Leaf side determines the relative importance of dispersal versus host filtering in the phyllosphere microbiome.

Leaves harbor distinct microbial communities that can have an important impact on plant health and microbial ecosystems worldwide. Nevertheless, the ecological processes that shape the composition of leaf microbial communities remain unclear, with previous studies reporting contradictory results regarding the importance of bacterial dispersal versus host selection. This discrepancy could be driven in part because leaf microbiome studies typically consider the upper and lower leaf surfaces as a single entity despite these habitats possessing considerable anatomical differences. We characterized the composition of bacterial phyllosphere communities from the upper and lower leaf surfaces across 24 plant species. Leaf surface pH and stomatal density were found to shape phyllosphere community composition, and the underside of leaves had lower richness and higher abundances of core community members than upper leaf surfaces. We found fewer endemic bacteria on the upper leaf surfaces, suggesting that dispersal is more important in shaping these communities, with host selection being a more important force in microbiome assembly on lower leaf surfaces. Our study illustrates how changing the scale in which we observe microbial communities can impact our ability to resolve and predict microbial community assembly patterns on leaf surfaces. IMPORTANCE Leaves can harbor hundreds of different bacterial species that form unique communities for every plant species. Bacterial communities on leaves are really important because they can, for example, protect their host against plant diseases. Usually, bacteria from the whole leaf are considered when trying to understand these communities; however, this study shows that the upper and lower sides of a leaf have a very different impact on how these communities are shaped. It seems that the bacteria on the lower leaf side are more closely associated with the plant host, and communities on the upper leaf side are more impacted by immigrating bacteria. This can be really important when we want to treat, for example, crops in the field with beneficial bacteria or when trying to understand host-microbe interactions on the leaves.

The investigation of etiology of the fetal death and interventions / 中国基层医药

Objective To analyze the factors related to the fetal death and to find the effective interventions. Methods 84 women with fetal death were recruited.Clinical data were collected and analyzed based on the retro-spective method.Results Among the 84 women,21 women with pregnancy complications,2 women delivered fetal macrosomia,2 women with oligohydramnios,4 women with polyhydramnios,50 women with abnormal umbilical cord, 1 woman with fetal growth restriction,1 woman with racket -shaped placenta,2 women with unknown causes,and 1 woman with placental calcification.Conclusion The main cause of fetal death was pregnancy complications and umbilical cord abnormalities.The early diagnosis,promptly correct,and timely termination of pregnancy will be the effective interventions to prevent the development of the fetal death.