Study On The Differences Of Blueberry And Wufanshu Plants In Response To PH And The Effects Of Arbuscular Mycorrhizae On Blueberry

In recent years,blueberry（Vaccinium spp.）industry in China has developed rapidly,and become the new fruits in many provinces.However,the cultivation of blueberry has still influenced by many factors,such as pH value in matrix,which is one of the major factors restricting the development of blueberry.In this study,using a pot of sand culture and soil culture methods,taking‘Wufanshu’（Vaccinium bracteatum Thunb.）,rabbiteye blueberry（Vaccinium ashei Read.）cv.‘Brightwell’plants and southern highbush blueberry（Vaccinium corymbosum）‘O’Neal’as the experimental material,we investigated the physiological reaction between‘Wufanshu’and blueberries in response to different pH values,and the effect of arbuscular mycorrhizal（AM）fungi on blueberry and its physiological mechanism in different pH values.To evaluate the effects of different pH values such as 4.2,5.2 and 6.2,on the growth and relative physiological indices of‘Wufanshu’and rabbiteye blueberry cv.‘Brightwell’plants.The results showed that the biomass,chlorophyll content and root activity of‘Wufanshu’and blueberry were the lowest at pH 6.2 level,the highest of biomass and root activity in‘Wufanshu’and blueberry were found at pH 5.2 and 4.2levels,respectively.The soluble sugar and protein contents of‘Wufanshu’and blueberry were the highest at pH 6.2,the lowest of them were detected at pH 5.2 and4.2,respectively.Phosphorus（P）,iron（Fe）and zinc（Zn）in each position of‘Wufanshu’at pH 5.2 level,and P and Fe in roots,Fe in stems,and Fe and Zn in leaves of blueberry at pH 4.2 level,were relatively high.Activities of peroxidase（POD）and catalase（CAT）,and malondialdehyde（MDA）content of‘Wufanshu’and blueberry were the highest at pH 6.2 level,while the lowest of them were presented at pH 5.2 and 4.2,respectively.These results indicate that 5.2 and 4.2 are the optimal pH values for the growth of‘Wufanshu’and blueberry plants,respectively,and the growth of both,especially blueberry,were inhibited at pH 6.2 level.Physiological reaction of AM fungi Glomus mosseae inoculation on the southern highbush blueberry’O’Neal’was investigated in different pH values（4.2 and 6.2）.The results showed that,in different pH values,AM inoculation treatment increased the biomass,chlorophyll and carotenoid content,net photosynthetic rate,transpiration rate,stomatal conductance,intercellular CO₂ concentration,as well as Fv/Fm（maximum energy conversion efficiency of PSII）,Fv’/Fm’（the effective quantum yield of PSII photochemistry）,Fs（fluorescence）,qP（photochemical quenching）,Fm（maximal fluorescence yield）,Fo’（minimum fluorescence light）,Fm’（maximum fluorescence light）,and qN（non photochemical quenching）.However,leaf superoxide anion production rate,hydrogen peroxide content,Fo（initial fluorescence）,and NPQ（non photochemical quenching）were decreased by AM inoculation.The results showed that AM fungi inoculation increased the photosynthesis,fluorescence and antioxidant capacity of blueberry,leading to improvement of the adaptability of blueberry’O’Neal’in response to different pH values.Using RNA-Seq technique,the effects of AM fungi inoculation on the gene expression of’O’Neal’blueberry leaves were studied under different pH values（4.2and 6.2）.There existed only 5 of the differentially expressed genes between the pH4.2 and pH 6.2 treatments under AM fungi inoculation,but none of the five genes were annotated.In the absence of AM fungi,there were 20 differentially expressed genes between the pH 6.2 and the control（pH 4.2）,and 16 genes were up-regulated,and 4 genes were down regulated.These genes mainly involved in the ethylene synthesis,fatty acid oxidation,photorespiration,aerobic respiration,GSH-mediated detoxification,eugenol and isoeugenol synthesis pathway,etc.Under the pH 6.2condition,there were 3312 differentially expressed genes between AM inoculation and non-AM inoculation.253 genes were annotated,and they mainly involved in IAA metabolism,light reaction,etc.Compared with the control（pH 4.2）,there existed 43 differentially expressed genes among the treatments of AM inoculation,pH6.2,and AM inoculation under pH 6.2 condition,and the change of these genes was similar,most genes were up-regulated,and a few genes were down-regulated.These mainly involved in aerobic respiration,photorespiration,and ethylene synthesis pathways.Thus,hormone and photosynthesis metabolisms were closely related to the improvement of blueberry in response to pH values by AM fungi inoculation.