Qingfeng Wang’s research while affiliated with Chinese Academy of Sciences and other places

Cissus rotundifolia Lam. is an evergreen climber that mainly distributed in the tropical savannas of eastern Africa with excellent drought resistance. While the mechanism underlying drought stress response in C. rotundifolia remains unknown. In this study, we investigated the transcriptomics and flavonoid metabolomics responses of C. rotundifolia leaves under different drought conditions. We identified a total of 2401 differentially expressed genes (DEGs) in drought-treated leaves. The continuously increasing DEGs were significantly enriched in pathways related to phenylpropanoid biosynthesis, flavonoid biosynthesis, and galactose metabolism. The total flavonoids content were also found increased significantly during drought treatment in the leaves of C. rotundifolia . A total of 57 distinct flavonoids were identified using UPLC-MS/MS. Among them, nine out of ten differentially accumulated metabolites (DAMs) displayed notable accumulation profiles under drought conditions. These DAMs included two flavanols [(-)-Catechin gallate and (-)-gallocatechin gallate], two flavonols (myricetin and astragalin), four flavones (orientin, cynaroside, isoorientin, and vitexin), and one flavanone (naringenin-7-glucoside), indicating their pivotal roles in drought response. Additionally, a DEG with continuously high-expression, annotated flavone synthase ( FLS ) synthesises, and synthetizing myricetin under drought stress was tightly related to additional genes belonging to ABA-signaling genes, stomata movement genes, transcription factors, and protein kinases, these genes were contained Top 10 hub-genes of network constructed all DEGs. The results reflect the significance of FLS and potentially regulatory genes under drought conditions. These findings suggest that flavonoids play a pivotal role in the drought stress response of C. rotundifolia , advancing our understanding of flavonoids accumulation and the transcriptional regulation involved in this process.

Cold tolerance is one of the important traits for grapevine, especially in regions with extremely low temperatures in winter. Vitis amurensis is wild species in the Vitis genus with excellent cold hardiness compared with Vitis vinifera. However, metabolites that contribute to the cold tolerance of V. amurensis remain unknown. Here, the metabolomics of buds from V. amurensis ‘Zuoshan-1’ during cold acclimation (CA) were identified, and cold-sensitive cultivar (V. vinifera ‘Jingzaojing’) was used as the control. The buds were collected in October, November, and December in 2016 and 2018. The cold hardiness of the buds increased during CA in the two grapevines. However, browning was observed only in V. vinifera buds at temperature below −10 °C. Among detected metabolites from buds, 443 metabolites were overlapped between two years. Forty-four and thirty differentially accumulated metabolites (DAMs) were identified in V. amurensis and V. vinifera, respectively. Ten DAMs including monoacylglycerol (MAG, 18 : 2) isomer1, trehalose 6-phosphate, and D-glucose showed identical variations in the two grapevines, indicating conserved CA responses within the Vitis genus. Eighteen DAMs exhibited higher accumulation in V. amurensis than in V. vinifera. Maltotetraose, D-glucoronic acid, L-aspartic acid, azelaic acid, and 4-hydroxybenzoic acid were reported to accumulate during CA in other plants. Enhanced cold tolerance was detected in grapevine leaves with exogenous 5 mmol · L-1 L-aspartic acid and 1% proanthocyanidins. Potential contributions of other DAMs found in V. amurensis such as Cyanidin 3-O-glucoside need to be further elucidated. Thus, eighteen metabolites accumulated in V. amurensis can be used for practical application in improvement of cold resistance in grapevine. Our findings provide new insights into understanding the cold hardiness of V. amurensis. Keywords: grapevine; metabolomics; bud; low temperature; cold hardiness

Medicinal plants play a crucial role in healthcare practices and are an integral part of human society. A comprehensive checklist of medicinal plants is the basis for the risk and protection. Tropical East Africa (TEA) has a high diversity of medicinal plants. This study compiled a comprehensive checklist using published books and literature comprising 2855 medicinal plants spanning 180 families and 1034 genera in TEA. The family with the largest number of medicinal plant species is Fabaceae, followed by Asteraceae and Rubiaceae. The root emerges as the most utilized part in woody medicinal plants, contrasting with herbaceous plants where leaves take precedence. The regions with high diversity of medicinal plants are mainly concentrated in northern and southern Rwanda, western Burundi, western Uganda, central and western Kenya, as well as northeastern and southwestern Tanzania. Priority conservation areas for medicinal plants were identified based on specific species and risk of collection, and included regions of west-central Kenya, northeastern Tanzania, and eastern Burundi. Our research emphasizes the significance of protecting these valuable medicinal plants by proposing corresponding conservation measures. The medicinal plant resources of TEA remain an opportunity for exploration, and the diversity of medicinal plants needs to be further improved.

Cold stress is an adverse environmental factor that limits the growth and productivity of horticulture crops such as grapes (Vitis vinifera). In this study, we identified a grapevine cold-induced basic helix–loop–helix (bHLH) transcription factor (VvbHLH036). Overexpression and CRISPR/Cas9-mediated knockout (KO) of VvbHLH036 enhanced and decreased cold tolerance in grapevine roots, respectively. Transcriptome analysis of VvbHLH036-overexpressed roots identified threonine synthase (VvThrC1) as a potential downstream target of VvbHLH036. We confirmed that VvbHLH036 could bind the VvThrC1 promoter and activate its expression. Both the transcripts of VvThrC1 and the content of threonine were significantly induced in the leaves and roots of grapevine under cold treatment compared to controls. Conversely, these dynamics were significantly suppressed in the roots of CRISPR/Cas9-induced knockout of VvbHLH036. These observations support the regulation of threonine accumulation by VvbHLH036 through VvThrC1 during cold stress in grapevine. Furthermore, overexpression and CRISPR/Cas9-mediated knockout of VvThrC1 also confirmed its role in regulating threonine content and cold tolerance in transgenic roots at low temperature. Exogenous threonine treatment increased cold tolerance and reduced the accumulation of superoxide anions and hydrogen peroxide in grapevine leaves. Together, these findings point to the pivotal role of VvbHLH036 and VvThrC1 in the cold stress response in grapes by regulating threonine biosynthesis.

Cissus quadrangularis is a tetraploid species belonging to the Vitaceae family and is known for the Crassulacean acid metabolism (CAM) pathway in the succulent stem, while the leaves perform C3 photosynthesis. Here, we report a high-quality genome of C. quadrangularis comprising a total size of 679.2Mb which was phased into two subgenomes. Genome annotation identified 51,857 protein-coding genes, while approximately 47.75% of the genome was composed of repetitive sequences. Gene expression ratios of two subgenomes demonstrated that the sub-A genome as the dominant subgenome played the vital role during the drought tolerance. Genome divergence analysis suggests that the tetraploidization event occurred around 8.9 million years ago. Transcriptome data revealed that pathways related to cutin, suberine, and wax metabolism were enriched in the stem during drought treatment, suggesting that these genes contributed to the drought adaption. Additionally, a subset of CAM-related genes displayed diurnal expression patterns in the succulent stems but not in leaves, indicating that stem-biased expression of existing genes contributed to the CAM evolution. Our findings provide insights into the mechanisms of drought adaptation and photosynthesis transition in plants.

Plant terrestrialization (i.e., the transition to a terrestrial environment) is a significant evolutionary event that has been intensively studied. While certain plant lineages, particularly in angiosperms, have re-adapted to freshwater habitats after colonizing terrene, however, the molecular mechanism of the terrestrial-freshwater (T-F) transition remains limited. Here, the basal monocot Araceae was selected as the study object to explore the T-F transition adaptation mechanism by comparative genomic analysis. Our findings revealed that the substitution rates significantly increased in the lineage of freshwater Araceae, which may promote their adaptation to the freshwater habitat. Additionally, 20 gene sets across all four freshwater species displayed signs of positive selection contributing to tissue development and defense responses in freshwater plants. Comparative synteny analysis showed that genes specific to submerged plants were enriched in cellular respiration and photosynthesis. In contrast, floating plants were involved in regulating gene expression, suggesting that gene and genome duplications may provide the original material for plants to adapt to the freshwater environment. Our study provides valuable insights into the genomic aspects of the transition from terrestrial to aquatic environments in Araceae, laying the groundwork for future research in the angiosperm.