Plants have diverse microbiomes, which have profound effects on their hosts. But it is not yet known if, or how, plant hosts influence their microbiomes. Recently, researchers comprehensively examined the influence maize has on its microbiomes. Plant developmental stage had a stronger influence on plant microbiomes than on soil microbiomes and the strongest effect was on the phylloplane. Phylloplane microbiomes were co-shaped by both plant growth and seasonal environmental factors, with the air as its important source. Phylloplane bacteria and fungi took on different roles in the early and late stages. In plant compartments, deterministic processes had the strongest effect on bacterial communities at the early stage and then on fungal communities at the late stage. The microbial interkingdom network and crop yield predication also followed this pattern - bacterial taxa played the most important role in the early stage and fungal taxa in the late stage, respectively. Metagenomic analyses showed that, compared to other stages, early-stage phylloplane microbiomes had higher functional diversity. Functional genes related to nutrient provision were enriched at the early stage, and those related to N assimilation and C degradation were enriched at the late stage. These results suggest that host developmental stage profoundly influences plant microbiome assembly and functions and shows that bacterial and fungal microbiomes take on different ecological roles in each stage.