National Key Lab for Germplasm Innovation and Utilization of Horticultural Crops, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, No. 1 Shizishan Street, Wuhan 430070, Hubei, PR China.
School of Horticulture and Landscape Architecture, Yangzhou University, 88 South Daxue road, Yangzhou, 225009, Jiangsu, PR China.
Tree Physiol. 2024 Sep 3;44(9). doi: 10.1093/treephys/tpae098.
Manganese (Mn) is indispensable for plant growth, but its excessive uptake in acidic soils leads to toxicity, hampering food safety. Phosphorus (P) application is known to mitigate Mn toxicity, yet the underlying molecular mechanism remains elusive. Here, we conducted physiological and transcriptomic analyses of peach roots response to P supply under Mn toxicity. Manganese treatment disrupted root architecture and caused ultrastructural damage due to oxidative injury. Notably, P application ameliorated the detrimental effects and improved the damaged roots by preventing the shrinkage of cortical cells, epidermis and endodermis, as well as reducing the accumulation of reactive oxygen species (ROS). Transcriptomic analysis revealed the differentially expressed genes enriched in phenylpropanoid biosynthesis, cysteine, methionine and glutathione metabolism under Mn and P treatments. Phosphorus application upregulated the transcripts and activities of core enzymes crucial for lignin biosynthesis, enhancing cell wall integrity. Furthermore, P treatment activated ascorbate-glutathione cycle, augmenting ROS detoxification. Additionally, under Mn toxicity, P application downregulated Mn uptake transporter while enhancing vacuolar sequestration transporter transcripts, reducing Mn uptake and facilitating vacuolar storage. Collectively, P application prevents Mn accumulation in roots by modulating Mn transporters, bolstering lignin biosynthesis and attenuating oxidative stress, thereby improving root growth under Mn toxicity. Our findings provide novel insights into the mechanism of P-mediated alleviation of Mn stress and strategies for managing metal toxicity in peach orchards.
锰（Mn）是植物生长所必需的，但在酸性土壤中过量吸收会导致毒性，从而危及食品安全。已知施用磷（P）可以减轻 Mn 毒性，但其中的分子机制仍不清楚。在这里，我们对 Mn 毒性下桃根对 P 供应的反应进行了生理和转录组分析。Mn 处理破坏了根的结构，并由于氧化损伤而导致超微结构损伤。值得注意的是，P 处理通过防止皮层细胞、表皮和内皮层的收缩，以及减少活性氧（ROS）的积累，改善了受损的根，从而减轻了有害影响。转录组分析显示，在 Mn 和 P 处理下，苯丙烷生物合成、半胱氨酸、蛋氨酸和谷胱甘肽代谢相关的差异表达基因富集。P 处理上调了木质素生物合成核心酶的转录物和活性，增强了细胞壁的完整性。此外，P 处理激活了抗坏血酸-谷胱甘肽循环，增强了 ROS 解毒。此外，在 Mn 毒性下，P 处理下调了 Mn 吸收转运蛋白，同时增强了液泡隔离转运蛋白的转录物，减少了 Mn 的吸收并促进了液泡储存。总的来说，P 处理通过调节 Mn 转运蛋白、增强木质素生物合成和减轻氧化应激，防止 Mn 在根中积累，从而改善 Mn 毒性下的根生长。我们的发现为 P 介导减轻 Mn 胁迫的机制以及在桃园管理金属毒性的策略提供了新的见解。
