Search

The effects of putrescine on improving rice growth under aluminum (Al) toxicity conditions have been previously demonstrated, however, the underlying mechanism remains unclear. In this study, treatment with 50 μmol/L Al significantly decreased rice root growth and whole rice dry weight, inhibited Ca2+ uptake, decreased ATP synthesis, and increased Al, H2O2 and malondialdehyde (MDA) contents, whereas the application of putrescine mitigated these negative effects. Putrescine increased root growth and total dry weight of rice, reduced total Al content, decreased H2O2 and MDA contents by increasing antioxidant enzyme (superoxide dismutase, peroxidase, catalase and glutathione S-transferase) activities, increased Ca2+ uptake and energy production. Proteomic analyses using data-independent acquisition successfully identified 7 934 proteins, and 59 representative proteins exhibiting fold-change values higher than 1.5 were randomly selected. From the results of the proteomic and biochemical analyses, we found that putrescine significantly inhibited ethylene biosynthesis and phosphorus uptake in rice roots, increased pectin methylation, decreased pectin content and apoplastic Al deposition in rice roots. Putrescine also alleviated Al toxicity by repairing damaged DNA and increasing the proteins involved in maintaining plasma membrane integrity and normal cell proliferation. These findings improve our understanding of how putrescine affects the rice response to Al toxicity, which will facilitate further studies on environmental protection, crop safety, innovations in rice performance and real-world production.

Acid rain (AR) impacts forest health by leaching calcium (Ca) away from soils and plants. Ca is an essential element and participates in various plant physiological responses. In the present study, the protective role of exogenous Ca in alleviating AR stress in Liquidambar formosana Hance at the physiological and proteomic levels was examined. Our results showed that low Ca condition resulted in the chlorophyll content and photosynthesis decreasing significantly in L. formosana leaves; however, these effects could be reversed by high Ca supplementation. Further proteomic analyses successfully identified 81 differentially expressed proteins in AR-treated L. formosana under different Ca levels. In particular, some of the proteins are involved in primary metabolism, photosynthesis, energy production, antioxidant defense, transcription, and translation. Moreover, quantitative real time polymerase chain reaction (qRT-PCR) results indicated that low Ca significantly increased the expression level of the investigated Ca-related genes, which can be reversed by high Ca supplementation under AR stress. Further, Western blotting analysis revealed that exogenous Ca supply reduced AR damage by elevating the expression of proteins involved in the Calvin cycle, reactive oxygen species (ROS) scavenging system. These findings allowed us to better understand how woody plants respond to AR stress at various Ca levels and the protective role of exogenous Ca against AR stress in forest tree species.