Abstract:In order to strengthen the protection of krummholz in Mulinzi Nature Reserve, its community structure and species diversity were analyzed by means of sample site survey. The results showed that there were 53 species of woody plants belonging 19 families 31 genera. Quercus glauca was dominant species, and Fagaceae and Ericaceae were dominant family in the community. Shannon-Wiener diversity index, Simpson dominance index and Pielou evenness index were 1.411, 0.559 and 0.522, respectively, indicating that the diversity of the community was low, and most plants were eliminated by the environment during succession. The community flora had an ancient origin, was deeply influenced by tropical flora with temperate character, showing obvious transition characteristics from subtropical to temperate zone. The diameter class structure of the community showed an inverted “J” type distribution, and the natural regeneration was good. The dominant species Q. glauca had a similar diameter class structure to the community, and occupied a dominant position in the succession process. Therefore, it would provide a theoretical basis for the protection, scientific management and later construction of the moss dwarf forest on the top of the mountain.

Abstract:In order to understand the differences of volatile components among different Begonia species, the volatile components from male flowers of Begonia kui, B. ornithophylla and B. barsalouxiae were determined and analyzed by headspace solid-phase microextraction-gas chromatography-mass spectrometry. The results showed that 97 volatile components were identified from three kinds of Begonia flowers, among which 30 were from B. kui, mainly heterocyclic compounds, did 56 and 44 from B. ornithophylla and B. barsalouxiae, respectively, most of them were alcohols. Principal component analysis (PCA) showed that there are obvious differences in the main aroma components of three Begonias. There were 15 key floral components screened out by partial least square discriminant analysis (PLS-DA), it was inferred that the aromas of B. kui were wax and balm type, that of B. ornithophylla were citrus type, and that of B. barsalouxiae were floral type. Therefore, the types and contents of main volatile components and main aroma substances of different Begonias species had great differences. Floral fragrances were formed by the interaction of various volatiles, and the aroma type is determined by the volatiles with a higher odor value.

Abstract:In order to understand the effects of salt stress on the growth of Baccaurea ramiflora seedlings, the physiological mechanism of stress resistance were studied treated with different soil salt concentrations (0.05%, 0.1%, 0.15% and 0.2%). The results showed that salt stress stimulated the adaptability of B. ramiflora seedlings, especially at low salt concentration (0.05%), soluble sugar content and peroxidase activity increased significantly. When the salt concentration reached 0.1%, the soluble protein content increased significantly. The content of malondialdehyde increased significantly at 0.15% salt concentration. The content of free proline and flavonoids showed significant accumulation at 0.2% salt concentration. In the initial phase (1st week) of salt treatment, peroxidase activity responded rapidly, and other indicators changed significantly after 2 weeks. Some indexes, such as free proline and soluble protein contents and peroxidase activity, increased at first and then decreased with the treatment time. So, it was of great significance for breeding salt-tolerance of B. ramiflora and developing salt-tolerant crops.

Abstract:Flavonoids play an important role in plant resistance to low temperature stress. To reveal the effects of low temperature on flavonoid synthesis in leaves of Phyllostachys edulis, the content of flavonoid in leaves of bamboo seedlings at different growth stages and under low temperature stress was determined by spectrophoto- metric method, the key enzyme genes of early biosynthesis of flavonoid in bamboo were identified by bioinfor- matics methods and their expression patterns were analyzed using qPCR. The results showed that the flavonoid content increased at first and then decreased, while that in the functional leaves increased under low temperature and reached significant level at 8 hours. There were a total of 29 members, belonging to three gene families, involved in early biosynthesis of flavonoid in P. edulis, including 20 chalcone synthase genes (PeCHSs), eight chalcone isomerase genes (PeCHIs) and one flavanone-3-hydroxylase gene (PeF3H1), the promoters of these genes all contained regulatory elements in response to low temperature and other abiotic stress responses. The PeCHSs tended to be expressed in roots and leaves, while PeCHIs expressed constitutively. Only the expression trend of PeCHS1 was consistent with the content of flavonoid in P. edulis leaves at different growth stages, while six key enzyme genes (3 PeCHSs, 2 PeCHIs and PeF3H1) were upregulated continuously in functional leaves under low temperature, which was consistent with the change trend of flavonoid content. Therefore, Phyllostachys edulis might respond to low temperature stress by increasing the expression of genes involved in early biosynthesis of flavonoid.

Abstract:In order to understand the main volatile components of Dendrobium flowers at full bloom stage, the volatile components from flowers of D. thyrsiflorum, D. tortile, D. chrysotoxum and D. densiflorum were determined by solid phase microextraction (SPME) and gas chromatography coupled with mass spectrometry (GC-MS). The results showed that there were 70 volatile components identified in 4 Dendrobium flowers, including 8 types of esters, alcohols, phenols, ketones, alkanes, alkenes, aldehydes and others, among which alkenes was the main volatile component with the highest content. The main aromatic constituent was caryophyllene in D. thyrsiflorum and D. densiflorum with relative contents of 0.46 and 6.91 μg/(g·h), respectively, and acetic acid [6.11 μg/(g·h)] in D. tortile; and β-ocimene [5.23 μg/(g·h)] in D. chrysotoxum. Thus, it was helpful to evaluate and screen valuable germplasm resources of Dendrobium, and provide reference for the cultivation of aromatic Dendrobium species and the development and utilization of orchid essential oil.

Abstract:In order to elucidate the mutation mechanism of leaf color mutation ofAristaloe aristata, the phenotypic characteristics, leaf ultrastructure, photosynthetic pigment content, chlorophyll fluorescence parameters and metabolomics between leaf color mutant ‘MT-1’ and normal leaf color germplasm ‘WT-18’ were compared. The results showed that compared with ‘WT-18’, the mutant ‘MT-1’ exhibited yellow strips from young leaves, and the plant type became smaller and the growth was slower. The number of stomata became less and small, and the shape changed from rectangle to square. The number of chloroplasts and internal lamella decreased, and the volume decreased obviously. The contents of photosynthetic pigments, including chlorophyll a, chlorophyll b and carotenoids, and chlorophyll fluorescence dynamic parameters (Fo, Fm, Fv/Fm, ФPSⅡ, qP, qN and ETR) decreased significantly. The metabolites of ‘MT-1’ and ‘WT-18’ were significantly different. The KEGG metabolic pathway analysis showed that most of the different metabolites were enriched in amino acid metabolism, glucose metabolism, lipid metabolism, nucleic acid metabolism, secondary metabolite biosynthesis, and other pathways. Therefore, the changes in chloroplast related genes might be an important cause of leaf chlorosis mutation.

Abstract:Iris narcissiflora is an endemic herb to western Sichuan Province, China, its current distribution range has been severely shrunk, and it was listed as a key national wild protected plant of grade II. However, the understanding of the population status and habitat characteristics of I. narcissiflora is very poor, which is not conducive to the study of its endangered mechanism and the formulation of conservation measures. The present distribution range of iris daffodil was investigated in detail to investigate the wild population status and habitat, especially the characteristics of the community. After extensive field surveys, I. narcissiflora was distributed in alpine shrubs or edge of spruce (Picea likiangensis var. rubescens) forests with the altitude of 3 779-4 100 m in Daofu County and Kangding City, Ganzi Prefecture, Sichuan Province, and the populations were small with 28 to 2 100 individuals. Based on current distribution, I. narcissiflora is reassessed as endangered (EN) according to the IUCN Threatened Species Assessment criteria B2ab(iii). The species composition of the community with I. narcissiflora was rich, the life type was mainly perennial herbs, with more temperate components. There was a significant negative correlation between species composition similarity and geographical distance between communities. A significantly negative relationship was observed between community similarity and geographic distance. The communities with I. narcissiflora could be divided into four types: spruce forest margin and alpine shrubs with Rhododendron websterianum, R. hippophaeoides and Salix myrtillacea as the dominant species, respectively. The habitat of I. narcissiflora was affected by road construction, grazing, natural succession and global climate change were also potential threats. According to the habitat conditions of different distribution sites, it was suggested to set up conservation areas, take appropriate measures to reduce the expansion of spruce in western Sichuan and the influence of human factors, and to carry out research on ex situ conservation technology.

Abstract:In order to understand the internal causes of endangerment of Michelia shiluensis, the morphological characteristics of flower organs, flowering dynamics and visiting insects were observed, and the pollen germination rate, stigma acceptability and breeding system characteristics were tested. The results showed that the stamen group and pistil group naturally form spatial isolation during flowering, and the perianth plate bends laterally to form a spherical space to protect the stamen group. The pistil stalk continues to extend, pushing the pistil out of the stamen and perianth. The main flower-visiting and pollinating insect of the nurseries are Apis mellifera. Stigma acceptability was strongest in stages VI and VII when the perianth was open to 50% of the maximum diameter. The pollen activity of stage VI was also the highest, and the germination rate in vitro was (66.96±11.28)%. The same flower or cross-flower pollination of the same plant could not bear fruit, but the fruit rate of cross-pollination was 100%. Therefore, Michelia shiluensis is a strictly hetero-pollinated plant, with outbreeding and self-incompatibility, and there is no apomixes, and there is also reproductive isolation with other species of Michelia. The dynamic changes in perianth and pistillation groups of M. shiluensis revealed the biological mechanism of cleverly avoiding self-mating.

Abstract:Primulina liangshengyui R. F. Li & L. Ding, a new species of Gesneriaceae from the limestone of Guangxi, China is described and illustrated. It resembles P. minutimaculata (D. Fang & W. T. Wang) Yin Z. Wang, but can be easily distinguished by a combination of characters, especially in its leaf blades both sides very short white strigillose; bracts adaxially glabrous, abaxially densely white strigillose; calyx lobes both sides densely glandular puberulent; corolla tube purple and gradually fading to white at the base; filaments glandular puberulent. There is only one population with less 500 mature individuals at the type locality. Thus, this species was provisionally assessed as Vulnerable Endangered [VU D2] by using IUCN criteria. Further, supplemented and described of floral morphology of P. minutimaculata is also appended, based on plenty of specimens with flowers and field works, and especially according to living plant in bloom.

Abstract:Leaf functional traits can reflect the adaptation strategies of plant to environment. Based on the sample survey, six wild Rosa anemoniflora communities at different altitude in Yanping District, Fujian Province were selected to study the effects of environment factors on leaf functional traits by using coefficient of variation, Pearson correlation analysis and redundancy analysis. The results showed that the habitat heterogeneity of R. anemoniflora communities was strong, the CV of soil factors under different environment ranged from 9.44% to 122.28%, among which soil pH was the smallest, and soil available phosphorus content was the largest. There are significant differences among soil factor indexes under different environment. The soil pH, contents of organic matter, total nitrogen (N), phosphorus (P) and potassium (K) and available nitrogen (AN), phosphorus (AP) and potassium (AK) were high in the middle altitude areas, and the soil stoichiometric ratio was low, while the soil moisture content and soil stoichiometric ratio were the highest in the high altitude areas. Under different environment, the CV of leaf functional traits of R. anemoniflora ranged from 2.49% to 97.58%, among which leaf water content was the smallest, and the specific leaf weight was the largest. Along the altitude, the contents of P, K, calcium (Ca) and magnesium (Mg) in leaves showed an increasing trend, indicating that the diversity of leaf functional traits was abundant, and had strong adaptability to heterogeneous habitats. Pearson correlation analysis showed that the dry matter content was significantly positively correlated with Ca content in leaves, and the contents of K and Mg were negatively correlated with C/N and N/P in leaves. Rosa anemoniflora at high altitude could increase stress resistance by improving the absorption of K, Ca and Mg to cope with habitat changes. The redundancy analysis showed that soil AK and water content were the main driving factors of leaf functional trait change with environment. Therefore, it was suggested that the leaf of R. anemoniflora adapted to the changes of altitude and habitat through functional trait variation and trait combination. The study on the functional traits of R. anemoniflora leaves and their relationship with environment factors would help to understand the impact of small-scale environmental changes on plant variation, and provide theoretical guidance for the conservation, development and genetic improvement of wild resources of R. anemoniflora.