Differences In Phyllosphere Microbial Communities Structure Between Female And Male Populus Cathayana

There are a large number of bacteria,fungi and other microorganisms on the phyllosphere of plants,which participate in the physiological metabolism of plants by interacting with the plant host.Phyllosphere microorganisms play an important role in the global carbon and nitrogen cycle,whose relationships with plant hosts are very complex.Phyllosphere microorganisms can interact with their host plant through nitrogen fixation,plant growth promotion,plant stress resistance enhancement,alteration of plant surface characteristics,or pesticide residues degradation.Different plants could select and sharp unique phyllosphere microbiota for their unique phyllosphere environment.However,most of the current studies have focused on the study of the phyllosphere microorganisms of monoecious plants,but little is known on the phyllosphere microorganisms of dioecious plants.As a typical dioecious plant in temperate zone,Populus cathayana is widely distributed in north China,which is also an important forest resource tree species in China.Previous studies have shown that significant differences in morphological characteristics and physiological metabolism between female and male P.cathayana were detected.In this study,the common native dioecious species P.cathayana,in the Xiaowutai Mountain Nature Reserve,Hebei Province,China,was chosen to characterize and compare the diversity and composition of phyllosphere bacteria and fungi communities between females and males using 16 S rRNA/ITS1 gene-based MiSeq sequencing.The dominant factors affecting the differentiation of the phyllosphere microbial community composition between female and male P.cathayana were revealed.The main findings are as follows:1.The sequencing results showed that 8 phylum,17 classes,31 orders,51 families and 90 genera were identified in the bacterial communities of P.cathayana phyllosphere,and 3 phylum,21 classes,51 orders,80 families and 118 genera were identified in the fungal communities of P.cathayana phyllosphere.2.The Alpha diversity indexes(Chao1,Shannon and Pd indexes)of phyllosphere bacterial and fungal communities between females and males showed no significant difference(P>0.05).However,the Pd index of phyllosphere bacterial communities showed significantly different between three altitudes.The Pd index at high altitude was the lowest(P<0.05).3.The community structure showed that Proteobacteria(91.93%)and Bacteroidetes(3.68%)were the dominant phyla in the phyllosphere bacteria community of P.cathayana phyllosphere.At the genus level,Hymenobacter(12.23%),Sphingomonas(15.16%)and Methylobacterium(15.12%)were the dominant bacteria genera in P.cathayana phyllosphere.Ascomycota(91.13%)and Basidiomycota(8.79%)were the dominant fungal phyla in P.cathayana phyllosphere.At the genus level,Zymoseptoria(40.19%,Venturia(16.23%)and Phoma(13.05%)were the dominant fungal genera in P.cathayana phyllosphere.4.By comparing the composition of the phyllosphere microbial community of the female and male of the P.cathayana,it was found that both female and male P.cathayana had their unique phyllosphere bacteria and fungi microbiota.At the relative abundance level of >0.01%,bacteria Rhodococcus(0.09%),Devosia(0.07%)and fungi Pringsheimia(0.09%)were only detected in female phyllosphere,whereas Bradyrhizobium(0.05%)was only present in male phyllosphere.5.Significant differences in the relative abundance of bacterial and fungal genera were detected between sexes at different altitudes using Metastats analysis.Different microbial genera were enriched in the female and male phyllosphere of P.cathayana,respectively.The relative abundance of the phyllosphere bacteria Amnibacterium and fungi Aureobasidium,Phoma,Monilinia,Rhodotorula,Fusicladium and Sphaerulina in the females were significantly higher than in the males(P<0.05).In contrast,the relative abundance of phyllosphere bacteria Spirosoma,Sphingomonas and fungi Elmerina,Suillus,Venturia and Zymoseptoria were significantly lower in the females than in the males(P<0.05).6.Redundancy analysis based on environmental factors and microbial community structure analysis showed that iron content was remarkably correlated with the differentiation of phyllosphere bacterial community composition,whereas mineral content significantly influenced phyllosphere fungal community structure of P.cathayana(P < 0.05).For the phyllosphere bacterial community,the leaf basic elements(carbon,nitrogen,phosphorus,etc.)were the main contributing factors,and the contribution rates were 66.14%,47.15% and 46.21% at the three altitudes,respectively.For the phyllosphere fungal community,the contribution rates of leaf basic elements were 29.25%,33.86% and 34.11% at the three altitudes,respectively.In addition,the contribution rates of leaf mineral elements to fungal community were 5.92%,14.03% and 7.59%,respectively.Taken together,the study showed that the female and male of P.cathayana had their own unique phyllosphere microbiota and the significantly enriched microbiota.The phyllosphere environment of female and male P.cathayana had a significant selective effect on microbial community structure.Moreover,the difference of phyllosphere microorganism between female and male was consistent in different altitudes.The results of this study provide a new method for the identification of dioecious plant gender by the difference of phyllosphere microbial composition and provide clues for the possible host-specific microbial species in the phyllosphere environment.It also provides a new research idea for further understanding the coevolutionary relationship between phyllosphere microorganisms and dioecious plants.