Journal of Plant Research最新文献

The physical filtering of pollinators is an important factor influencing pollination effectiveness. This study explored the potential functions of dense hairs that completely obstruct the entrance of floral tube in Marsdenia tinctoria by characterizing the flowers of this species, as well as its pollinators and their behavior. The corolla was white upon blooming in the morning, then turned yellow at night, and the flower finally dropped by the third morning. The hairs tended to be disheveled in yellow-petaled flowers. Pollination success increased with floral age. Direct observations of flowers in natural M. tinctoria populations over a period of 32 h recorded 126 visitors, of which 70% were wasps. We observed pollinia attached to the mouthparts of wasps, carpenter bees, and honeybees, but not to those of butterflies, moths, flies, or ants. Detailed examination of insect mouthparts and floral morphology indicated that insect visitors that acted as pollinators had mouthparts longer than the floral tubes, equipped with hairs to which pollinia could attach. The mouthparts of potter wasps were often covered with pollinaria, carrying on average 30-75 pollinia. The dense floral hairs were penetrated by large-bodied visitors, and blocked smaller visitors. Disturbance of these floral hairs allowed smaller insects to access nectar, suggesting that the hairs function in preventing nectar theft by smaller insects. This study presents the first case of wasp pollination in the genus Marsdenia and provides insights into the potential function of its dense floral hairs, a synapomorphy of this genus, in filtering floral visitors.

Water conservation in fine roots can be important for the adaptation of trees to cold, nutrient-poor ecosystems. Although pressure-volume (p-v) curve traits are commonly used to assess leaf water conservation, little is known about their intraspecific variation in fine roots and their association with root functional traits, such as morphology and chemistry. Here, we aimed to determine the p-v curve traits of Betula ermanii and Abies mariesii fine roots at 2,000 and 2,500 m elevations and explore their intraspecific variation with root morphological and chemical traits in a subalpine forest. Turgor loss point (π_tlp), relative water content at π_tlp, osmotic potential at full hydration, and capacitance at full turgor (C_ft) were evaluated as p-v curve traits. Additionally, root diameter, specific root length, and root tissue density (RTD) were assessed as morphological traits, and nitrogen (N) content was measured as a chemical trait. For A mariesii roots, the C_ft was lower, and π_tlp was more negative at 2,500 m than at 2,000 m. The p-v curve traits of B ermanii roots remained unchanged with elevation. There were strong correlations between RTD and π_tlp and between N content and π_tlp and C_ft, especially for A. mariesii. These results indicated A. mariesii adjusted p-v curve traits with RTD and N content and achieved water conservation in fine roots at higher elevations. The p-v curve traits, particularly π_tlp and C_ft, reflected diverse tree strategies for environmental acclimation with fine-root carbon economy. Our findings highlighted the importance of adjusting water relation traits for acclimation to cold and nutrient-poor subalpine regions, particularly for evergreen coniferous species. The p-v curve traits revealed diverse fine-root water relation traits as a basis for water conservation capacity by preserving root function under stress conditions and enabling prolonged resource acquisition in a subalpine forest.

The summer heat is a vital factor limiting the introduction of relatively large-leaf Rhododendron plants to low-altitude areas, making it crucial to evaluate the resistance of different germplasm to summer heat. A pot experiment was conducted in 2023 to investigate the temporal changes in the photosynthetic characteristics, physiological and biochemical characteristics, and chlorophyll fluorescence characteristics of 14 representative relatively large-leaf Rhododendron germplasm. The results showed the R. irroratum and 'Hotspur Red' exhibited the highest heat damage index (HDI), while R. jiulongshanense and 'Moser Maroon' had the lowest HDI among the 14 Rhododendron germplasm. The photosynthesis rate and F_v/F_m (maximum photochemical efficiency) initially decreased and then recovered in all germplasm except R. irroratum. In contrast, the leaf transpiration rate, stomatal conductance, and chlorophyll content gradually increased. Hydrogen peroxide concentration first decreased and then increased, while malondialdehyde concentration initially increased and then decreased. Additionally, the superoxide anion content gradually increased. The activities of superoxide dismutase, peroxidase, and catalase (CAT) initially increased and then decreased. The HDI was positively correlated with CAT activity (r = 0.28, P < 0.05) but negatively correlated with photosynthesis rate (r = -0.26, P < 0.05), leaf transpiration rate (r = -0.27, P < 0.05), and F_v/F_m (r = -0.43, P < 0.001). Variation in summer heat resistance, as indicated by HDI, was observed among the 14 Rhododendron germplasm. This heat resistance was mainly associated with leaf transpiration rate and F_v/F_m. The indirect role of antioxidant enzymes in maintaining reactive oxygen species homeostasis in summer heat resistance was observed. The results provide a reference for introducing and cultivating relatively large-leaf Rhododendron plants to low-altitude areas.

Pregnane derivatives such as pregnenolone or progesterone and many other metabolites are important in mammals where many of them act as hormones including sexual hormones. Much less is known about the presence and functions of pregnane derivatives in plants. The main objectives of this work were (1) to determine the presence of pregnane derivatives in winter wheat (2) verify if there are changes of concentration of pregnane derivatives during wheat growth/development with special attention to vernalisation process (3) to answer the question of whether selected pregnane derivatives are stimulators of wheat development and whether the potential stimulation of this development is accompanied by the expression of the Vrn1 (Vernalisation1) gene. To the best of our knowledge, this is the first report that demonstrates the presence of pregnenolone and 5α-dihydroprogesterone in the leaves and intact crowns of winter wheat. The levels of some of the pregnane derivatives changed during plant growth/development, it was demonstrated that pregnenolone, pregnanolone and 17α-hydroxypregnenolone stimulated wheat development. The changes in the Vrn1 expression are discussed in light of the stimulation of generative development by the pregnane derivatives.

Increased nitrogen deposition significantly impacts invasive plants, leading to population differentiation due to different environmental pressures during expansion. However, various populations respond differently to elevated nitrogen levels. This study explores the responses of central and edge populations of the annual invasive plant Galinsoga quadriradiata to different levels of nitrogen addition. The results indicate that the central population has a stronger need for nitrogen, with nitrogen addition promoting the growth of its aboveground parts, reducing intraspecific competition, and increasing reproductive allocation and total biomass. Specifically, nitrogen addition provides more nutritional resources, easing resource competition among plants, reducing intraspecific competitive pressure, and allowing plants to allocate more energy to growth and reproduction, thereby enhancing their expansion potential. In contrast, the edge populations respond differently to nitrogen. Although nitrogen addition promotes the growth of their underground parts and enhances root development, the impact on aboveground parts is smaller. The enhancement of underground parts helps edge populations better adapt to barren environments, improving their survival and competitive ability in new environments, thus increasing their expansion potential. Overall, the growth impact on edge populations due to nitrogen addition is smaller, possibly indicating they have exceeded their nitrogen limit. The study demonstrates that the degree of population differentiation in invasive plants at different invasion stages is a critical factor in studying their spread potential, aiding in predicting plant invasion trends under climate change and providing theoretical support for formulating targeted management strategies.

Barley (Hordeum vulgare L.) is an important cereal crop used in animal feed, beer brewing, and food production. Waterlogging stress is one of the prominent abiotic stresses that has a significant impact on the yield and quality of barley. Seed germination plays a critical role in the establishment of seedlings and is significantly impacted by the presence of waterlogging stress. However, there is a limited understanding of the regulatory mechanisms of gene expression and metabolic processes in barley during the germination stage under waterlogging stress. This study aimed to investigate the metabolome and transcriptome responses in germinating barley seeds under waterlogging stress. The findings of the study revealed that waterlogging stress sharply decreased seed germination rate and seedling growth. The tolerant genotype (LLZDM) exhibited higher levels of antioxidase activities and lower malondialdehyde (MDA) content in comparison to the sensitive genotype (NN). In addition, waterlogging induced 86 and 85 differentially expressed metabolites (DEMs) in LLZDM and NN, respectively. Concurrently, transcriptome analysis identified 1776 and 839 differentially expressed genes (DEGs) in LLZDM and NN, respectively. Notably, the expression of genes associated with redox reactions, hormone regulation, and other biological processes were altered in response to waterlogging stress. Furthermore, the integrated transcriptomic and metabolomic analyses revealed that the DEGs and DEMs implicated in mitigating waterlogging stress primarily pertained to the regulation of pyruvate metabolism and flavonoid biosynthesis. Moreover, waterlogging might promote flavonoid biosynthesis by regulating 15 flavonoid-related genes and 10 metabolites. The present research provides deeper insights into the overall understanding of waterlogging-tolerant mechanisms in barley during the germination process.

Since photosynthesis is highly sensitive to salinity stress, remote sensing of photosynthetic status is useful for detecting salinity stress during the selection and breeding of salinity-tolerant plants. To do so, photochemical reflectance index (PRI) is a potential measure to detect conversion of the xanthophyll cycle in photosystem II. Raphanus sativus var. raphanistroides is a wild radish species closely related to domesticated radish, and is distributed throughout the coastal regions of Japan, where it is thought to be salt tolerant. In this study, we raised wild and domesticated radishes under various salt conditions and assessed growth, photosynthetic status, and PRI. When grown at mild salt stress (50 mM NaCl), wild radish leaves showed photosynthetic activity levels comparable to control plants, whereas the photosynthetic activity of domesticated radish was suppressed. This result suggests that wild radishes are more salt-tolerant than domesticated radishes. Although photosynthetic rate and the photochemical quantum yield were significantly correlated with PRI in both species, the PRI resolution was insufficient to distinguish differences in salt tolerance between wild and domesticated radish. Wild radish had a lower maximum quantum yield (Fv/Fm) when grown under moderate salt stress (200 mM NaCl), suggesting chronic photoinhibition. The relationship between non-photochemical quenching (NPQ) and PRI was significant when leaves with chronic photoinhibition were eliminated but this relationship was not significant when they were included. In contrast, the relationship between photosynthesis and PRI was significant regardless of whether leaves displayed chronic photoinhibition or not. We conclude that PRI is useful to detect relatively large reductions in photosynthetic rate under salinity stress, and that care should be taken to evaluate NPQ from PRI.

Calotropis procera (Aiton) W.T. Aiton is a medicinal plant belonging to the family Apocynaceae as a core source of natural cardenolides. Cardiac glycosides (CGs) are steroid derivatives reported to have the ability to regulate cancer cell survival and death through multiple signaling pathways. Earlier stage-specific and wound-responsive accumulation of CGs and their genin units have already been reported. Recent cumulative evidences have implicated stress and defense response signaling in the production of secondary metabolite in plants. In this report, seasonal accumulation of CGs and its genin units have been explored along with their profiling under control vs stress conditions with a significant accumulation using LC-MS/MS. The study showed that Calotropis procera plants efficiently accumulate CGs and genin units in both winter and summer beside rainy season, as well as under thermal and salinity stress. Among the three cardenolides, the calotropagenin was accumulated more than coroglaucigenin and uzarigenin whereas CGs like calotropin, frugoside, uscharidin, uscharin, and asclepin were significantly accumulated in response to heat, cold and NaCl. Comparatively for hormonal treatments like methyl jasmonate and salicylic acid, targeted metabsolites showed upto twofold accumulation. Gene expression analysis of CG biosynthetic genes also validated the accumulation pattern of the targeted metabolite. This targeted metabolites accumulation enhances plant tolerance to adverse conditions. Gene expression analysis supports this strategy, emphasizing the plant's effective stress management. These findings significantly contribute to our understanding of how plants adapt to stress through the accumulation of metabolites, thereby enhancing their tolerance to challenging environmental conditions.

The oxidative damage induced by abiotic stress factors such as salinity, drought, extreme temperatures, heavy metals, pollution, and high irradiance has been studied in Arabidopsis thaliana. Ultra-weak photon emission (UPE) is presented as a signature reflecting the extent of the oxidation process and/or damage. It can be used to predict the physiological state and general health of plants. This study presents an overview of a potential research platform where the technique can be applied. The results presented can aid in providing invaluable information for developing strategies to mitigate abiotic stress in crops by improving plant breeding programs with a focus on enhancing tolerance. This study evaluates the applicability of charged couple device (CCD) imaging in evaluating plant stress and degree of damage and to discuss the advantages and limitations of the claimed non-invasive label-free tool.