Elevated CO₂ stimulates plant growth and affects quantity and composition of root exudates, followed by response of its microbiome. Three scenarios representing nitrate fertilization regimes: limited (30 ppm), moderate (70 ppm) and excess nitrate (100 ppm) were compared under ambient and elevated CO₂ (eCO₂, 850 ppm) to elucidate their combined effects on root-surface-associated bacterial community abundance, structure and function. Wheat root-surface-associated microbiome structure and function, as well as soil and plant properties, were highly influenced by interactions between CO₂ and nitrate levels. Relative abundance of total bacteria per plant increased at eCO₂ under excess nitrate. Elevated CO₂ significantly influenced the abundance of genes encoding enzymes, transporters and secretion systems. Proteobacteria, the largest taxonomic group in wheat roots (~ 75%), is the most influenced group by eCO₂ under all nitrate levels. Rhizobiales, Burkholderiales and Pseudomonadales are responsible for most of these functional changes. A correlation was observed among the five gene-groups whose abundance was significantly changed (secretion systems, particularly type VI secretion system, biofilm formation, pyruvate, fructose and mannose metabolism). These changes in bacterial abundance and gene functions may be the result of alteration in root exudation at eCO₂, leading to changes in bacteria colonization patterns and influencing their fitness and proliferation.

升高的 CO ₂会刺激植物生长并影响根系分泌物的数量和组成，然后影响其微生物组的反应。_{代表硝酸盐施肥制度的三种情景：在环境和高浓度 CO 2} (eCO ₂ , 850 ppm)下比较有限 (30 ppm)、中等 (70 ppm) 和过量硝酸盐 (100 ppm ) 以阐明它们对根表面的综合影响-相关的细菌群落丰度、结构和功能。小麦根表面相关的微生物组结构和功能，以及土壤和植物特性，在很大程度上受到 CO ₂和硝酸盐水平之间相互作用的影响。每株植物总细菌的相对丰度在 eCO _2增加在过量的硝酸盐下。升高的 CO ₂显着影响了编码酶、转运蛋白和分泌系统的基因的丰度。变形菌是小麦根中最大的分类群（约占 75%），是所有硝酸盐水平下受 eCO _{2影响最大的群。}根瘤菌目、伯克氏菌目和假单胞菌目负责这些功能变化中的大部分。在丰度发生显着变化的五个基因组（分泌系统，特别是 VI 型分泌系统、生物膜形成、丙酮酸、果糖和甘露糖代谢）之间观察到相关性。细菌丰度和基因功能的这些变化可能是 eCO _{2根系分泌物改变的结果}, 导致细菌定植模式的变化并影响它们的适应性和增殖。