Study On The Mechanism Of The Mediation Of Jasmanate Signal Transduction Of IQM1 In Arabidopsis

IQM1(AT4G33050)belongs to the IQM family and is a CaM-binding proteins(CaMBPs)with an IQ motif.Previous studies have found that IQM1 may mediate JA Signaling through regulating JAZ and participate in plant disease resistance.In this paper,the location of IQM1 in JA Signaling is further determined,and the mechanism of IQM1 mediated JA signaling was also explored.The main results are as follows:1.The resistance of the mutant iqm1-1 to the Pst DC3000 was stronger than the wild type Col;the disease resistance of the double mutant iqm1-1 myc2-2 was basically consistent with myc2-2,and was stronger than Col and iqm1-1;the disease resistance of iqm1-1 coi1-2 was basically consistent with coi1-2,and was obviously stronger than the other genotypes.2.Expression level of Jasmonate ZIM-domain(JAZ)genes,which are key negative regulators of JA signaling,were analysed through RT-qPCR.Results show that the expression of JAZ1 gene in iqm1-1 was down regulated compared with wild-type Col;JAZ1 gene in double mutant iqm1-1 JAZ1-GUSOE was also significantly down regulated compared with JAZ1 overexpression lines(JAZ1-GUSOE).3.Under water treatment,the activity of GUS in the double mutant iqm1-1JAZ1-GUSOE seedlings was almost not detecded,meaing that the content of JAZ1-GUS fusion protein was almost 0;GUS activity in JAZ1-GUSOE seedlings was enhanced with 26 S proteasome inhibitor MG132,but the GUS activity in the iqm1-1JAZ1-GUSOE seedlings remained unchanged.4.The resistance of the mutant JAZ1-GUSOE to the Pst DC3000 was basically consistent with iqm1-1 JAZ1-GUSOE.From all aspects,the degree of disease was significantly lower than iqm1-1 and Col.5.After sprayed with Pst DC3000 for 0 hour,1 hour,3 hour,the stomata of Col,iqm1-1,JAZ1-GUSOE and iqm1-1 JAZ1-GUSOE 4 genotype plants do not show any significant difference and regularity changes.6.The samples obtained from RIP were reverse transcribed into cDNA and sentto the company for sequencing.According to the sequencing results,4 candidate target genes were obtained.The specific bands were amplified by the primers of AT3G41768(encoded rRNA)and ATCG00020(encoded PHOTOSYSTEM II REACTION CENTER PROTEIN A,PSBA)after PCR verification.The above results indicate that IQM1 mediates Jasmonate signaling and involves in plant disease resistance depends on MYC2 or COI1 and may not be through direct regulation of JAZ1.IQM1 protein may have the ability to bind rRNA or RNA encoding PSBA.