Subjects: Biology >> Botany >> Applied botany submitted time 2023-07-13 Cooperative journals: 《广西植物》
Abstract： Climate change has been observed to increase the frequency and intensity of drought, which can adversely affect plant growth and development. Therefore, it is crucial to quantify plant xylem resistance to embolism, particularly in the context of global climate change, to study the process of plant response to drought. In this study, we aimed to evaluate the drought tolerance of Rhododendron cultivars and select those with strong drought resistance by using three species of shrub rhododendrons, namely Rhododendron × pulchrum ‘zihe’, Rhododendron × hybridum ‘yangmeihong’ and Rhododendron simsii, as the materials. Optical techniques were used to construct embolism vulnerability curves in petal and leaf tissues and petal and leaf anatomical structural traits were also measured. The correlation between xylem hydraulic function and anatomical structural traits were also analyzed. The results were as follows: (1) The P12, P50 and P88 values (water potential values corresponding to the occurrence of 12%, 50% and 88% embolism) of petals in Rhododendron × pulchrum ‘zihe’, Rhododendron × hybridum ‘yangmeihong’ and Rhododendron simsii were higher than those of leaves. (2) The embolism vulnerability of petal and leaf tissues varied among the three species, and the speed of petal and leaf embolism occurrence did not coincide, which may be an important characteristic of hybridized horticultural flowering plants. (3)The correlation analysis between P50 values and their morphological characteristics showed that the P50 values of leaves were negatively correlated with leaf palisade tissue thickness, and the P50 values of petals were positively correlated with petal thickness. In conclusion, the study suggests that the petal embolism vulnerability of the three shrubs of Rhododendron is higher than that of the leaves, and the plants preferentially sacrifice the petals to protect the leaves under drought stress. Furthermore, the embolism vulnerability may be related to the leaf palisade tissue thickness and petal thickness. Our findings provide a scientific basis for selecting and configuring tree species of Rhododendron plants in arid areas, and lay the foundation for screening and cultivating drought-resistant Rhododendron varieties.
Subjects: Biology >> Botany >> Applied botany submitted time 2022-02-14 Cooperative journals: 《广西植物》
Abstract： In order to analyze the differences of metabolites and their pathways from flower opening to withering of Rhododendron delavayi, we used LC-MS/MS material separation and identification technique to non-targeted the chemical components of bud stage, dehiscence stage, pollination stage, blooming stage, senescence stage and withering stage. The results were as follows: (1) A total of 973 kinds of metabolites were detected, mainly including flavonoids, organic acids, phenolic acids, amino acids and their derivatives, lipids, alkaloids and so on. (2) Principal component analysis (PCA) shows that there were differences in metabolites among samples. Combined with orthogonal partial least squares discriminant analysis (OPLS-DA), P value of t-test and fold change (Fc) of univariate analysis, differential metabolites (VIP > 1, P < 0.05, Fc > 2 or Fc < 0.5) were screened out, involving 591 species, the quantity and expression of differential metabolites increased significantly after the Rhododendron delavayi flower stage entered the senescence stage and the withering stage, in which the expression of differential metabolites from bud stage to dehiscence stage was mainly down-regulated, while the expression of differential metabolites was mainly up-regulated after entering senescence stage and withering stage. (3) 68 differential metabolic pathways were annotated by KEGG, of which 3 pathways were significantly enriched with differential metabolites (P < 0.01), including phenylpropanoids biosynthesis, plant hormone biosynthesis and flavonoid biosynthesis. (4) Based on the analysis of biosynthetic pathways of phenylpropanoids, flavonoids and other effective components, 10 kinds of differential metabolites were screened from flowering to withering of Rhododendron delavayi, including L-phenylalanine, trans-cinnamic acid, chalcone, naringenin, p-coumaroyl shikimic acid, ferulic acid, coniferyl alcohol, sinapic acid, syringin and quercetin. In addition, the differential metabolites of effective components showed that phenylpropanoids biosynthesis and metabolism activities gradually increased with the development of Rhododendron delavayi, while flavonoid biosynthesis gradually decreased. These key differential metabolites may play an important role in regulating the development of Rhododendron delavayi. This research provides a metabonomic basis for the study of effective components in the metabolic pathway during the flowering and withering process of Rhododendron delavayi, and provides a reference for the further study of the molecular mechanism of flowering regulation of Rhododendron delavayi.
Subjects: Biology >> Botany >> Applied botany submitted time 2019-02-25 Cooperative journals: 《广西植物》
Abstract：随着全球气候变化加重，干旱强度和持续时间逐渐增加，严重影响植物生长和作物产量。喀斯特为典型的干旱和高钙生境，植物叶片富集大量的草酸钙晶体，而该晶体与植物的耐旱性之间的关系并不清楚。该文以喀斯特适生植物堇菜（Viola verecumda）为材料，土壤进行自然干旱，分析堇菜叶片的草酸钙晶体变化特征与水分之间的关系。结果表明，在土壤自然干旱条件下，堇菜主要通过细胞内束缚水的游离，维持细胞内水分平衡；而在干旱后期，叶片通过关闭气孔，将部分自由水转变为束缚水，防止水分流失。此外，草酸钙晶体的数量与束缚水含量具有极其显著的强正相关线性回归关系（r=0.825 3，P<0.000 1），意味着草酸钙晶体担当主要的束缚水物质。因此，堇菜植物在耐旱过程中可能协调草酸钙晶体和气孔的生理行为忍耐干旱胁迫。
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