Goji berry (Lycium barbarum L.) exposure to elevated CO2 (eCO2) for long periods reduces their sugar and secondary metabolite contents. However, sugar accumulation in fruit depends on photosynthesis and photoassimilate partitioning. This study aimed to explore photosynthesis, sugar content, and sucrose metabolism-related enzyme activities in goji berry leaves and fruits under ambient and eCO2 levels, and identify the genes encoding L. barbarum acid invertase (LBAI), L. barbarum sucrose synthase (LBSS), L. barbarum sucrose phosphate synthase (LBSPS), and L. barbarum neutral invertase (LBNI), based on transcriptome profiling. Further, the characterization of four identified genes was analyzed including subcellular localization and expression patterns. In plants grown under eCO2 for 90 or 120 days, the expression of the above-mentioned genes changed significantly as the photosynthetic rate increased. In addition, leaf and fruit sugar contents decreased, and the activities of four sucrose metabolism-related enzymes increased in leaves, while acid and neutral invertase increased in fruits. Protein sequence analysis demonstrated that LBAI and LBNI contain a conservative structure domain belonging to the glycosyl hydrolases (Glyco_hydro) family, and both LBSS and LBSPS belonging to the sucrose synthase (Sucrose_synth) and glycosyltransferase (Glycos_transf) family. Subcellular localization analysis showed that LBAI, LBNI, and LBSS were all located in the nucleus, plasma membrane, and cytoplasm, while LBSPS was located in the plasma membrane. The expressions of LBAI, LBSPS, and LBNI were high in the stems, whereas LBSS was predominantly expressed in the fruits. Our findings provide fundamental data on photosynthesis and sugar accumulation trends in goji berries under eCO2 exposure.
SUMMARY
Rosemary (Salvia rosmarinus) is considered a sacred plant because of its special fragrance and is commonly used in cooking and traditional medicine. Here, we report a high‐quality chromosome‐level assembly of the S. rosmarinus genome of 1.11 Gb in size; the genome has a scaffold N50 value of 95.5 Mb and contains 40 701 protein‐coding genes. In contrast to other diploid Labiataceae, an independent whole‐genome duplication event occurred in S. rosmarinus at approximately 15 million years ago. Transcriptomic comparison of two S. rosmarinus cultivars with contrasting carnosic acid (CA) content revealed 842 genes significantly positively associated with CA biosynthesis in S. rosmarinus. Many of these genes have been reported to be involved in CA biosynthesis previously, such as genes involved in the mevalonate/methylerythritol phosphate pathways and CYP71‐coding genes. Based on the genomes and these genes, we propose a model of CA biosynthesis in S. rosmarinus. Further, comparative genome analysis of the congeneric species revealed the species‐specific evolution of CA biosynthesis genes. The genes encoding diterpene synthase and the cytochrome P450 (CYP450) family of CA synthesis‐associated genes form a biosynthetic gene cluster (CPSs–KSLs–CYP76AHs) responsible for the synthesis of leaf and root diterpenoids, which are located on S. rosmarinus chromosomes 1 and 2, respectively. Such clustering is also observed in other sage (Salvia) plants, thus suggesting that genes involved in diterpenoid synthesis are conserved in the Labiataceae family. These findings provide new insights into the synthesis of aromatic terpenoids and their regulation.
To research influence of low light on macrophyte growth, seedlings of Vallisneria natans were transplanted into the waters with 5%, 1%, 0.5% and 0.1% full sunlights, respectively. The results show that germination rates are significantly inhibited with the experiment. In first 20 days leaf formation of new plants aren’t inhibited, and their leaf elongation are promoted. Since then, them of old plants and new plants are remarkably inhibited with the experiment. Though maximum photochemical quantum yield (Fv/Fm), relative electron transport rate (ETR) and non-photochemical quenching (NPQ) of old plants reduce significantly on low light conditions, but V. natans still hsa a certain degree of photoasynthetic capacity on the 80th day. Fresh weight ratio of roots and stems increase with decreasing light intensity. However, it exhibits an opposite trend for leaves. Thus, V. natans has a strong ability of low-light (≤1% full sunlight) tolerance.
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