Microbes influence plant phenotypes but most known examples of this are from the study of below-ground microbes and plant disease modification. To examine the potential importance of phyllosphere microbes on non-disease related plant traits, we used sterile Arabidopsis clones to test the effects of foliar fungi on flowering phenology and reproductive allocation under conditions of varying water stress. We inoculated the sterile plants with fully-factorial combinations of four fungal isolates, then measured flowering time and reproductive allocation for each treatment group under normal and water-stressed conditions. All plants inoculated with foliar fungi had significantly later flowering and greater seed mass than the sterile control groups. The magnitude of this effect depended on the specific fungi present, but individual fungal effects diminished as inoculum richness increased. Above-ground microbes likely influence other plant traits as well and should be considered in any study measuring plant phenotypes.

微生物影响植物的表型，但是最著名的例子来自地下微生物的研究和植物病害的改良。为了研究叶际微生物对非疾病相关植物性状的潜在重要性，我们使用了无菌拟南芥克隆以测试在水分胁迫条件下叶真菌对开花物候和生殖分配的影响。我们用四种真菌分离物的全因子组合接种无菌植物，然后在正常和水分胁迫条件下测量每个处理组的开花时间和生殖分配。与无菌对照组相比，所有接种了叶真菌的植物的开花时间都明显较晚，种子质量也更大。这种作用的程度取决于存在的特定真菌，但是随着接种量的增加，单个真菌的作用减弱。地上微生物也可能影响其他植物性状，在任何测量植物表型的研究中都应考虑。