpful in the development of new varieties with improved tolerance against Pi deficiency, especially for cultivation in areas with Pi-deficient soils.

中文翻译：

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硅通过参与大麦根中的生长素和一氧化氮来调节磷酸盐缺乏

主要结论

硅的施用通过与生长素和一氧化氮的相互作用减轻大麦的磷酸盐缺乏，促进生长、光合作用和氧化还原平衡，凸显了硅作为克服营养胁迫的肥料的潜力。

抽象的

据报道，硅（Si）可以减轻植物的营养胁迫，但关于施用硅对磷酸盐（Pi）缺乏下生长的植物的影响的研究仍然非常缺乏，特别是在大麦中。因此，本研究旨在研究 Si 在减轻大麦 Hordeum vulgare  L.（var. BH902）缺磷的不利影响方面的潜在作用。此外，还测试了两种关键的调节信号分子——生长素和一氧化氮（NO）——在大麦中硅诱导的对磷缺乏的耐受性中的参与情况。形态属性、光合参数、氧化应激标记（O ₂ ^·−、H ₂ O ₂和MDA）、抗氧化系统（酶促––APX、CAT、SOD、GR、DHAR、MDHAR 以及非酶促––AsA和 GSH）、NO 含量和脯氨酸代谢是不同处理下评估的关键性状。缺磷显着降低大麦幼苗的生长，这是由于氧化应激增强导致光合作用受到抑制。这些结果也与抗氧化活性（特别是 SOD 和 CAT）以及内源脯氨酸水平及其生物合成酶 (P5CS) 的增强同时发生。添加硅对在缺乏磷的培养基中生长的大麦植物表现出有益的影响，反映在通过调节抗氧化机制（特别是抗坏血酸-谷胱甘肽循环）增加生长、光合活性和氧化还原平衡。我们注意到，生长素和 NO 也被发现独立参与 Si 介导的 Pi 缺乏下大麦根的生长和其他参数的改善。磷酸转运蛋白 1 ( HvPHT1 )的基因表达分析数据表明，Si 有助于增加 Pi 的吸收，以满足 Pi 缺乏的大麦幼苗的需要，并且生长素和 NO 似乎都有助于 Si 完成这项任务，可能是通过诱导侧根形成。这些结果表明可以使用硅作为肥料来纠正植物营养胁迫的负面影响。进一步在基因水平上进行研究，了解硅诱导缓解缺磷的机制，有助于开发耐缺磷的新品种，特别是在缺磷土壤地区种植。