Roles Of Actin Filaments Polymerization Gene TaARPs In Wheat Resistance Against The Stripe Rust Fungus

Microfilaments play an important role in plant intercellular signal transduction and material transport.Actin binding proteins participate in the dynamic arrangement of microfilaments such as polymerization and depolymerization.The research of the actin depolymerization has been studied deeply in recent years while the role of actin polymerization remains unknown.In this study,qRT-PCR and gene cloning method were used to anylasis relative expression of Arp2/3 complex.Microfilaments polymerization reagent was injected in the wheat leaves before inoculated with CYR31.To reveal the role of actin polymerization in the wheat against Puccinia striiformis f.sp.tritici(Pst.),the changes of the histology and the molecular-biology standard were observed.The main results are as follows:1.Four subunits of the Arp2/3 complex gene were cloned in wheat with completed open reading frame(ORF)named TaARP3,TaARPC3,TaARPC4 and TaARPC5.These subunits belonged to NBD-sugar-kinase-actin,P21-Arc,P20-Arc and P1 6-Arc superfamily in turn.Phylogeny tree analysis indicated that TaARPC5 and TaARP3 showed homology to Aegilops tauschii while TaARPC3 and TaARPC4 showed homology to Triticum urartu.Bioinformatics analysis found a transmembrane domain in TaARPC3.2.The expression of Arp2/3 complex in wheat-stripe rust fungus interaction was analyzed using qRT-PCR.The results showed there was a significant difference between the expressions of TaARPC1 in incompatible interaction and compatible interaction.The expression of TaARPC1 in incompatible interaction was up regulated especially at 72h and the expression was depressed after 18h in compatible interection.TaARPC3 had a highly relative rising at 24h and 48h.TaARPC4 was stable in wheat-stripe rust fungus interaction.The above results show that the TaARPC1 and TaARPC3 play an important role in wheat resistance against stripe rust fungus.3.The relative expression of Arp2/3 complex gene after ethylene,ABA,MeJA and SA treatments was detected.These results indicated that the up regulation of TaARP3 and TaARPC3 before 12 hours after ethylene treatment.ABA could depress the expression of these subunits especially the TaARPC3.SA could induce the expressions of TaARPC1 and TaARPC3 at the early age.TaARP3 and TaARPC3 may play a positive role in ethylene mediated signal transduction pathways.Arp2/3 complex take part in the response to biotic and abiotic stresses in wheat.4.The results of the histological observation showed that the accumulation of H2O2 moved in advance after injection with phalloidin.The ratio of H2O2 accumulation and HR occurrence increased significantly.The results suggest that the microfilaments polymerization play an important role in wheat resistance against stripe rust fungus.