Planting for posterity
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Tomato growth stage modulates bacterial communities across different soil aggregate sizes and disease levels
Soil aggregates contain distinct physio-chemical properties across different size classes. These differences in micro-habitats support varied microbial communities and modulate the effect of plant on microbiome, which affect soil functions such as disease suppression. However, little is known about how the residents of different soil aggregate size classes are impacted by plants throughout their growth stages. Here, we examined how tomato plants impact soil aggregation and bacterial communities within different soil aggregate size classes. Moreover, we investigated whether aggregate size impacts the distribution of soil pathogen and their potential inhibitors. We collected samples from different tomato growth stages: before-planting, seedling, flowering, and fruiting stage. We measured bacterial density, community composition, and pathogen abundance using qPCR and 16 S rRNA gene sequencing. We found the development of tomato growth stages negatively impacted root-adhering soil aggregation, with a gradual decrease of large macro-aggregates (1–2 mm) and an increase of micro-aggregates (<0.25 mm). Additionally, changes in bacterial density and community composition varied across soil aggregate size classes. Furthermore, the pathogen exhibited a preference to micro-aggregates, while macro-aggregates hold a higher abundance of potential pathogen-inhibiting taxa and predicted antibiotic-associated genes. Our results indicate that the impacts of tomatoes on soil differ for different soil aggregate size classes throughout different plant growth stages, and plant pathogens and their potential inhibitors have different habitats within soil aggregate size classes. These findings highlight the importance of fine-scale heterogeneity of soil aggregate size classes in research on microbial ecology and agricultural sustainability, further research focuses on soil aggregates level could help identify candidate tax involved in suppressing pathogens in the virtual micro-habitats.
Crop rotation increases Tibetan barley yield and soil quality on the Tibetan Plateau
Tibetan barley (Hordeum vulgare) accounts for over 70% of the total food production in the Tibetan Plateau. However, continuous cropping of Tibetan barley causes soil degradation, reduces soil quality and causes yield decline. Here we explore the benefits of crop rotation with wheat and rape to improve crop yield and soil quality. We conducted 39 field experiments on the Tibetan Plateau, comparing short-term (≤5 years), 5–10 years and long-term (≥10 years) continuous cropping with rotation of Tibetan barley with wheat or rape. Results showed that Tibetan barley–wheat and Tibetan barley–rape rotations increased yields by 17% and 12%, respectively, while improving the soil quality index by 11% and 21%, compared with long-term continuous cropping. Both Tibetan barley rotations with wheat and rape improved soil quality and consequently yield, mainly by increasing soil microbial biomass nitrogen and microbial biomass carbon and decreasing pH. By contrast, long-term continuous cropping led to decreased soil organic matter, lower microbial biomass nitrogen and increased pH, contributing to yield decline. The benefits of rotations on crop yield and soil quality increased over time. Implementing crop rotation with wheat or rape thus offers a sustainable agricultural strategy for improving food security on the Tibetan Plateau.
Characterization of cis-polyisoprene produced in Periploca sepium, a novel promising alternative source of natural rubber
Natural rubber is an important industrial raw material and is almost exclusively produced from Hevea brasiliensis latex. Because H. brasiliensis is limited its cultivation to specific tropical regions, the insufficient capacity of natural rubber has become increasingly urgent. To develop a novel alternative plant for natural rubber production, we selected a perennial shrub Periploca sepium, which is widely distributed from tropical to temperate regions. P. sepium can produce latex and contains the rubber component polyisoprene with a high-molecular-weight distribution ranging from 104-106. Its main chain structure was identified as cis-1,4-polyisoprene, similar to that of H. brasiliensis. The polyisoprenes were observed to be present mainly in the secondary phloem adjacent to the cambium and pith, and almost entirely overlapped with the distributions of three rubber particle-associated proteins, cis-prenyltransferase (CPT), small rubber particle protein (SRPP) and rubber elongation factor (REF). The three genes were genome edited via CRISPR-Cas9 in P. sepium, and the total contents and high-molecular-mass regions of the cis-polyisoprenes in the transgenic plants with mutations were reduced to different degrees, indicating that the three genes apparently play important roles in natural rubber biosynthesis. This research will promote the development of P. sepium as an alternative source of natural rubber.
Neural codes track prior events in a narrative and predict subsequent memory for details
Throughout our lives, we learn schemas that specify what types of events to expect in particular contexts and the temporal order in which these events usually occur. Here, our first goal was to investigate how such context-dependent temporal structures are represented in the brain during processing of temporally extended events. To accomplish this, we ran a 2-day fMRI study (N = 40) in which we exposed participants to many unique animated videos of weddings composed of sequences of rituals; each sequence originated from one of two fictional cultures (North and South), where rituals were shared across cultures, but the transition structure between these rituals differed across cultures. The results, obtained using representational similarity analysis, revealed that context-dependent temporal structure is represented in multiple ways in parallel, including distinct neural representations for the culture, for particular sequences, and for past and current events within the sequence. Our second goal was to test the hypothesis that neural schema representations scaffold memory for specific details. In keeping with this hypothesis, we found that the strength of the neural representation of the North/South schema for a particular wedding predicted subsequent episodic memory for the details of that wedding.
Scale-dependent cloud enhancement from land restoration in West African drylands
Land restoration projects, including reforestation and area protection, are being implemented across African drylands such as the Sahel. In addition to biodiversity, livelihood and carbon sequestration benefits, restoration can also affect the local climate through land-atmosphere interaction. Yet, it remains unknown to what extent dryland restoration can affect cloud cover development and, ultimately, precipitation. Here, we use twenty years of high-resolution data from the Meteosat Second Generation satellite to study the impact of land restoration on cloud development in West African drylands. Results show that cloud cover frequency and convective initiation are higher above vegetated areas, particularly during the start and end of the wet seasons. Furthermore, we find a more pronounced cloud cover enhancement over protected areas larger than 121 km2, suggesting a scale-dependent relationship between project size and cloud cover development.
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