The APETALA3/DEFICIENS (AP3/DEF) gene is a B-class gene of the MADS-box gene family, which is mainly involved in the regulation of petal and stamen development during flower development. Cloning and analysis of the AP3/DEF homologous genes from Rhus chinensis can help exploring their role in the development of stamen. The CDS of AP3/DEF homologous gene was obtained using RT-PCR; its sequence and structural domains were compared and analyzed by NCBI CD Search; interactions between AP3/DEF homologous proteins and other MADS-box transcription factors in R. chinensis were verified by using yeast two-hybrid system; real-time fluorescence PCR was used to analyze the spatial and temporal expression patterns of the AP3/DEF homologous genes; overexpression in Arabidopsis was conducted to verify the function of the AP3/DEF homologous genes in flower organ development. Two coding sequences of AP3/ DEF homologous genes in R. chinensis were cloned and named RcAP3 (GenBank: OR962160) and RcTM6 (GenBank: OR962159). Based on the alignment of their conserved amino acid domains and phylogenetic analysis, these two protein sequences showed the closest genetic relationship to the AP3/DEF homologous gene-encoded proteins in the Anacardiaceae family, including Mangifera indica and Pistacia vera. The yeast two-hybrid results showed that RcAP3 and RcTM6 interacted with the B-class protein RcPI, the C-class proteins RcAG and Rcag in R. chinensis, but not with the A-class and E-class proteins. Real-time fluorescence quantification results demonstrated that RcAP3 and RcTM6 were highly expressed during the rapid growth stage of flower buds in different sexes of R. chinensis, with lower expression levels during the early bud development and after flowering. RcAP3 exhibited high expression levels during buds differentiation in female, male, and hermaphrodite flowers, while RcTM6 showed significant expression in hermaphrodite flowers and very low expression in male and female flowers. During the rapid growth stage of hermaphrodite flowers, RcAP3 was highly expressed in both petals and stamens with minimal differences, whereas RcTM6 showed significantly higher expression in stamens compared to other floral organs. RcAP3 could restore the petal and stamen phenotypes in the ap3-3 mutant of Arabidopsis, while overexpression of RcTM6 resulted in shortened petals, stamens, and aborted ovaries in Arabidopsis. Functional differentiation exists between the AP3/DEF subfamily homologous genes, RcAP3 and RcTM6. RcAP3 promotes petal and stamen development, while RcTM6 inhibits stamen development. These findings provide a foundation for further research on the molecular mechanisms underlying sex differentiation in R. chinensis.

In this study, the chloroplast genomes from 19 species (11 genera) in Oleaceae were compared to reveal the general characteristics and structural variations. The chloroplast genome sizes in Oleaceae were 154-165 kb, and the differences were mainly caused by the length of large single-copy regions. The chloroplast genome sizes of 3 species from the genus Jasminum differed greatly from that for other species; in addition, the introns from the clpP and accD genes were lost in Jasminum. Synteny analyses showed several gene rearrangements in 3 Jasminum species that were probably caused by inversions. The boundary genes between IRb/small single copy (SSC) and SSC/IRa regions in 3 Jasminum species differed from others. Repeat sequences and simple sequence repeat detection demonstrated that Jasminum had significant differences in repeat number and repeat length as compared with other genera. On the basis of shared protein-coding genes among 19 species, Abeliophyllum distichum and Forsythia suspensa were the early-diverging clades in Oleaceae.

The evolution of gene composition of a species is a highly dynamic process, wherein lineage- and species-specific genes originated relatively recently are continuously integrated into the original gene network of older genes. These young genes play important roles in shaping the genome architecture, thereby leading to improved adaptation for organisms. Gene duplication and de novo origination of new genes are two ways to create new genes, causing different gene families with various copy numbers. To what extent and how the evolutionary pattern of genes depends on the timing of gene origination are still largely unexplored in soybean. In this study, we selected 19 representative angiosperms and analyzed the potential relations of the gene content dynamics with the origination of soybean (Glycine max) genes. Using the gene emergence approach, we found that 58.7% of soybean genes could be dated to ~150 million years ago and 21.7% orphan genes had recently originated. As expected, in comparison with young genes, older genes tend to be subjected to stronger purifying selection and were more conserved. In addition, older genes featured higher expression levels and were more likely to undergo alternative splicing. Furthermore, genes with different copy numbers showed a difference in these aspects. These findings may help understand the evolutionary models of genes with different ages.

Increasing nitrogen deposition influences carbon sequestration in grassland ecosystems, but we have no consistent results on how it impacts the exchange of CO₂ at the ecosystem level. As well, the impact of different types of N fertilizers and rates of N increase are not clear yet. This study aimed to evaluate the effect of N addition on ecosystem CO₂ exchange and was performed in a meadow steppe in Erguna, Inner Mongolia. A field experiment compared two types of N fertilizers (urea and slow-release urea) with five N addition rates (0, 5.0, 10.0, 20.0 and 50.0 g N·m^-2·a^-1). At the start and middle stage of the growing season, N addition had weak and inhibitive effects on ecosystem CO₂ exchange when precipitation was low, and significantly increased ecosystem CO₂ exchange in the late growing season when precipitation was high. Both net ecosystem CO₂ exchange and gross ecosystem photosynthesis increased significantly with N addition rate but showed a tendency of saturation when the N addition rate reached 10 g N·m^-2·a^-1. The two types of N fertilizers resulted in slightly different responses of ecosystem CO₂ exchange: slow-release urea had a stronger positive effect at 5 g N·m^-2·a^-1 with no significant difference at other addition rates. Our study suggests that increasing N deposition has significant effects on carbon assimilation in this semi-arid grassland, but the direction and magnitude of effects are strongly affected by seasonal pattern and amount of precipitation. The effects of different types of N fertilizers (i.e., urea and slow-release urea) on ecosystem CO₂ exchange may differ.