Comparison Of The Composition And Divergence Of The Rhizosphere Microbial In Wild Emmer,Domesticated Emmer And Durum Wheat Populations

Plant domestication is the primary driving force for agriculture formation,which also provides the foundation and prerequisite for the birth of human civilization as well as its continuous development.During the domestication process,significant changes have occurred in terms of agronomic traits,DNA,gene expression,metabolite synthesis in crops.With the advance of metagenomics,the importance of root microbiota playing in the healthy growth and development of plants was gradually revealed.However,comparative study of root microbiota composition and diversity between wild and cultivated crops is scarce,and the impacts and effects of domestication on the formation of root microbiota are still unclear in crops.Tetraploid wheat(Triticum turgidum L.),including wild emmer,domesticated emmer,and durum wheat,provides an ideal model system for crop domestication research.In order to preliminarily explore the influence of domestication on plant root microbiota,we used 16 S r DNA high-throughput sequencing technology to analyze the composition structure and differences of the root-associated bacterial communities among these 3 emmer wheat populations to obtain some insights about rhizosphere microbial dynamics driven by domestication in this study.The main research results are as follows:(1)Rhizosphere microbial composition and diversity analysis.In the rhizosphere bacterial community of tetraploid wheat,the abundance of Actinobacteria was the highest(35.7%),followed by Proteobacteria(26.7%),Acidobacteria(16.8%),Chloroflexi(6.4%)and Gemmatimonadetes(4.9%).By comparing the composition of bacterial communities in the rhizosphere of three tetraploid wheats,it was found that the species diversity gradually increased from wild emmer wheat to domesticated emmer wheat to durum wheat,and the diversity between groups was significantly different.Constrained principal coordinate analysis showed that the variance caused by tetraploid wheat sub-populations accounted for 5.76% of the total variance.A total of 130 core ASVs shared by three different tetraploid wheat cultivars.(2)Rhizosphere microbial difference analysis.The bacteria enriched in wild emmer wheat were Lechevalieria、Nitrospira、BIrii41、Acinetobacter、MND1、Ohtaekwangia、Haliangium and Cellvibrio,the bacteria enriched in domesticated emmer wheat were Skermanella 、 Nocardioides and Bacillus,the bacteria enriched in durum wheat were Solirubrobacter 、 67＿14 、 Gaiella and IMCC26256.Based on the random-forest machine-learning method,we also identified the 35 key rhizosphere bacterial communities that can differentiate different tetraploid wheat subgroups.By constructing co-occurrence networks,it was found that the rhizosphere microbial community of wild emmer wheat had more nodes and more complex networks than domesticated emmer wheat and durum wheat,while the nodes in the durum wheat rhizosphere microbial network were the most closely connected.(3)Correlation analysis between rhizosphere microbial and phenotypes and function prediction.Mantel test showed that the rhizosphere microbial of tetraploid wheat had significant correlation with plant height and thousand-grain weight.By calculating Pearson and Spearman correlation coefficients,it was found that rhizosphere microbial such as Lechevalieria,Nocardioides,Promicromonospora and Devosia were significantly positively correlated with plant height,and rhizosphere bacteria such as RB41,NMD1,Mycobacterium and IMCC26256 were significantly positively correlated with thousand grain weight.FAPROTAX software was used to annotate the metabolic functions of rhizosphere microbial in different tetraploid wheats,and a total of 55 functional groups were predicted.Among them,15 functions were significantly different in different tetraploid wheats,including aerobic ammonia oxidation,nitrogen fixation and nitrification,which were related to plant nutrient uptake.In this study,we investigated the structure,composition differences,correlation with phenotype and function prediction of rhizosphere microbial communities among wild emmer,domesticated emmer wheat and durum wheat,which lay the foundation for identifying beneficial bacteria closely related to agronomic traits,and also open the way to improve wheat traits from the perspective of rhizosphere microbial.