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.植物叶片定殖有一类特定的附生微生物（microbial epiphytes）。本研究通过检测玉米重组自交系（recombinant inbred, RI）作图群体中的附生细菌核糖体DNA（ribosomal DNA）多样性，探究了植物遗传因子与太阳UV-B辐射对叶围（phyllosphere）微生物多样性的影响。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影响。具有等位基因特异性效应的候选基因被定位至与细菌多样性相关的染色体区域：一个谷氨酸脱羧酶（glutamate decarboxylase）候选基因位于UV-B特异性染色体位点上；在细菌多样性表型截然相反的两个RI系的对比中，高细菌多样性与高水平的谷氨酸脱羧酶活性相关，而该酶是γ-氨基丁酸（gamma-aminobutyric acid, GABA）通路的组成成分。细菌多样性位点与田间南方叶枯病（Southern leaf blight, SLB）感病性相关位点存在显著重叠。对SLB具有抗性的自交基因型的β细菌多样性更低，而对自交系施以抗生素处理后，该多样性水平显著升高。上述结果表明，GABA通路在遗传层面与叶围细菌多样性存在关联。此外，与低细菌多样性相关的QTL与真菌枯病抗性QTL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的群落变异性，并提升植物对真菌侵染的抗性。