Mechanism Of Brassinosteroid In Response To High Manganese Stress In Plant

Manganese(Mn)is one of the indispensable trace elements in plants,both deficiency and excess of which will seriously caused the depression of growth and development.The absorption and utilization of Mn are coordinated by various plant hormones.Brassinosteroids(BRs),a class of phytosteroids that play important roles in multiple processes required for normal plant growth and development and various stress responses..However,the mechanism by which BR regulates Mn uptake is still unclear.This paper focused on the mechanism of BR regulating manganese response by soybean phenotype observation,ion omics analysis and transcriptome analysis.The main conclusions are listed as follows:(1)The growth of hypocotyls and roots of soybean was significantly inhibited by Propiconazole(PPZ),a BR biosynthesis inhibitor,in a dose-dependent way.Hypocotyl length,primary root length,lateral root length and number decreased compared with mock treatment.PPZ treatment also caused significant reduction of manganese in the shoot but not root part.(2)Gradient e BL treatment decreased the length of primary root length and lateral root length in soybean.However,e BL treatment decreased the hypocotyl length at 10 n M,but increased that at 1 ?M.The Mn content was decreased by 10 n M and 1 ?M e BR treatment in the root.(3)Long-term treatment with high Mn resulted in yellow and brown spots on the soybean leaves.Further ion omics analysis showed that the concentration of Mn and Zn increased significantly in the shoot part.Meantime,there was a significant increase in Mn,Fe,and Al in the shoot,but a significant decrease in Mg.(4)High Mn significantly inhibited primary root length and root hair development in Arabidopsis.Interestingly,PPZ treatment repressed this inhibition by high manganese.Consistently,BR insensitive mutant bri1-5 was less sensitive to this primary root length inhibition caused by high Mn.Furthermore,transcription levels of NRAMP1 and MTP11 were significantly increased in bri1-5 mutant.High Mn treatment reduced BZR1 protein level in an over-expression line.(5)RNA-seq was performed to uncover the transcriptome profiles by BR and high Mn treatment.8164 down-regulated genes and 8249 up-regulated genes were found after BR treatment,while 8215 up-regulated genes and 7468 down-regulated genes after PPZ treatment.8369 up-regulated genes and 7744 down-regulated genes were sorted out in the high manganese treated group.1081 genes were found to be regulated by BR,PPZ and high Mn treatment.GO enrichment analysis revealed that photosynthesis,light harvesting in photosystem I and photosystem II stabilization related genes were enriched in these genes.PPZ and high-Mn coregulated 1781 genes were most involved in hydrogen peroxide catabolic process,sulfate reduction,abscisic acid activation and other signaling pathways.BR and HMn co-regulated 1561 genes,mainly regulating the regulation of stomatal closure,oxalic acid metabolism and lignin catabolism and other processes.To sum up,here we explored the regulation mechanism of BR and manganese response in soybean and Arabidopsis,analyzed the phenotype of gradient-treated plants,and used RNA-seq technology to explore the co-regulated genes of manganese and BR and gene function analysis.Through these analyses,this project will provide experimental basis for further analysis of the molecular mechanism how BR regulates high manganese response.Our work will help to solve the problems of crop yield and safety caused by manganese toxicity...