Lina Zhang

The cone is a crucial component of the whole life cycle of gymnosperm and an organ for sexual reproduction of gymnosperms. In Pinus koraiensis, the quantity and development process of male and female cones directly influence seed production, which in turn influences the tree’s economic value. There are, however, due to the lack of genetic information and genomic data, the morphological development and molecular mechanism of female and male cones of P. koraiensis have not been analyzed. Long-term phenological observations were used in this study to document the main process of the growth of both male and female cones. Transcriptome sequencing and endogenous hormone levels at three critical developmental stages were then analyzed to identify the regulatory networks that control these stages of cones development. The most significant plant hormones influencing male and female cones growth were discovered to be gibberellin and brassinosteroids, according to measurements of endogenous hormone content. Additionally, transcriptome sequencing allowed the identification of 71,097 and 31,195 DEGs in male and female cones. The synthesis and control of plant hormones during cones growth were discovered via enrichment analysis of key enrichment pathways. FT and other flowering-related genes were discovered in the coexpression network of flower growth development, which contributed to the growth development of male and female cones of P. koraiensis. The findings of this work offer a cutting-edge foundation for understanding reproductive biology and the molecular mechanisms that control the growth development of male and female cones in P. koraiensis.

In the summer of 2019, field measurements of ozone (O₃) and its precursors[volatile organic compounds (VOCs) and nitrogen oxides (NO_x)] were carried out at an urban site in Ji'nan. We found that the daily maximum 8-hour averages φ(O₃) were (103.0±14.5)×10^-9. The average φ(NO_x) and φ(VOCs), which are ozone precursors, were (16.7±11.3)×10^-9and (22.4±9.4)×10^-9, respectively. The ·OH reactivity of VOCs was determined (9.6±3.8) s^-1. Ji'nan suffered from serious O₃ pollution. An observation-constrained chemical box model was deployed to evaluate in situ photochemical O₃ production, which indicated that chemical reactions made positive contributions to O₃ production rates between 07:00 and 19:00 LT, with the average hourly O₃ production rate of 35.6×10^-9 h^-1. To evaluate the effectiveness of various ozone precursor control strategies in reducing ozone pollution, we combined the observation-based model (OBM) with the relative incremental reactivity (RIR) method. The key indicators that affect the local ozone production rate were identified. Ji'nan was under VOC-limited conditions and the key VOC precursors were alkenes. The O₃ formation mechanism changed from the VOC-limited regime in the morning to the transitional regime in the afternoon. Correspondingly, the simulated local O₃ production rate was increased from 18.3×10^-9 h^-1 to 29.6×10^-9 h^-1. To further explore the role of anthropogenic emissions in ozone pollution, we used the positive matrix factorization (PMF) model to identify the major sources contributing to VOCs. The major sources in Ji'nan were vehicular exhaust and gasoline evaporation, accounting for more than 50% of the observed VOCs. Therefore, constraints on vehicular emissions is the most effective strategy to control O₃ pollution in Ji'nan.