Sheng Zhou

Urban greening programs in Chinese megacities are premised on the assumption that vegetation cools the surface and improves air quality simultaneously, yet greenness is usually quantified in two dimensions and the thermal and air-quality services are evaluated separately, so the places where they reinforce or conflict remain unmapped. We measured effective leaf area index (LAIe) in 570 quadrats across 30 vegetated plots in Guangzhou, China, and found that, under the spatial and temporal conditions tested, planar spectral data represented it poorly: Moderate Resolution Imaging Spectroradiometer (MODIS) LAI was only weakly correlated with field values (r = 0.15, n = 395), 87.9% of LAIe variance occurred within plots, and all 16 locally calibrated vegetation-index models showed no skill under plot-grouped cross-validation (CV-R² ≤ 0). We therefore represented three-dimensional greenness with a structural proxy, layered vegetation volume (LVV, m³ m⁻²), defined as the product of cell-mean 10 m canopy height and tree-cover fraction (a cover-weighted canopy-height index), and coupled it with warm-season Landsat land surface temperature (LST) and 1 km estimates of PM_2.5 (2016–2022), warm-season daily maximum 8 h average (MDA8) O₃ (2016–2022) and NO₂ (2019–2022) on 1, 2, 3 and 5 km grids, analyzed with ordinary least squares (OLS), geographically weighted regression (GWR), multiscale geographically weighted regression (MGWR) and extreme gradient boosting with Shapley additive explanations (XGBoost–SHAP). The results show the following: (1) MGWR achieved lower corrected Akaike information criterion (AICc) than OLS and GWR at every scale where it was fitted (2, 3 and 5 km), and the LVV term operated at a bandwidth of 43 neighbors (median radius ≈ 12 km) versus ≥863 neighbors (≈108 km, effectively citywide) for meteorological covariates; (2) one standard deviation of LVV (7.4 m³ m⁻²) was associated with 1.3 °C lower warm-season LST (significantly negative in 75% of cells at |t| > 1.96 and 37% under MGWR-adjusted critical values), 0.30 μg m⁻³ lower PM_2.5 (69% and 50%) and 1.3 μg m⁻³ lower NO₂; (3) the citywide O₃ effect was null, but MGWR revealed offsetting local responses (31% of cells significantly negative, 17% positive), and within-cell greening was associated with rising O₃ (+0.19 SD, p < 0.001), and annual coefficients turned non-negative after 2020 as nitrogen oxides (NO_x) declined; (4) the PM_2.5 benefit leveled off near 13.6 m³ m⁻² (bootstrap 95% CI 8.4–15.2), while the cooling response flattened gradually with a poorly constrained breakpoint, and cells classified as full synergy, partial synergy, O₃ trade-off and insensitive covered 44.6%, 36.3%, 15.0% and 4.1% of the municipality, with trade-off cells concentrated in the hottest, most built-up southern lowland belt; under stricter significance criteria the classified shares contracted, while the trade-off cells remained in this belt. These results suggest that structure-based, zone-specific greening targets may help secure co-benefits while anticipating a possible ozone penalty in NO_x-rich areas.

Postharvest lignification of juice sacs in Meizhou pomelo is a major physiological disorder that compromises fruit quality and limits sustainable industry development. Through a comprehensive three-year field study, we investigated the effects of key factors—soil organic matter, storage temperature, and tree age—on fruit lignification, and evaluated the efficacy of ten plant growth regulators (PGRs) and their combinations in mitigating granulation. Our results demonstrated that soil rich in organic matter and exchangeable calcium significantly reduced the granulation index. Constant storage at 15 °C effectively suppressed weight loss and lignification compared to fluctuating ambient temperatures. Among the tested PGRs, 28-Homobrassinolide (28-homo-BR), 28-Epihomobrassinolide (28-epi-BR), 24-Epibrassinolide (24-epi-BR), and 14-Hydroxybrassinosteroid (14-hydro-BR) exhibited the most pronounced effects in alleviating granulation. Two superior PGR combinations were subsequently identified, which functioned by synergistically downregulating the activities of key phenylpropanoid pathway enzymes—phenylalanine ammonia-lyase, 4-coumarate: CoA ligase, cinnamyl alcohol dehydrogenase, and peroxidase. This downregulation likely contributed to reduced lignin biosynthesis and accumulation. Metabolomic profiling further revealed an accumulation of phenylpropanoid precursors, including ferulic acid and p-coumaric acid, in lignified juice sacs, indicating that the overactivation of this pathway is a key metabolic feature associated with lignification. This finding provides critical evidence for the potential mechanism whereby PGRs suppress lignification, thus offering both mechanistic insights and practical strategies for controlling lignification in pomelo and other citrus fruits.

Closely-related plant groups with distinct microbiomes, chemistries and ecological characteristics represent tractable models to explore mechanisms shaping species spread, competitive dynamics and community assembly at the interface of native and introduced ranges. We investigated phyllosphere microbial communities, volatile organic compound (VOC) compositions, and potential interactions among introduced S. trilobata, native S. calendulacea and their hybrid in South China. S. trilobata exhibited higher α diversity but significantly different community composition compared to the native and hybrid groups. However, S. calendulacea and the hybrid shared certain microbial taxa, suggesting potential gene flow or co-existence. The potent antimicrobial VOC profile of S. trilobata, including unique compounds like p-cymene (13.33%), likely contributes to its invasion success. The hybrid’s intermediate microbial and VOC profiles suggest possible consequences for species distribution, genetic exchange, and community assembly in heterogeneous environments. This hybrid deserves further study as both an opportunity for and threat to diversity maintenance. These differentiating yet connected plant groups provide insight into ecological and evolutionary dynamics shaping microbiome structure, species co-occurrence and competitive outcomes during biological exchange and habitat transformation. An interdisciplinary approach combining chemical and microbial ecology may reveal mechanisms underlying community stability and change, informing management of species spread in a globalized world.

The seeds of Camellia oleifera produce high amount of oil, which can be broadly used in the fields of food, industry, and medicine. However, the molecular regulation mechanisms of seed development and oil accumulation in C. oleifera are unclear. In this study, evolutionary and expression analyses of the MADS‐box gene family were performed across the C. oleifera genome for the first time. A total of 86 MADS‐box genes (ColMADS) were identified, including 60 M‐type and 26 MIKC members. More gene duplication events occurred in M‐type subfamily (6) than that in MIKC subfamily (2), and SEP-like genes were lost from the MIKC^C clade. Furthermore, 8, 15, and 17 differentially expressed ColMADS genes (DEGs) were detected between three developmental stages of seed (S1/S2, S2/S3, and S1/S3), respectively. Among these DEGs, the STK-like ColMADS12 and TT16-like ColMADS17 were highly expressed during the seed formation (S1 and S2), agreeing with their predicted functions to positively regulate the seed organogenesis and oil accumulation. While ColMADS57 and ColMADS07 showed increasing expression level with the seed maturation (S2 and S3), conforming to their potential roles in promoting the seed ripening. In all, these results revealed a critical role of MADS‐box genes in the C. oleifera seed development and oil accumulation, which will contribute to the future molecular breeding of C. oleifera.