Auxin and brassinosteroids (BRs) are two major growth-promoting phytohormones that shape hypocotyl elongation; however, the cross-talk between auxin and BR in this process is not fully understood. In this study, we found that auxin-induced hypocotyl elongation is dependent on brassinazole-resistant 1 (BZR1), a core BR signaling component. Auxin promotes BZR1 nuclear accumulation in hypocotyl cells, a process dependent on mitogen-activated protein kinase 3 (MPK3) and MPK6, which are both activated by auxin and whose encoding genes are highly expressed in hypocotyls. We determined that MPK3/MPK6 phosphorylate and reduce the protein stability of general regulatory factor 4 (GRF4), a member of the 14-3-3 family of proteins that retain BZR1 in the cytoplasm. In summary, this study reveals the molecular mechanism by which auxin promotes hypocotyl elongation by enhancing BZR1 nuclear accumulation via MPK3/MPK6-regulated GRF4 protein stability.
Polycyclic aromatic hydrocarbons (PAHs) constitute a category of persistent organic contaminants that possess the potential to induce carcinogenic, teratogenic, and mutagenic consequences. Our previous findings have revealed that plant roots actively take up PAHs through co-transport with protons, and auxin can promote PAHs uptake by wheat roots. It remains unclear whether nitric oxide (NO), a signaling molecule involved in numerous physiological processes in plants and downstream of auxin, can affect PAHs uptake by plant roots. In our study, 50 μmol/L sodium nitroprusside (SNP) significantly enhanced phenanthrene uptake after 4 h of exposure. After the addition of SNP (50 μmol/L), the H + flux on root surface increased, and H + -ATPase activity was activated, indicating that exogenous NO promotes phenanthrene uptake by plant roots via activating H + -ATPase. By studying the effects of 50 μmol/L cyclic guanosine monophosphate (cGMP), 5 mmol/L Ca 2+ , and 50 μmol/L adenosine monophosphate (AMP) on phenanthrene uptake by ryegrass roots and measuring root calcium-dependent protein kinases (CDPK) activity, we demonstrated that exogenous NO promotes phenanthrene uptake through the signaling pathway of NO, cGMP, Ca 2+ , CDPK, 14-3-3 protein and H + -ATPase. The results contribute significant insights into elucidating the underlying mechanisms of NO modulating PAHs absorption by plant roots, thereby offering crucial strategies for advancing food safety measures and enhancing the phytoremediation potential of soils and waters contaminated with PAHs.
Considering of the possible application of fatty acids secretion in industrial production process for reducing extraction costs, the effects of enhanced fatty acids secretion by knocking out acyl-CoA synthetases on the global regulation, cellular metabolism were investigated through integrated omics analysis. Firstly, functional category analysis of differential expression genes showed that most of the genes were associated with the cell cycle and biology process such as cellular component biogenesis, cell wall organization and so on. Secondly, the decreased mRNA levels of Tdh, Eno and Pgk1 in glycolysis in faa mutant YB526 were confirmed by the differential protein analysis. As described in previous reports, the decreased protein levels of Tdh, Eno and Pgk1 were resulted from the increase of 14-3-3 protein activity. However, the increased level of 14-3-3 proteins could not improve the biosynthesis of ergosterol in the acyl-CoA deficiency strain YB526 due to the toxic effects of fatty acids. Thirdly, the decrease of ergosterol and ceramide contents in cell envelopes can improve the permeation of membrane and fatty acids secretion in faa mutant YB526. This comprehensive omics analysis could be helpful in the rational design of robust yeasts for the production of free fatty acids or other biobased chemicals.
危险品化学品经营许可证（带存储）