Fagus longipetiolata Seemen is a deciduous tree of the Fagus genus in Fagaceae, which is endemic to China. In this study, we successfully sequenced the cp genome of F. longipetiolata, compared the cp genomes of the Fagus genus, and reconstructed the phylogeny of Fagaceae. The results showed that the cp genome of F. longipetiolata was 158,350 bp, including a pair of inverted repeat (IRA and IRB) regions with a length of 25,894 bp each, a large single-copy (LSC) region of 87,671 bp, and a small single-copy (SSC) region of 18,891 bp. The genome encoded 131 unique genes, including 81 protein-coding genes, 37 transfer RNA genes (tRNAs), 8 ribosomal RNA genes (rRNAs), and 5 pseudogenes. In addition, 33 codons and 258 simple sequence repeats (SSRs) were identified. The cp genomes of Fagus were relatively conserved, especially the IR regions, which showed the best conservation, and no inversions or rearrangements were found. The five regions with the largest variations were the rps12, rpl32, ccsA, trnW-CCA, and rps3 genes, which spread over in LSC and SSC. The comparison of gene selection pressure indicated that purifying selection was the main selective pattern maintaining important biological functions in Fagus cp genomes. However, the ndhD, rpoA, and ndhF genes of F. longipetiolata were affected by positive selection. Phylogenetic analysis revealed that F. longipetiolata and F. engleriana formed a close relationship, which partially overlapped in their distribution in China. Our analysis of the cp genome of F. longipetiolata would provide important genetic information for further research into the classification, phylogeny and evolution of Fagus.

Smilax microphylla C. H. Wright is a climbing shrub that can be used for herbal medicine. The complete chloroplast genome sequence of S. microphylla was determined in this study. It is 158,246 bp in length with a GC content of 37.12%, and consists of a pair of inverted repeat (IR) regions of 27,175 bp, a large single copy (LSC) region of 85,229 bp, and a small single copy (SSC) region of 18,667 bp. The genome encoded 132 genes, including 86 protein-coding genes, 38 tRNA genes, and 8 rRNA genes. The phylogenetic analysis showed that S. microphylla is phylogenetically closely related to Smilax china and Smilax nipponica.

Pines have heteroblastic foliage (primary and secondary needles) during seedling stage, but how heteroblastic foliage affects carbon storage and biomass accumulation, contributing to seedling quality, is unclear. We investigated the influences of heteroblastic foliage on photosynthetic physiological characteristics, non-structural carbohydrate (NSC) and biomass accumulation in current-year seedlings; the key factors determining biomass accumulation were mainly determined by principal component screening, Spearman correlation, and path analysis. The results indicated that (1) primary needles have high photosynthetic pigments (chlorophyll a and total chlorophyll), net photosynthetic rates (Pn), the potential maximum photochemical efficiency (Fv/Fm), and leaf instantaneous water use efficiency (WUEi), whereas higher non-photochemical quenching (NPQ) suggested that sudden light increases induce the initiation of quenching mechanism in primary needles; additionally, secondary needles had a lower transpiration rate (Tr), limiting stomata (Ls), and light saturation point. (2) Secondary needles promoted soluble sugar (fructose and glucose) increases in leaves compared to that of primary needles and increased the leaf biomass accumulation (from 47.06% to 54.30%), enhancing the overall ability of photosynthetic organs; additionally, secondary needles can enhance the proportion of starch storage in the roots, and NSC accumulation was significantly increasing in the seedling leaves and roots. (3) Photosynthetic pigments (carotenoids, chlorophyll a, and total chlorophyll) had direct positive effects on primary needle seedling (PNS) biomass and promoted biomass by indirectly increasing soluble sugar synthesis in the stems. The Pn was the main physiological factor determining PNS biomass accumulation. In addition, the WUEi, Ls, and NPQ had direct negative effects on PNS biomass accumulation, inhibiting photosynthesis to limit seedling growth. Considering the functional traits in heteroblastic foliage is necessary when assessing different leaf types of Pinus massoniana (Lamb.) seedlings, in particular those threats implicated in light, water, and temperature relations. Our results can be beneficial to guide the establishment of seedling management and afforestation measures.