Preliminary Study On Regulationship Of IQM2 Mediating Flowering And CaM Signaling In Arabidopsis

AtIQM2,encoded by At3G13600,is a calmodulin-binding protein?CaMBP?containing an IQ motif and invloved in autonomouse pathway flowering regulation.Flowering in time is very crucial for most plants to successfully survive and reproduct.And it is regulated by six closely interlinked but divergent genetic regulation pathways including photoperiod,vernalization,ambient temperature,gibberellin acid,autonomous and aging pathways.Both environmental and genetic factors can regulate flowering time in plants.Preliminary studies on IQM2 mediating calmodulin signal to regulate flowering and resistance to disease in Arabidopsis were conducted in this paper.The main results are as follows:1.LQ is the key amino acid residues in the IQ motif.Through IQ motif IQM2 in able to combine with CaM.The vectors harboring LQ-deleted iqrm2 were introduced into iqm2-2.Screened by antibiotics resistance,4 transformation lines were obtained.Among them,3 lines exhibited similar flowering time to wild type,meaning that IQM2 regulates flowering without mediation of CaM signaling.2.CML24 is a calmodulin-like protein and involves in photoperiod pathway flowering regulation.The double mutant cml24-4 iqm2-2 was constructed and identified.In long day condition,cml24-4 iqm2-2 flowered much later than either cml24-4 or iqm2-2,indicating that CML24 and IQM2 belong to different regulation pathways.This is constant with above result.3.Calmodulin signaling involves in regulation of response to disease in plants.Fluorescence parameters were measured in iqm2-2 and Ler after sprayed with Pst DC3000 for 7 days.Compared with initial value,the decline rate of quantum yield of Ler was more significant than iqm2-2.It can be postulated that IQM2 is involved in the process of reaction of plant to disease.However,the related mechanism remains to be studied.4.To clone the IQM2-combined proteins including CaM,P_35s:HA-IQM2 was introduced in iqm2-2,the homozygotes were identified and the proteins extrated from these lines were used to Western blotting hybridization.The results showed that IQM2 was detected in the transformed lines.Moreover,P_35s:HA,P_IQM2:HA and P_IQM2:HA-IQM2 were constructed,too.This facilitates to clone the IQM2-combined proteins including CaM.In summery,IQM2 is involved in autonomous pathway flowering regulation in Arabidopsis without mediation of CaM signaling,but is involved in the process of reaction of plant to disease.