Investigation Of The Interaction Between PpDELLA And Transcription Factors Such As PpBZR In Peach

Peach(Prunus persica(L.)Batsch)belongs to Rosaceae Prunus and is an important fruit tree species in China.Peach have vigorous vegetative growth and large investment in orchard labor such as pruning and application of growth regulators.Dwarfing and close planting cultivation mode of peach trees can effectively resolve the difficulty.Previous studies showed that the content of endogenous GAs in Prunus persica Tenshouxing'(dwarf variety)was significantly higher than that in Prunus persica 'Qiumihong'(normal variety).We speculated that DELLA protein is accumulated in Fenshouxing,which inhibited branch elongation and promoted GA synthesis.Previous studies have indicated that DELLA proteins play their biological roles mainly in the way of protein interaction.For illuminating the regulatory functions of DELLA proteins on plant dwarfing,we mainly focused on the screening of the proteins which interacted with DELLA protein in this study.Qiumihong and Fenshouxing were selected as representative peach cultivar materials with different plant height in the study.The PpDELLA were identified from two cultivar and both of their protein contents in stem tip were analyzed by western blot.Besides that,the interaction between PpDELLA and several key transcription factors such as PpBZR(Key transcription factors in BR signaling pathway),PpARF6(Key transcription factors in Auxin signaling pathway)and PpPIF(Key transcription factors in light signaling pathway)were verified.Results showed that:(1)two members of PpDELLA were identified by bioinformatics method.Both of them possessed the conserved DELLA domain at N-terminal and GRAS domain at C-terminal.The phylogenetic tree indicated that PpDELLA1 and PpDELLA2 shared high similarity with AtGAI and AtRGA,respectively.(2)The results of Western blotting showed that the content of PpDELLA1 in stem tips of Fenshouxing was significantly higher than that of Qiumihong.It was difficult to detect PpDELLA1 in Qiumihong after treatment with GA3 for 3 h while there was no significant change in Fenshouxing,which suggested that the GA signaling pathway of Fenshouxing might be interrupted,and resulted in the accumulation of PpDELLA1 protein.(3)The nucleotide sequences of PpDELLA2 and PpDELLA2 were completely consistent,which implied that mutation of PpDELLA sequence is not related to dwarfingPhenotype of Fenshouxing.(4)Transcriptional self-activation trail showed that full-length CDS of PpDELLA 1 and PpDELLA2 had transcriptional self-activation while PpDELLA1D and PpDELLA2D in GRAS region had no this phenomenon.(5)The results of yeast two-hybrid showed that PpDELLA2 interacted with PpBZR1,PpARF6-2,PpPIF1,PpPIF1-1,PpPIF4 and PpPIF8 proteins.In conclusion,Fenshouxing is insensitive to GA and its dwarfing phenotype was resulted from the accumulation of PpDELLA.What's more,the accumulation of PpDELLA is not caused by the mutation of PpDELLA sequences.PpDELLA2 interacted with' PpBZR1,PpARF6-2 and PpPIFs.which implies that PpDELLA2might inhibit their biological functions by protein interaction and regulated multiple signal transduction pathways to cause peach dwarfing.