Search Results (3)

Pteroceltis tatarinowii Maxim is a famous paper-making tree endemic to China with a wide distribution. Leaves of this tree growing in different habitats show a certain plasticity, which is important for their ecological adaption. Here, the photosynthesis ability, hydraulic properties, and anatomy of P. tatarinowii leaves from a limestone forest (Langya Mountain) and a cultivated forest (Xiaoling Village) in Anhui province were compared. The results showed that leaves from Xiaoling Village had higher net photosynthesis rate and hydraulic conductivity, which were closely related to their higher vein density, stomatal density and palisade tissue thickness than leaves from Langya Mountain. However, lower leaf water potentials at turgor loss point and at 50% loss of conductivity, as well as a higher leaf hardness, for Langya Mountain leaves indicated their higher hydraulic safety and drought resistance than those of leaves from Xiaoling Village. This study reveals a hydraulic trade-off between efficiency and safety for P. tatarinowii leaves growing in distinct habitats. Further studies should include more habitats and different vegetation communities to clarify the ecological adaption so as to provide a scientific basis for the protection of this species. Full article

In nature, many different factors cause plants to develop variegated leaves. To explore the mechanism of variegated leaf formation in Pteroceltis tatarinowii, a mutant variety (‘Jinyuyuan’), which was induced by ethylmethylsulfone, was selected, and its morphological structure, physiology, biochemistry, transcription and metabolism were analysed. According to differences in colour values, the colours were divided into two regions: a green region and a yellow-green region. The chlorophyll content of the two regions was significantly different. Moreover, the yellow-green regions of the leaves were significantly thinner than the green regions. The chloroplast ultrastructure in the yellow-green region revealed small chloroplasts, large vacuoles, small starch grains, obviously increased numbers of osmophilic grains, loose lamellae of the inner capsule and thin lamellae. Moreover, the yellow-green region was accompanied by oxidative stress, and the activity of the oxidative phosphorylation pathway related to oxidative activity in the transcriptome showed an upward trend. Vitamin B6 and proline contents also increased, indicating that the antioxidant activity of cells in the yellow-green region increased. Transcriptomic and metabolomic analysis showed that the differentially expressed genes (DEGs) related to chlorophyll synthesis and metabolism led to a decrease in the photosynthesis and then a decrease in the assimilation ability and contents of sucrose, starch and other assimilates. Amino acid synthesis and metabolism, lipid synthesis and the activity of metabolic pathways were obviously downregulated, and the contents of differentially accumulated metabolites associated with amino acids and lipids were also reduced. At the same time, 31 out of 32 DEGs involved in the flavonoid synthesis pathway were downregulated, which affected leaf colour. We hypothesized that the variegated leaves of P. tatarinowii ‘Jinyuyuan’ are caused by transcriptional and post-transcriptional regulation. Mutations in pigment and flavonoid synthesis pathway genes and transcription factor genes directly affect both pigment and flavonoid synthesis and degradation rate, which in turn affect carbon assimilation, carbon fixation, related protein synthesis and enzyme activity, lipid synthesis and degradation and the activity of other metabolic pathways, eventually leading to the formation of different colour regions. Full article

Soil nitrogen (N) and phosphorus (P) shortages limit the growth of shrubs, and P shortage limit the growth of trees in karst ecosystems. Changes in fine root functional traits are the important strategies for plants to respond to such nutrient shortages. However, such responses in karst ecosystems are poorly known. To determine the responses of fine root functional traits to soil N and P changes and define their resource-use strategies in the ecosystem, we tested the specific root length (SRL), root tips over the root biomass (RT/RB), and N concentration (N_root) in the fine roots of four plant species (two shrubs (Alchornea trewioides and Ligustrum sinense) and two trees (Celtis biondii and Pteroceltis tatarinowii)) during the dry (January) and the wet (July) season. The results showed that the SRL, RT/RB, and N_root in the fine roots of shrub species were lower than those of tree species, and the three parameters were higher in the wet season than in the dry season. Linear regression models revealed that the SRL, RT/RB, and N_root of overall species increased with increasing soil N and P concentrations and availabilities, and were positively correlated with increasing rhizosphere soil oxalic acid, microbial biomass carbon (C), and the activities of hydrolytic enzymes. In addition, the individual plant species had unique patterns of the three fine root traits that resulted affected by the change of soil nutrients and biochemistry. Thus, the specific root length, root tips over the root biomass, and N concentrations of fine roots were species-specific, affected by seasonal change, and correlated with soil nutrients and biochemistry. Our findings suggests that fine root functional traits increase the ability of plant species to tolerate nutrient shortage in karst ecosystems, and possibly indicated that a P-exploitative strategy in tree species and an N-conservative strategy in shrub species were exhibited. Full article