Proteomics Research Of Vegetative Growth Advantage In Allotriploid Populus Spp.(Section Tacamahaca)

Populus is an important afforesting tree in China,so it has great theoretical value and practical guidance to carry out research on the mechanism of vegetative growth advantage in Populus allotriploid.In the present study,a newly synthesized F1 hybrid diploid and two allotriploid populations driven by 2n female gametes[FDR(First division restitution),SDR(Second division restitution)],and their common parents were used.The proteomics expression difference between the allotriploid and their parents were investigated by iTRAQ-based approach and Label-free proteome quantitative method were used to analyze the proteomics divergence between allotriploid and diploid with the same parents in the different leaf positions.We explored the characteristics and regulation of protein expression in Populus allotriploids and illustrate the proteomic basis of vegetative growth advantage in Populus allotriploid preliminarily.The main results were as follows:(1)Compared with their parents Zheyin3#and BJY,the number of differentially expressed proteins at 5th leave position between FDR allopolyploids and their parents were 49 and 161,respectively,and SDR allopolyploids was 54 and 98,respectively.The biological function analysis indicated that the DEPs between the allotriploid and their parents were mainly involved in protein and amino acid synthesis,photosynthesis,carbohydrate metabolism,substance transport and signal transduction.In addition,when compared with Populus diploid,47 and 30 proteins were differently expressed in FDR allotriploid and SDR allotriploid at 5th leave position.These DEPs are mainly enriched in TCA cycle,protein synthesis and stress response.(2)The proteomics expression of allotriploids displayed parental expression level dominance(ELD).78.7%and 58.7%of DEPs in FDR and SDR showed parental expression level dominance,indicated an expression bias toward the female parent.The parental ELD proteins included 22 chloroplast proteins(such as PSII cytochrome b559,cytochrome f,RuBisCO,etc),13 ribosomal proteins,5 DNA binding family proteins and 4 sucrose and starch synthesis proteins.The parental ELD may be related to chromosomes doubling of female gamete.(3)The DEPs of leave positions with different types allotriploid showed similar expression pattern.417 proteins were differently expressed between allotriploid and diploid on the higher photosynthesis and fast-growing plant type.While there were 287 DEPs between the allotriploid and diploid in the lower photosynthesis and fast-growing plant type.Proteins differently expressed between allotriploid and diploid in lower compared to higher photosynthetic and fast-growing type plant were almost the same,but there are little differences in fold-change of some proteins.The DEPs were mainly related to ribosome structure,starch and sucrose metabolism,TCA cycle,glycolysis/gluconeogenesis and stress response.In addition,169 DEPs were detected between fast-growing plant of low photosynthesis and fast-growing plant of high photosynthesis,which were mainly enriched in ribosome,starch and sucrose metabolism,carbon metabolism,amino sugar and nucleotide sugar metabolism,stress response and photosynthesis.(4)Proteomics details demonstrated a different expression pattern among three leaf positions(5th,10th,and 25th).With leaf position from up to down,most proteins related to TCA cycle,amino acid and carbohydrate metabolism increase gradually,and photosynthesis-related proteins show a trend of increasing first and then decreasing.Proteins associated to plant resistance mainly decreased first and then increased,while have a relative high expression level at 25th leaf position.In addition,the high expression level of proteins related to resistance(glutathione transferase,peroxidase,dehydrin family protein,PERK4,and HSP70)in the 25th leaf position may delayed the leaves senescence and enhanced the resistance of allotriploid.(5)We found big differences in protein expression pattern of photosynthesis between allotriploid and diploid in Populus.The allotriploid expression level of proteins in photosystem I(PsaE,PsaL,and F type ATPases ? and ? subunits),photosystem ?(PsbQ,PsbR,PsbP,and FNR),light-harvesting protein complexes(Lhca2 and Lhca6)and photosynthetic carbon fixation(FBA and PPDK)were significantly higher than diploids.But the expression of three proteins related to photosynthesis,including OEE1,Lhca5 and MDH1,decreased in allotriploid.(6)Populus allotriploids may have faster carbohydrate synthesis and energy metabolism efficiency.Compared to the diploids,7 enzymes related to starch and sucrose metabolism(GBSS-I,glgC,SSS,PGM,UGP2,SS and polysaccharide phosphorylase)were significantly up-regulated in Populus allotriploids,only MGAM down-regulated in Populus allotriploids.This may suggests that the allotriploid have a faster carbohydrate synthesis efficiency.In addition,6 proteins related to TCA cycle(OGDH,ACO,IDH1,FBA,GLDC,and PPS)significantly up-related in allotriploid,while HIBCH and MDH1 down-regulated.Furthermore,11 protrins involved in respiratory chain(NDUFV2,NDUFAB1,ATFAOA,ATFAOB,ATPaFIG,ATPaF1E,ATTaVOC and ATTeV1F)significantly up-regulated in allotriploid,but the expression level of Ndufa8,Ndufb10 and ATTaF1B decreased.In conclusion,the increased abundance of photosynthetic proteins,enzymes of starch and sucrose metabolism,oxidative phosphorylation respiratory chain assembly proteins and TCA cycle enzymes might promoted the accumulation of carbonhydrate and increased energy metabolism efficiency in allotriploid.In addition,the relative high expression level of stress response proteins at the 25th leaf position may enhanced the leaf resistance and delayed the leaves senescence in allotriploid.These findings above may result vegetative growth advantage in Populus allotriploid.