Site-specific Phosphorylation Of Aquaporin PIP2;10 Coordinates Growth And Defense In Wheat

Food security is not only the foundation of mankind,but also the first priority of green and efficient agriculture.Wheat(Triticum aestivum)is the largest food crop in the world and the second largest food crop in China,with plays a significant role in China and global food security.Pathogen and insect attacks threaten crop yield and food security,the relationship between plant growth and defense response follow law of the mutual generation and restriction,which is the growth-defense tradeoffs that highly concerned by scientists.Plant immune response is usually accompanied by serious loss of growth and crop yield,if growth-defense tradeoff can be resolved,it's a good strategy to improvements of crop productivity and immunity traits.Recent research has found that eukaryotic aquaporins especially the plasma membrane intrinsic proteins,which are mediate the transports of many small molecule compounds substrates such as H2O,CO2,H2O2.Therefore,aquaporins involved in a variety of physiological processes such as plant growth and defense response.This study reports that TaPIP2;10 facilitates H2O2transports to cytoplasm activates PTI and PBD,which improve immunity in wheat.TaPIP2;10facilitates transports CO2 to enhance photosynthesis and regulates growth and grain yield in Wheat.Site-specific phosphorylation of TaPIP2;10 regulates transports H2O2 and CO2,overexpression of TaPIP2;10 simultaneously improve the immunity and grain yield in wheat.TaPIP2;10 transports H₂O₂ to activate PTI and PBD pathway against powdery mildew and aphid infestationIn order to identify PIPs that regulates growth and immunity in wheat,we first determined the expression of 18 TaPIPs in wheat inoculated with powdery mildew by q RT-PCR.The results showed that the up-regulated expression of TaPIP2;10 was the highest,which indicated that TaPIP2;10 was involved in the resistance of wheat to powdery mildew.To further investigate the biological functions of TaPIP2;10,we obtained TaPIP2;10 gene silencing plants and gene overexpression plants by BSMV-mediated gene silencing and gene overexpression system.The pathogenicity was identified by inoculated by B.graminis,the results showed that compared with wild-type plants,TaPIP2;10 overexpression causes 72%enhancements in wheat resistance to powdery mildew.The results suggested that TaPIP2;10 positively regulates the resistance of wheat to powdery mildew.To elucidate the mechanism of TaPIP2;10 regulates immunity in wheat,this study confirmed that TaPIP2;10 expression in yeast can transports H2O2 into yeast cells.Further studies confirmed that powdery mildew or flg22 treatment strongly induced produce H2O2 in wheat apoplast.TaPIP2;10 promote transports H2O2 into the wheat cytoplasm,which promoted callose deposition in wheat leaves,enhanced the phosphorylation level of MAPK,promoted the expression of PRs gene,and successfully activated the PTI pathway.We found that S.avenae prefers to feed and colonize on TaPIP2;10Si plants.The results indicated that TaPIP2;10 might regulate the resistance to aphid in wheat.Furthermore,rhodamine luminescence and electrical penetration graph(EPG)assays of aphid feeding on wheat leaves,the results showed that compared with wild-type plants,aphid feeds more phloem juice in TaPIP2;10Si,and TaPIP2;10 overexpression causes 60%enhancements in wheat resistance to aphid.The results suggested that TaPIP2;10 positively regulated the resistance of wheat to aphid.Further studies discovered that the outbreak of H2O2 in apoplast could also be induced by the aphid colonization and feeding of wheat,H2O2 was also transports into wheat cytoplasm mediated by TaPIP2;10,which induced the up-regulated expression of GSLs and phloem defense response(PBD)genes Hfr1 and Wci1,and significantly increased the callose deposition in wheat leaves,successfully activated the PBD pathway.Taken together,the results suggested that TaPIP2;10 mediated H2O2 transports to cytoplasm activate PTI and PBD pathways to against powdery mildew and aphid infestation.TaPIP2;10 transports CO₂ to enhance photosynthesis and increase wheat growth and grain yieldIn this study,we assessed whether TaPIP2;10 regulates wheat growth and development,detection of wheat growth phenotype in the plant growth chamber.The results showed that compared with wild-type plants,the plant height was significantly decreased by TaPIP2;10Si.It's indicated that TaPIP2;10 is closely related to growth and development in wheat.We further analyzed the growth phenotype and counted the grain yield in wheat,the results showed that compared with wild-type plants,TaPIP2;10OE significantly increased wheat biomass,grain number per heads and 100-seed weight,finally increased grain yield by 22%.However,the biomass,grain number per heads and 100-seed weight of TaPIP2;10Si decreased significantly,and the yield decreased by 25%.The results suggested that TaPIP2;10 positively regulated the wheat growth development and grain yield.Photosynthesis is the basis of plant growth and the decisive factor of productivity,which finally contributes to the process of plant storage of energy and matter.To elucidate the mechanism of TaPIP2;10 regulates wheat growth and grain yield,we analyzed the effects of TaPIP2;10 silencing or overexpression on photosynthesis by photosynthesis analysis system.The results showed that compared with wild-type plants,TaPIP2;10OE increased AN and gm by 41%and 40%.On the other hand,AN and gm significantly reduced by TaPIP2;10Si.Taken together,TaPIP2;10 was characterized as a physiologically relevant CO2-transporting facilitator,TaPIP2;10 facilitates transports CO2 to enhance photosynthesis improve wheat growth and grain yield.Site-specific phosphorylation of TaPIP2;10 enhances growth and defense in wheatAQPs substrate transport pathway is regulated by gating and trafficking,which is the key functional mechanism of AQPs.Phosphorylation modification is very important for the function of PIP,we predict that phosphorylation of TaPIP2;10 also affects the substrate transport function.In this study,TaPIP2;10 and it's predicted serine sites were site-directed mutagenesis to dephosphorylation mutants or phosphomimic mutants,which were overexpressed in yeast and wheat,respectively.It was confirmed that H2O2 treatment could activated phosphorylation of TaPIP2;10 and S121A mutation could inhibits TaPIP2;10 phosphorylation,which indicated that Ser121 is closely associated with TaPIP2;10-mediated H2O2 transmembrane transport.Furthermore,it was confirmed that overexpression of TaPIP2;10 S121D could significantly enhanced its transport ability for H2O2.It was confirmed that apoplast H2O2 induced by infection of powdery mildew and aphid,which could also activate TaPIP2;10 phosphorylation.TaPIP2;10 S121A mutation also inhibited its phosphorylation,and restricted the H2O2 transports to wheat cytoplasm,which inhibited the activation of PTI and PBD.This results suggests that the phosphorylation of S121 of TaPIP2;10 play a key role in transports H2O2 to cytoplasm and activating PTI and PBD pathways.We also investigated the phosphorylation of TaPIP2;10whether effect of transports CO2.In our study,we found that the increase of atmospheric CO2concentration,when the intercellular CO2 concentrations(Ci)reached to 800?M/M air,which strongly induced phosphorylation of TaPIP2;10,but S280A mutation inhibited CO2 induced TaPIP2;10 phosphorylation,which indicated that Ser280 was essential for TaPIP2;10 transports CO2.It was also found that overexpression of TaPIP2;10 S280D increased the grain yield compared to TaPIP2;10OE,and overexpression of TaPIP2;10 S121D significantly improve immunity in wheat.Taken together,site-specific phosphorylation of TaPIP2;10 enhances growth and defense in wheat.In summary,we report that the wheat aquaporin TaPIP2;10 relies on site-specific phosphorylation to support wheat productivity and immunity.In response to the apoplastic H2O2 induced by pathogen or insect attack,TaPIP2;10 is phosphorylated at S121 to transports this H2O2 into the cytoplasm activate PTI and PBD pathways to restrict further attacks.In response to elevated atmosphere CO2 concentrations,TaPIP2;10 is phosphorylated at the serine residue S280 to transports CO2 into wheat cells,thereby enhancing photosynthesis with an outcome of grain yield increase.Wheat resistance and grain yield can be increased by TaPIP2;10 overexpression.This study will provide an important basis for balancing growth-defense tradeoffs to improve productivity and immunity in agriculturally crops.