Abstract:As a highly dangerous alien species, Mikania micrantha has become a serious threat to the ecosystem health and biodiversity of invasive sites. In order to effectively control its invasion, and grasp its spatial distribution and dynamic change, its distribution in Dehong Prefecture, Yunnan Province was extracted by deep learning (DL), support vector machine (SVM) and random forest (RF) methods based on UAV hyperspectral data. The results showed that three methods could effectively extract the distribution of M. micrantha, in which DL method had the best extraction effect with mapping accuracy and user accuracy of 96.61% and 95.00%, respectively, followed by the RF method with those of 94.83% and 91.67%, and the SVM method with those of 92.45% and 81.67%. All three methods could well extract the concentrated distribution areas of M. micrantha, the methods of DL and RF were better than SVM in identification of fragmented distribution of M. micrantha. Therefore, UAV hyperspectral images would provide supports and basis for the monitoring, early warning and precise control of M. micrantha invasion, which was of great significance to protect the security of local ecosystems.

Abstract:To reveal the mechanisms of changing trend of mycorrhizal tree dominance under the environmental influence of increasing seasonal drought and nitrogen deposition in the lower subtropical monsoon evergreen broad-leaved forest, the hydraulic traits and nutrient traits of three ectomycorrhizal (EM), including Engelhardtia roxburghiana, Castanopsis chinensis and C. fissa, and three arbuscular mycorrhizal (AM) dominant trees, including Aporusa yunnanensis, Syzygium levinei and Craibiodendron scleranthum var. kwangtungense, were measured. The results showed that the leaf water potential at which 50% and 88% hydraulic conductance are lost (P₅₀ and P₈₈) and leaf turgor loss point (Ψ_tlp) of EM trees were lower than those of AM trees, while the sapwood specific hydraulic conductivity (K_S), leaf specific hydraulic conductivity (K_L), photosynthetic nitrogen use efficiency (PNUE) and photosynthetic phosphorus use efficiency (PPUE) of EM trees were higher than those of AM trees. The results suggested that EM trees have stronger drought resistance ability and higher water and nutrient use efficiency compared with AM trees. This might be the physiological mechanism of increasing dominance of EM trees while decreasing dominance of AM trees under the background of increasing drought and nitrogen deposition.

Abstract:To understand the spatial distribution characteristic of diatoms in Aojiang River estuary area, Fujian, surface sediment samples from 13 sites were collected in July 2019, and the relationship between distribution of diatoms and environmental factors was studied. The results showed that there were 114 species of diatoms belonging to 39 genera identified from sediment samples. The abundance of diatoms from estuarine to offshore was firstly decreased and then increased. Cluster analysis showed that the main diatom species could be divided into fresh water assemblage zone and brackish-brackish water assemblage zone. Surface water temperature and salinity were the main environmental variables that affect the distribution of diatoms by canonical correspondence analysis (CCA). The salinity in the estuary area was relatively low, freshwater diatoms, such as Achnanthes biasolettiana, A. delicatula and Aulacoseira granulata were the dominant species. The salinity of northern offshore area of Aojiang River was high, marine diatom Surirella fluminensis was dominant. However, the salinity of southern offshore area was low, the abundance of freshwater diatom Achnanthes delicatula was higher than that in northern area. In addition, it is speculated that there may be some water pollution in estuary and the southern offshore area.

Abstract:Under the background of global warming, to achieve a better understanding about tree growth-climate association in subtropical China, tree-ring width chronologies of Pinus kwangtungensis at different elevations were established based on the standard method of dendrochronology. The relationship between radial growth and climatic factors was studied by response analysis and single-year analysis. The results showed that radial growth of P. kwangtungensis at the altitude of 1 400 m was negatively related to the averaged and maximum temperature in June of the current year, and positively related to precipitation in April of current year. The radial growth at the altitude of 1 200 m was significantly positively correlated with the temperature in March, the average temperature and the lowest temperature in October of last year and current year, negatively correlated with the lowest temperature in July of current year, and significantly positively correlated with the precipitation in November of last year. The redial growth at the altitude of 1 000 m was significantly negatively correlated with the average and maximum temperature in June of current year, the average temperature in January and the lowest temperature in October of last year. Additionally, the precipitation in March, October of last year and current year was positively correlated with radial growth. Temperature and precipitation together affect the growth of P. kwangtungensis in Mangshan. Therefore, the temperature and precipitation at the beginning of the growing season as well as the maximum temperature in summer should be the major climatic factors affecting the radial growth of trees.

Abstract:In order to study the response mechanism of Dongxiang wild rice (Oryza rufipogon) to low temperature stress, its RNA-Seq transcriptional expression profile at seedling stage was studied. The results showed that a total of 10 200 differentially expressed genes (DEGs) under low temperature stress were detected compared with control under normal temperature, among which 5 201 DEGs were up-regulated and 4 999 were down-regulated. There were 426 DEGs located in the reported QTL interval of cold tolerance in rice, and 37 of them were family genes related to cold tolerance regulation. Go functional classification and KEGG metabolic pathway analysis of DEGs indicated that nucleic acid binding transcription factor activity, amino acid biosynthesis and photosynthetic metabolism were involved in the response to low temperature stress. The expression patterns of 12 DEGs, including ABA response protein gene, MYB transcription factor and 40S ribosomal protein SA gene, might be related to low temperature stress response by real-time fluorescence quantitative PCR analysis were consistent with those of RNA-Seq. So, it was suggested that plant hormone transduction pathways and transcription factor-related regulatory genes could play an important role in response to low temperature stress in Dongxiang wild rice seedling stage.

Abstract:In order to explore the effects of environment factors on growth of Caulerpa sertularioides, the changes in growth and chlorophyll fluorescence parameters were studied under different salinity, temperature and light intensity. The results showed that the specific growth rate (SGR), maximum light quantum yield (F_v/F_m), actual photosynthetic efficiency (Yield), electron transfer rate (ETR) and photochemical quenching (qP) increased at first and then decrease with increasing salinity, while non-photochemical quenching (qN) was opposite. The photosynthetic activity and carbon fixation efficiency of the algae under 27.5‰ salinity were the highest, and there were significant difference with those under 25‰ and 30‰ salinity (P<0.05, n=3). The SGR, F_v/F_m, Yield,

ETR and qP of the algae decreased with temperature rising, and qN was opposite. The photosynthetic activity and carbon fixation efficiency of algae under 26℃ were the highest, and there were significant difference with those under 28℃ and 30℃ (P<0.05, n=3). The SGR, F_v/F_m, Yield, ETR and qP of the algae increased at first and then decreased with increment of light intensity, while qN was opposite, and there was slight photoinhibition under 18.75 μmol/(m²·s) light intensity. The growth, photosynthetic activity and carbon fixation efficiency of algae were the highest under 25.00 μmol/(m²·s) light intensity, but no significant difference with those under 18.75 and 27.5 μmol/(m²·s) light intensity (P>0.05, n=3). Therefore, it was suggested that C. sertularioides could grow fast with high photosynthesis ability under the conditions of 27.5‰ salinity, 26℃, and 25.00 μmol/(m²·s) light intensity.

Abstract:In order to select cold-resistant lines of Morinda citrifolia for widen the range of planting, the leaf anatomic structures of eight plants growing in Yuanjiang, Yunnan, were observed by paraffin section method, and the activities of catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), and malondialdehyde (MDA) content were measured, and then, glycerol-3-phosphate acyltransferase (GPAT) activity and GPAT gene expression in cold-resistant lines were quantitatively analyzed. The results showed that the leaves of 4 lines (No. 5, 6, 8, 12) had high ratio of palisade tissue to spongy tissue (P/S) with compact cell structure and low porosity, showing a certain cold resistance. The activities of CAT, POD, and SOD of No. 5 leaves were high, and the content of MDA was low after treated at low temperature, indicating that No. 5 was a cold-resistant line. After low temperature treatment, the GPAT activity and GPAT gene expression in No. 5 were higher than those in other plants. Therefore, the cold resistance of M. citrifolia leaves was improved by increasing P/S and cell structure tightness, as well as the rapid response of GPAT gene.

Abstract:To screen out molecular markers suitable for identification of Phytophthora capsici resistant pepper in Chongqing, the screening efficiency of 12 molecular makers for Phytophthora blight resistance was studied in 63 processed pepper (Capsicum annuum) germplasms in Chongqing. The results showed that there were no different amplification bands of 7 markers among the pepper germplasms, and the amplification results of 2 markers were unstable. Only 3 markers, such as ZL6203, ZL6726 and E73, could amplify different bands among pepper germplasms. For ZL6203, the efficiency of screening high resistant, resistant and medium resistant materials was 87.50%, 77.78% and 63.64%, respectively. For ZL6726, the efficiency of screening resistant and susceptible materials was 100.00% and 66.67%, respectively, and for E73, the efficiency of screening resistant and high resistant materials was 77.78% and 62.50%, respectively. Therefore, the screening efficiency of the same molecular marker for different resistance materials was quite different. ZL6203, ZL6726 and E73 markers were suitable for identification of Phytophthora blight resistant of processed pepper in Chongqing.

Abstract:The aim was to explore the genetic background of tea (Camellia sinensis) germplasm for accelerate the breeding of new varieties, the agronomic traits of 19 tea germplasms were observed, and the genetic diversity were analyzed by using SSR markers. The results showed that the new lines 1001 (‘chunlv 2’), 1017 and 46-6 were extra early cultivars, which germination stage was earlier more than 10 days than that of control (‘Fudingdabai’). Except 1001 line (‘chunlv2’) was small tree, the others were shrubs. The leaf shape of most new cultivars was long ellipse, except that 1017, 1011 and 1012 were circular or nearly circular. A total of 231 alleles were amplified from 19 tea germplasms by 48 SSR primers, with an average of 4.8 alleles per SSR. The polymorphism information content (PIC) ranged from 0.14 to 0.85 with an average of 0.55. The PIC of 28 pairs of primers was more than 0.55, accounting for 58.33% to the total of primers. The cluster analysis indicated that 27 tea germplasms could be divided into 4 categories at the genetic distance of 0.32, the first category included lines 1009, ‘Huangmeigui’, ‘Huangdan’ and ‘Huangguanyin’; the second category had 16 lines, such as 1011, 1008, and 1014, etc; the third category had ‘Fudingdabai’, ‘Fuyun 6’, 1017, 1019 and 1015; and the fourth category had 1001 and ‘Zaochunhao’. Therefore, these provide germplasm resources for breeding of new tea varieties.

Abstract:In order to explore the genetic diversity and geographical origin of Amomum tsaoko, the genetic variation of A. tsaoko and A. paratsaoko in 8 SSR loci was studied. The results showed that there was 149 and 101 alleles were detected at 8 SSR loci from 20 populations of A. tsaoko and 5 populations of A. paratsaoko respectively, among which 44, 59 were unique alleles. Variance analysis (AMOVA) showed that only 10.43% of genetic variation existed between two species, 8.66% between populations, and 80.91% within populations (P<0.01). The total genetic differentiation of A. tsaoko was moderate (0.05 ≤ F_st ≤ 0.15), and A. paratsaoko was high (0.15 ≤ F_st ≤ 0.25). The genetic differentiation of the two species increased under SMM model (F_st<P_st). Therefore, the genetic diversity of two species shared the same ancestry, and it was possible that the existing genetic differentiation pattern had been formed by the accumulation of mutations after lineage sorting through random genetic drift. So, Maguan and Pingbian areas around Dawei Mountain might be the geographical origin center of A. tsaoko cultivation.

Abstract:To understand the key enzyme functions of polysaccharide biosynthesis pathway in Alpinia oxyphylla, the polysaccharides contents in stems, leaves and fruits and monosaccharide composition were studied, and the expression pattern of key enzyme genes involved in the biosynthetic pathway of polysaccharide was analyzed by real-time quantitative polymerase chain reaction (RT-qPCR). The results showed that the polysaccharides contents in different tissues was in the order of fruit > leaf > stem. The polysaccharide was consist of glucose, xylose, mannose, galactose and arabinose. A total of 47 690 unigenes were obtained from A. oxyphylla transcriptome database, of which 31 892 were annotated in NR, Swiss-Prot, KEGG, COG, KOG, GO and Pfam databases. Among them, 208 of unigenes encoding 18 enzymes were involved in the biosynthesis of A. oxyphylla polysaccharide. Furthermore, all of 18 selected unigenes were expressed in stems, leaves and fruits, of which 14 unigenes showed the highest expression in fruit. Interestingly, two genes, encoding glycosyltransferase and UDP glucose pyrophosphorylase, exhibited the highest expression, and their expressions were consistent with the glucose content in different tissues of A. oxyphylla.

Abstract:Ophiorrhiza gracilis Kurz was reported from China by several authors previously. Relevant specimen examination and field investigations revealed that it is actually a misidentification of O. caudipetala, which is known to be only distributed in India. Thus, its new record for the flora of China is reported here. Ophiorrhiza caudipetala can be distinguished from other species of the genus in China by its leaves usually in distinctly unequal pairs and corolla lobes with 0.6-1 mm long dorsal horns.

Abstract:The floral morphology of Vaccinium foetidissimum H. Lév. & Vaniot, an endemic species of Ericaceae from China, is firstly described in this paper. The differences between this species and its allies were also discussed in the light of new morphological data.

Abstract:In order to clarify the distribution of quantitative traits of Angelica biserrata, fourteen quantitative traits of 6 A. biserrata germplasms were measured and analyzed. The results showed that there were significant differences of 8 quantitative traits among 6 resources, and 6 quantitative traits had not significant differences. The variation coefficient of 14 quantitative traits ranged from 6.47% to 33.34%, in which the largest was leaf area, and the smallest was the number of replicates of compound leaves. The distribution of 13 quantitative traits conform to the normal distribution except the number of replicates of compound leaves. There was significant positive correlation among leaf width, leaf length, leaf area and leaf circumference with correlation coefficients of 0.568-0.925, and those among other quantitative traits were all lower than 0.560. The principal component analysis showed that 10 quantitative traits played a major decisive role in more two principal components. Five quantitative traits, including multiple leaf circle number, leaf circumference, leaf area, leaf length and leaf order number were removed, the probability grading showed that eight quantitative traits were divided into 5 continuous distributions classification, 1 quantitative trait into 3 continuous distribution classifications.

Abstract:In order to improve the comprehensive utilization rate of the by-products of guava (Psidium guajava), the biological activities and phenolic constituents of extracts from 4 cultivars (‘Zhenzhu’, ‘Shuimi’, ‘Hongbaoshi’, ‘Xigua’) of guava were studied. The contents of total phenols and flavonoids were determined, then the correlations between the contents of phenols and flavonoids with biological activities were analyzed, including the scavenging abilities on DPPH·, ABTS⁺, HO· free radicals, and the α-glucosidase inhibitory activity. Furthermore, the phenolic constituents of extracts were identified by ultra-high performance liquid chromatography and the triple-quadrupole tandem mass spectrometry (UPLC-MS/MS). The results showed that the contents of total phenols and flavonoids, the free radicals scavenging abilities and α-glucosidase inhibitory activity in leaves of 4 cultivars were significantly higher than those in young fruits, ‘Zhenzhu’ leaf had the highest content of total phenols as well as the most potent free radicals scavenging abilities and α-glucosidase inhibitory activity. Correlation analysis revealed that the contents of phenols and flavonoids were significantly positively correlated with the scavenging abilities towards DPPH·, ABTS⁺, HO· free radicals (P<0.01), as well as the α-glucosidase inhibitory activity (P<0.05). UPLC-MS/MS analysis showed that the contents of quercetin-3-O-glucoside, hyperoside, ellagic acid and myricitrin in leaves of 4 cultivars were high, and most of the constituents found in leaves except ellagic acid also existed in the young fruits, and the contents in leaves were higher than those in young fruits. Therefore, ‘Zhenzhu’ guava leaf could be a good resource for developing natural antioxidant and α-glucosidase inhibitor among 4 cultivars.