Data from: Maize leaf epiphytic bacteria diversity patterns are genetically correlated with resistance to fungal pathogen infection

Plant leaves host a specific set of microbial epiphytes. Plant genetic and solar UV-B radiation effects on the diversity of the phyllosphere were examined by measuring epiphytic bacterial ribosomal DNA diversity in a maize recombinant inbred (RI) mapping population. Several chromosomal quantitative trait loci (QTL) with significant effects on bacterial diversity were identified, some of which had effects only in the presence of UV-B radiation and others that had effects both with and without UV-B. Candidate genes with allele-specific effects were mapped to the bacterial diversity chromosomal regions. A glutamate decarboxylase candidate gene was located at a UV-B–specific chromosomal locus, and in a comparison between two RI lines with contrasting bacterial diversity phenotypes, high bacterial diversity was associated with high levels of glutamate decarboxylase enzyme activity, a component of the gamma-aminobutyric acid (GABA) pathway. The bacterial diversity loci exhibited a significant overlap with loci connected with Southern leaf blight (SLB) susceptibility in the field. A SLB-resistant inbred genotype had less beta bacterial diversity, and antibiotic treatment of inbreds increased this diversity. These results suggest that the GABA pathway is genetically associated with phyllosphere bacterial diversity. Furthermore, the colocalization of QTL between low bacterial diversity and fungal blight–resistance and the increase in beta diversity in antibiotic-treated leaves suggest that occupation of leaf habitats by a particular set of suppressive bacteria may restrict phyllosphere bacterial variability and increase resistance to fungal infection.

植物叶片定殖有一组特异的附生微生物（microbial epiphytes）。本研究通过在玉米重组自交系（recombinant inbred, RI）作图群体中测定附生细菌的核糖体DNA多样性，探究了植物遗传因子与太阳UV-B辐射对植物叶围（phyllosphere）细菌多样性的调控效应。研究鉴定出多个对细菌多样性具有显著调控作用的染色体数量性状位点（quantitative trait loci, QTL），其中部分位点仅在UV-B辐射存在时发挥效应，其余位点则在UV-B辐射存在与否的条件下均能产生调控作用。研究将携带等位基因特异性效应的候选基因定位至细菌多样性相关的染色体区域。在一个UV-B辐射特异性的染色体位点上，发现了谷氨酸脱羧酶（glutamate decarboxylase）候选基因；在两个细菌多样性表型差异显著的RI系间的对比实验中，高细菌多样性与γ-氨基丁酸（GABA）通路的组分——谷氨酸脱羧酶的高活性显著相关。细菌多样性相关位点与田间条件下关联南方叶枯病（Southern leaf blight, SLB）感病性的位点存在显著重叠。对南方叶枯病抗性自交系的分析显示，其β细菌多样性水平更低；而对自交系叶片进行抗生素处理后，该β多样性水平显著升高。上述结果表明，GABA通路与植物叶围细菌多样性存在遗传关联。此外，低细菌多样性数量性状位点与真菌枯病抗性位点的共定位现象，以及抗生素处理叶片中β多样性的升高，提示特定类群的抑菌细菌占据叶片生境后，可能会限制叶围细菌群落的变异性，并提升植物对真菌侵染的抗性。