The current research was aimed to study the effects of different land use types (LUT) and soil depth (SD) on soil enzyme activity, metal content, and soil fungi in the karst area. Soil samples with depths of 0–20 cm and 20–40 cm were collected from different land types, including grassland, forest, Zanthoxylum planispinum land, Hylocereus spp. land and Zea mays land. The metal content and enzyme activity of the samples were determined, and the soil fungi were sequenced. The results showed that LUT had a significant effect on the contents of soil K, Mg, Fe, Cu and Cr; LUT and SD significantly affected the activities of invertase, urease, alkaline phosphatase and catalase. In addition, Shannon and Chao1 index of soil fungal community was affected by different land use types and soil depths. Ascomycota, Basidiomycota and Mortierellomycota were the dominant phyla at 0–20 cm and 20–40 cm soil depths in five different land types. Land use led to significant changes in soil fungal structure, while soil depth had no significant effect on soil fungal structure, probably because the small-scale environmental changes in karst areas were not the dominant factor in changing the structure of fungal communities. Additionally, metal element content and enzyme activity were related to different soil fungal communities. In conclusion, soil mineral elements content, enzyme activity, and soil fungal community in the karst area were strongly affected by land use types and soil depths. This study provides a theoretical basis for rational land use and ecological restoration in karst areas.

To reveal the effect of the interactions between soil depth and different land use types on soil nutrients and soil bacterial communities in a karst area, fifty soil samples from five different karst land use types in Huajiang town, Guizhou province, Southwest China were collected, and the soil bacteria were analyzed using high-throughput absolute quantification sequencing. Our results showed that land use types (LUT) and soil depth (SD) significantly influenced the content of soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), nitrate nitrogen (NN), ammonium nitrogen (AN) and available soil phosphorus (AP), and pH; further, the interaction of LUT and SD also significantly influenced SOC, NN, NA, AP, and pH. In addition, LUT clearly impacted the Chao1 and Shannon indexes, but, SD and LUT * SD markedly affect Chao1 and Shannon index, respectively. All the soil bacterial communities were significantly different in the five different five land use types according to PERMANOVA. Importantly, Acidobacteria and Proteobacteria were the predominant phyla at soil depths of 0–20 cm and 20–40 cm among all the LUTs. At 0–20 cm, TN, AN, and SOC exerted a strong positive influence on Acidobacteria, but NN exerted a strong negative influence on Acidobacteria; at 20–40 cm soil, TN and AN exerted a strong positive influence on Acidobacteria; TP exerted no marked influence on any of the phyla at these two soil depths. At 0–20 cm of soil depth, we also found that Chao1 index changes were closely related to the TN, SOC, AN, and NN; similarly, Shannon index changes were significantly correlated to the AN, TN, and SOC; the PCoA was clearly related to the TN, SOC, and AN. Interestingly, at soil depth of 20–40 cm, Chao 1 was markedly related to the TN and pH; Shannon was markedly correlated with the SOC, TP, AN, and AP; and the PCoA was significantly correlated with the TN and pH. Our findings imply that soil nutrients and soil bacteria communities are strongly influenced by land use types and soil depth in karst areas.

The petal blight disease of alpine Rhododendron severely impacts the ornamental and economic values of Rhododendron. Plant secondary metabolites play a crucial role in resisting pathogenic fungi, yet research on metabolites in alpine Rhododendron petals that confer resistance to pathogenic fungi is limited. In the present study, the secondary metabolites in Rhododendron delavayi, R. agastum, and R. irroratum petals with anti-pathogenic activity were screened through disease index analysis, metabolomic detection, the mycelial growth rate, and metabolite spraying experiments. Disease index analysis revealed that R. delavayi petals exhibited the strongest disease resistance, while R. agastum showed the weakest, both under natural and experimental conditions. UHPLC-QTOF-MS/MS analysis identified 355 and 274 putative metabolites in positive and negative ion modes, respectively. The further antifungal analysis of differentially accumulated baicalein, diosmetin, and naringenin showed their half-inhibitory concentrations (IC50) against Neopestalotiopsis clavispora to be 5000 mg/L, 5000 mg/L, and 1000 mg/L, respectively. Spraying exogenous baicalein, diosmetin, and naringenin significantly alleviated petal blight disease caused by N. clavispora infection in alpine Rhododendron petals, with the inhibition rates exceeding 64%. This study suggests that the screened baicalein, diosmetin, and naringenin, particularly naringenin, can be recommended as inhibitory agents for preventing and controlling petal blight disease in alpine Rhododendron.

Over the past two decades, the tea plantation area in Meitan County, China, has expanded nearly 30-fold, driving significant land use and cover changes (LUCC) with unclear impacts on regional carbon storage. This study uses the PLUS-InVEST model to analyze LUCC impacts on carbon storage from 2000 to 2020 and predict future changes by 2060. Results show a decline in total carbon storage from 3977.83 × 10⁴ t in 2000 to 3960.85 × 10⁴ t in 2020, primarily due to reductions in cultivated land and grassland. Although carbon storage in forest land and tea plantations increased, the overall trend remained negative. Multi-scenario simulations indicate that the sustainable development scenario (SDS) mitigates carbon loss, with a decrease of 31.53 × 10⁴ t, compared to larger reductions in the natural development (NDS) and economic development (EDS) scenarios. Under the SDS scenario, carbon storage in forest land and grassland increased while construction land expansion was controlled. This study emphasizes optimizing land use and agricultural management to enhance carbon sequestration and protect ecosystems, highlighting the need for a balance between ecological protection and economic development for sustainable carbon management in Meitan County.

Background/Objectives: Calcium-dependent protein kinases (CDPKs) are a crucial class of calcium-signal-sensing and -response proteins that significantly regulate abiotic stress. Yinshania henryi is a member of the Brassicaceae family that primarily grows in the karst regions of southwestern China, with a notable tolerance to high-calcium soils. Currently, the function of the CDPK family of genes in Y. henryi has yet to be explored. Methods: This study employed a comprehensive approach starting with bioinformatic methods to analyze the whole-genome sequencing data of Y. henryi and identified YhCDPK genes by combining phylogenetic characteristics and protein domain analysis. Results: It then delved into the physicochemical properties, gene structure, chromosomal localization, phylogenetic tree, and promoter cis-acting elements of these YhCDPK genes. Subsequently, RNA-seq data and qRT-PCR analysis were utilized to understand the expression patterns of YhCDPK genes. Twenty-eight YhCDPK genes were found to be unevenly distributed across six chromosomes; these can be classified into four subfamilies, with many cis-acting elements in their promoter regions involved in plant growth and stress responses. Furthermore, the differential expression patterns of YhCDPK genes under different concentrations of calcium treatments were investigated using RNA-seq data and qRT-PCR analysis. Conclusions: These results are a critical first step in understanding the functions of YhCDPK genes, and they lay a foundation for further elucidating the adaptability and response mechanism of YhCDPK genes in Y. henryi to the karst environment.