The Analysis Of Response Difference Of Wheat Roots Under Boron Deficiency And Boron Toxicity By ITRAQ Quantitative Proteomics

Boron is an essential micronutrient element for plant growth.Boron deficiency or toxicity both affect plant growth.Wheat is one of the most important food crops in the world.Root is important for absorption of nutrients and water to wheat.However,there is no sufficient research on the molecular mechanism of boron deficiency or toxicity effects on growth of wheat roots.Three treatments(0?M H3BO3,0B;50?M H3BO3,50B;200?M H3BO3,200B)were used to clarify the different responses of wheat roots to boron deficiency or toxicity.The differences of morphology and physiological data of wheat root were investigated.iTRAQ quantitative proteomics techniques were used to compare the proteomic differences of wheat roots under different treatments.It was expected to provide academic support for the boron nutrient physiology of wheat.Germinated wheat seeds were treated with different boron concentrations for three days.It showed that root was very sensitive to boron concentration.Compared with 50 B,0B treatment induced shorter root,higher SOD activity,deeper O2.-staining,higher MDA content,and lower protein content.200 B treatment induced shorter root,deeper O2.-staining,and lighter H2O2 staining compared with 50 B.Above data showed that boron deficiency or boron toxicity led to root growth inhibition and superoxide anion accumulation in roots.In addition,there was no significant difference in root length under 0B or 200 B plus calcium treatment compared with boron alone,but the O2.-staining in the root all became deeper.Compared with 0B,there was no significant difference in root length under 0B plus nitrogen treatment,but the O2.-staining in roots became deeper and H2O2 staining became lighter.Compared with 50 B and 200 B,adding nitrogen induced shorter root,deeper O2.-staining and lighter H2O2 staining.It was proved that the short root and low protein content caused by boron deficiency or toxicity was not related to the absorption of nitrogen and calcium by roots.Wheat seedlings were treated with different boron concentrations for three weeks.Compared with 50 B,0B treatment induced lower active absorption area and active area ratio,higher total root absorption area,lower SOD activity,higher POD activity,and lower protein content.While compared with 50 B,200B induced shorter root,lower total root absorption area,active absorption area and active area ratio,SOD activity and protein content.It was speculated that there may be a relationship between the effect of treatment with boron deficiency and boron toxicity on the growth of wheat roots and the decrease of protein content.In order to analyze the effect of boron on the protein in wheat roots,the differential proteins identified by iTRAQ proteomics were used for the annotation and functional analysis of COG and KEGG respectively.The analysis of significant enrichment and analysis about the interaction of differential protein were also performed by using the STRING database.The results showed that there were 154 differential proteins that respond to boron and all were down-regulated compared with wheat treated with Boron deficiency.These differential proteins were mainly involved in secondary metabolism,glucose metabolism,signal transduction,replication,transcription,and posttranslational modification and other pathways.There were 249 differential proteins with specific response to boron deficiency,of which 248 were up-regulated and only 1 was down-regulated.These differential proteins mainly affect transcription such as nuclear RNA polymerase,DNA-directed RNA polymerase,RNA polymerase 14 k Da subunit,r RNA processing protein,r RNA precursor processing protein,DEA(D/H)-box RNA helicase Family proteins,t RNA dihydrouridine synthase,sugar metabolism such as sucrose phosphate synthase,?-fructofuranosidase,glyceraldehyde-3-phosphate dehydrogenase,nitrogen metabolism(urease),replication(ribonucleotide Adenylate reductase,replication factor C2),translation(ATP binding cassette subfamily,signal recognition microparticle subunit,30 S ribosomal S10)and redox function(aldehyde dehydrogenase,aldehyde reductase,neomenthol dehydrogenation)Enzymes,etc).It showed that wheat treated with boron deficiency may inhibit the growth of the wheat root mainly by affecting transcription and glucose metabolisminhibition.There were 242 differential proteins that specifically respond to boron toxicity,of which 80 were up-regulated and 162 were down-regulated.These differential proteins mainly affect the translation and processing of protein(such as ribosomal proteins,eukaryotic translation initiation factor 3C)calcium signals(such as calmodulin 6,calcium-dependent protein kinase,calcium binding proteins)and sugar metabolism(such as sucrose Enzymes,fructokinase,and peroxidases(such as peroxidase 30,peroxidase,peroxidase 12,etc.).Moreover,17 ribosomal proteins were the most concentrated in the protein interaction map and the interactions were very close.It was suggested that the Boron toxicity stress may inhibit the growth of wheat roots mainly by affecting the translation and processing of protein,glucose metabolism and calcium signal.To analyze the expression level of the selected differential proteins,we found that most of the protein expression levels are consistent with the iTRAQ data.In summary,this study analyzed the differences of protein in wheat roots treated with boron deficiency and boron toxicity using quantitative proteomics techniques and we find that the treatments with boron deficiency and boron toxicity cause the inhibition on the root growth in different ways.Boron deficiency treatment mainly affects transcription spliceosome and other metabolic pathways such as glucose metabolism.While boron toxicity treatment mainly affects the translation and processing of protein,glucose metabolism and calcium signal and other metabolic pathways.This study can provide data support for deep analysis of the molecular mechanism of boron stress,and provide help for the use of boron fertilizer in the filed.