Host selection shapes crop microbiome assembly and network complexity.

Plant microbiomes are essential to host health and productivity but the ecological processes that govern crop microbiome assembly are not fully known. Here we examined bacterial communities across 684 samples from soils (rhizosphere and bulk soil) and multiple compartment niches (rhizoplane, root endosphere, phylloplane, and leaf endosphere) in maize (Zea mays)-wheat (Triticum aestivum)/barley (Hordeum vulgare) rotation system under different fertilization practices at two contrasting sites. Our results demonstrate that microbiome assembly along the soil-plant continuum is shaped predominantly by compartment niche and host species rather than by site or fertilization practice. From soils to epiphytes to endophytes, host selection pressure sequentially increased and bacterial diversity and network complexity consequently reduced, with the strongest host effect in leaf endosphere. Source tracking indicates that crop microbiome is mainly derived from soils and gradually enriched and filtered at different plant compartment niches. Moreover, crop microbiomes were dominated by a few dominant taxa (c. 0.5% of bacterial phylotypes), with bacilli identified as the important biomarker taxa for wheat and barley and Methylobacteriaceae for maize. Our work provides comprehensive empirical evidence on host selection, potential sources and enrichment processes for crop microbiome assembly, and has important implications for future crop management and manipulation of crop microbiome for sustainable agriculture.

Effects of long-term Wuqinxi exercise on working memory in older adults with mild cognitive impairment.

PURPOSE: Although physical exercise may improve memory in older adults, whether the Chinese traditional fitness exercise Wuqinxi improves working memory and delays cognitive deterioration in older adults with mild cognitive impairment (MCI) has not been assessed in randomized controlled experiments. METHODS: Fifty older adults with MCI based on their Montreal Cognitive Assessment scores were randomized to either a Wuqinxi exercise group or a non-exercise control group. The exercise group engaged in Wuqinxi once a week for 60 min each session for 40 weeks. Participants in the control group received no intervention and maintained their regular living habits. The n-back paradigm was used to measure changes in working memory before and after Wuqinxi exercise. RESULTS: In the 0-back task, the response speed of older adults with MCI who participated in Wuqinxi was faster than that of older adults with MCI in the non-exercise control group (P = 0.031); there was no significant difference in accuracy between the two groups (P > 0.05). In the 1-back and 2-back tasks, there was no significant difference in response times or in accuracy between the two groups (P > 0.05). CONCLUSIONS: In this randomized controlled study, participation in long-term Wuqinxi delayed the deterioration of working memory in older adults with MCI, suggesting that this exercise may be an effective intervention to delay or prevent the progression of MCI to Alzheimer's disease.