Tingting Cao

Rapid growth of Moso bamboo (Phyllostachys edulis) shoots (offspring ramet) is primarily fuelled by nitrogen (N) derived from parent ramet and absorbed by rhizome roots. However, the extent to which each N source supports the growth of offspring ramet and the underlying molecular mechanisms of N transport remain unclear. Here, clonal fragments consisting of a parent ramet, an offspring ramet, and an interconnected rhizome were established in a Moso bamboo forest. Additionally, 15N isotope tracing and transcriptome profiling were conducted concurrently to quantify the N contribution from the parent ramet and rhizome roots to the offspring ramet, and to reveal the molecular mechanisms underlying N transport during rapid growth (i.e. early, peak, branching, and leafing stages). The N acquisition strategy of offspring ramet shifted from being primarily provided by the parent ramet (72.53%) during early stage to being predominantly absorbed by rhizome roots (69.85%) during the leafing stage. Approximately equal N contributions (45.82%–54.18%) from the parent ramet and rhizome roots were observed during peak and branching stages. PeAAP29123 was identified as a key gene for N transport, being most closely correlated with 15N content. Biomolecular assays demonstrated that PeHDZ23987 could activate the expression of PeAAP29123 via two types of HD-motifs. Overexpression of PeHDZ23987 and PeAAP29123 significantly enhanced N starvation tolerance in transgenic rice with significantly improved N uptake efficiency. Our findings clarify the pattern and mechanisms of N supply for the rapid growth of Moso bamboo offspring ramet and provide transcriptomic evidence for long-distance N transport between clonal ramets.

Microplastic pollution is a research hotspot around the world. This study investigated the characteristics of microplastic pollution in the freshwater environments of 21 major cities across China. Through indoor and outdoor experimental analysis, we have identified the spatial and temporal distribution characteristics of microplastic pollution in China’s freshwater environments. Our findings indicate that the average concentration of microplastics in China’s freshwater environments is 3502.6 n/m³. The majority of these microplastics are fibrous (42.5%), predominantly smaller than 3 mm (28.1%), and mostly colored (64.7%). The primary chemical components of these microplastics are polyethylene (PE, 33.6%), polyvinyl chloride (PVC, 21.5%), polypropylene (PP, 16.8%), and polystyrene (PS, 15.6%). The abundance of microplastics in China’s freshwater environments generally tends to increase from west to east and from south to north, with the lowest concentration found in Xining, Qinghai (1737.5 n/m³), and the highest in Jiamusi, Heilongjiang (5650.0 n/m³). The distribution characteristics of microplastics are directly related to land use types, primarily concentrated in areas of intense human activity, including agricultural, transport, and urban land. Seasonal changes affect the abundance of microplastics, peaking in summer, followed by spring and autumn, mainly due to variations in rainfall, showing a positive correlation.