Root Microbial Differential Analysis And Potential Benificial Bacteria Screening In Trifoliata Orange(Poncirus Trifoliata L.Raf.) And Zhique(Citrus Wilsonii Tanaka) Planted In Alkaline Soil

Cultivated citrus is grafted with rootstock and scion.Trifoliate orange(Poncirus trifoliata L.Raf.),the most commonly used rootstock,is sensitive to iron deficiency and thus not suitable for c?ltivation in alkaline soils.Our previous study found that Miyagawa Wase Satsuma mandarin(Citrus unshiu Marc.)grafted on Zhique(Citrus wilsonii Tanaka)citrus rootstock from Chenggu couty of Shaanxi provience showed tolerance to iron deficiency under calcareous soil condition.Further study confirmed that Zhique(Citrus wilsonii Tanaka)citrus rootstock has a strong resistance to iron deficiency and co?ld be used as an ideal Fe-deficiency-tolerant rootstock for citrus c?ltivation in calcareous soils.Plants evolved several strategies to enhance Fe acquisition,while soil microorganism also play a critical role in plant Fe acquisition.In this study,the Fe-deficiency-tolerant rootstock Zhique and Fe-deficiency-sensitive rootstock trifoliate orange were used as samples.The soils used in the experiments were came from the Chenggu couty citrus producing area of Shaanxi provience.The effects of soil sterilization on iron acquisition of Zhique and Trifoliate orange was investigated through the alkaline soil pot experiment.A comparative analysis of the microbial communities of citrus roots and rhizosphere soil between Zhique and Trifoliata orange was performed through 16 s rRNA high-throughput sequencing technology.The bacterial dilution plate c?lture method was used to screen the beneficial bacteria promoting iron acquisition in citrus.We are trying to explore the relationship between microorganism and iron acquisition of Zhique and Trifoliate orange.The main res?lts are as follows:1.The differences of iron acquisition of Zhique and Trifoliate orange under sterilized and non-sterilized conditions.To reveal the effects of the soil microorganisms on the iron acquisition of Zhique and Trifoliate orange,the soil was sterilized or non-sterilized for experiment.Res?lts revealed that Zhique showed a strong tolerance to iron deficiency,and no iron chlorosis was observed regardless of sterilization or no.However,soil sterilization treatment significantly reduced the total iron content of the root of Trifoliate orange,and the iron chlorosis appeared in advance.The res?lt further proved that as compared with Trifoliate orange,Zhique has a strong resistance to iron deficiency.Soil sterilization affected iron acquisition of the two rootstocks to some extent.2.The differences of root microbial community between Zhique and Trifoliate orange.Root microbial community in Zhique and Trifoliate orange rootstocks and its difference was compared by 16 s rRNA high-throughput sequencing technology.Res?lts revealed that the bacterial abundance in rhizosphere soil samples was significantly higher than that in root samples in both genotypes.The bacterial diversity of Zhique(Citrus wilsonii Tanaka)samples was comparable to that of Trifoliata orange(Poncirus trifoliata L.Raf.)samples.The main bacterial groups were belonged to Proteobacteria and Actinobacteria,and the abundance of 16 genera bacterial showed significant difference between two genotypes,of which 11 were more abundant in Zhique(Citrus wilsonii Tanaka)than Trifoliata orange(Poncirus trifoliata L.Raf.),and the remaining 5 were more abundant in Trifoliata orange.It is notable that the bacterial producing siderophores,rhizobials,mineral weathering bacteria and saline tolerance bacterial were more abundant in Zhique(Citrus wilsonii Tanaka)than in Trifoliata orange(Poncirus trifoliata L.Raf.),suggesting that these bacteria might play important roles in iron acquisition of Zhique(Citrus wilsonii Tanaka).3.The screening of potential probiotics promoting citrus iron acquisition.Through the bacterial dilution plate c?lture method,the differentiated bacteria were identified and saved for the inoc?lation test.Res?lts revealed that Pseudomonas is the dominant rhizosphere microorganism in Zhique and Trifoliate orange.Pseudomonas moorei and Pseudomonas plecoglossicida were only detected in Zhique,Pseudomonas pseudoalcaligenes co?ld be deceted in both rootstocks.The rhizosphere microorganism Pseudomonas co?ld alleviate the iron chlorosis symptom of Trifoliate orange in sterilized soils.This study provides a basis future research on the iron acqusition mechanism of citrus rootstocks and wo?ld faciliate the development of microbial fertilizers.