The Function Of MxERF4 In Apple Rootstocks Under Stresses And It Might Be Controlled By MxMAPK6

Iron is a key nutrient for nearly all organisms since it functions as a component of many important enzymes and proteins participating in elementary biochemical activities.Iron deficiency can block the synthesis of chlorophyll precursors causing the leaf yellowing and diminishing the photosynthesis.Ethylene-responsive element-binding factors(ERFs)are proteins which bind to the cis-acting element known as the GCC box to activate the expression of functional genes drawn in responses to both abiotic and biotic stresses.ERF4 is a negatively-regulated transcription factor found in our laboratory which plays an important role in the iron deficiency response of apple rootstocks.In plants,mitogen-activated protein kinases(MAPKs)play vital roles in development and in a numerous of stress responses.In this research we cloned MPK6 and MPK4-2 and the results showed that MPK6 was highly expressed in roots of Malus xiaojinensis than in those of Malus baccata in case of iron paucity and the pictures of 3D of MPK6 displayed the same structures in those two cultivars.About ERFs,the 3D structure of ERF4 was same in Malus xioijinensis and Malus baccata.Two yeast hybrid system exposed an interaction between MPK6 and ERF4.The BiFC results confirmed that interaction.One yeast hybrid system disclosed that there is no relation between MPK6 promoters with ERF4.Outcomes from this investigation revealed that MPK6 could influence post-transcriptional regulation on ERF4 and also,they exposed that it has a vital role in helping Malus xiaojinensis to face the stress in case of iron scarcity.On the other hands,by using a series of gradient Fe treatments(low Fe,normal Fe and high Fe),WT and erf4 mutants were used to scrutinize the role of ERF4 in iron deficiency and salt stresses.Germination tryout results showed a greater salt tolerance at lower iron treatments than at higher iron treatments.Iron content had a significant function in resistance to salinity by crops.As ERF4 is a negative regulator,the absence of ERF4 results in better performance of the plants under low iron conditions,which in turn leads to improved salt tolerance.