Abstract:In the process of investigating the photosynthesis related genes, we obtained a recessive Arabidopsis thaliana mutant, yellow heart (yh). Compared with the wild type (Col0) A. thaliana, yh mutant appeared a yellow heart phenotype in new leaves. With mapbased cloning strategy, the mutant gene yh was precisely mapped into the 676 kb chromosome interval between the molecular markers INS1_55_342 and INS1_56_34 on chromosome 1. The yh mutant has a 4 base deletion at the splice junction of the 44th intron, which result in a change in the splice site of the intron. RTPCR results have indicated that the expression of yh gene is knock down, and yh mutant is indeed a new allelic mutation in gene At1g64790. Based on study above, yh mutant may provide a new genetic material to explore the chloroplast and leaf development mechanisms.

Abstract:In this study, the flavonoid3′ hydroxylase (F3′H) gene was cloned from Chrysanthemum morifolium color petal mutant CQ17mu by RTPCR. The fulllength open reading frame of the gene was 1 527 bp, encoding 508 amino acids, which was 99% similarity with the known C. morifolium CmF3′H, so it was named CmF3′Ha. Amino acid sequence analysis showed that the protein encoded by CmF3′Ha had a conserved F3′H domain and belonged to P450 super family. Multiple sequence alignment and phylogenetic analysis showed that CmF3′Ha was closely related to F3′H of other Chrysanthemum. Real time PCR analysis showed that the expression level of CmF3′Ha gene in CQ17mu petals was significantly higher than that in CQ17 pink petals, indicating that CmF3′Ha was involved in anthocyanin metabolism in CQ17mu petals. Furthermore, a 1 086 bp promoter sequence of F3′H gene upstream of CQ17mu was obtained by chromosome walking method. Analysis showed that the sequence contained not only core promoter elements such as TATAbox, but also multiple MYB and MYC binding sites, multiple light response elements and hormone response elements. This study proved that the CmF3′Ha gene of C. morifolium was positively correlated with plant anthocyanin accumulation and participated in the anthocyanin synthesis process of color stripe, which provided a theoretical reference for the molecular breeding of C. morifolium.

Abstract:In this study, the cucumber ‘Jinchun No. 2’ cDNA was used as the template, and the key enzyme gene (CsPAO) for chlorophyll degradation (pheophorbide a oxygenase, PAO) of cucumber was cloned by RTPCR method, and the subcellular location was observed and realtime fluorescence was used. Quantitative PCR technology and bioinformatics technology analyzed the expression pattern of CsPAO gene and the characteristics of its encoded protein. The results showed that: (1) CsPAO encodes 545 amino acids, the theoretical isoelectric point is 6.09, and the relative molecular mass of the protein is 61.02 kD. Protein prediction found that cucumber CsPAO is an unstable protein with two protein binding sites and a transmembrane phenomenon. (2) Fluorescence quantitative PCR results show that CsPAO responds to salicylic acid (SA), jasmonic acid (JA) and gibberellin (GA₃), the expression of CsPAO gene under high temperature (42 ℃) and low temperature (4 ℃) treatments, the amount increased significantly and the expression reached the highest, but the dark treatment had no effect on the expression of CsPAO gene; the expression in flowers of cucumber was significantly higher than that of roots, stems, leaves, calyx, whiskers and fruit. (3) The subcellular localization results show that the CsPAO protein is localized in the chloroplast. (4) Phylogenetic tree analysis shows that cucumber CsPAO is closely related to bitter gourd, summer squash, pumpkin and winter squash. The results of this study laid the foundation for further revealing the molecular mechanism of cucumber chlorophyll degradation.

Abstract:In order to analyze the variation of differentially expressed genes and the regulation mechanism of “drywet” adaptation in N. flagelliforme under hydration and dehydration. Highthroughput Illumina HiSeq PE150 sequencing platform and bioinformatics method were used to screen the droughttolerant differentially expressed genes of N. flagelliforme in this study. The results showed that: (1) a total of 3 383 differentially expressed genes were identified under hydration and dehydration, among which the significantly upregulated and downregulated genes were 1 767 and 1 616, respectively. (2) GO function enrichment analysis showed that the expression and regulation of differentially expressed genes mainly focused on protein synthesis and metabolism pathway in N. flagelliforme under dehydration. The KEGG significant enrichment analysis showed that the 46 differentially expressed genes in N. flagelliforme under hydration and dehydration were significantly enriched to the ribosomal metabolic pathway, all of which were upregulated. (3) Six genes that were significantly enriched in the ribosomal metabolic pathway were randomly selected for qRTPCR analysis, and the gene expression levels were consistent with the transcriptome sequencing results. These results suggested that N. flagelliforme might adapt to drought stress by inducing the gene expressions of ribosomal metabolic pathway in order to promoting droughtrelated protein synthesis and correct folding. These proteins involved in osmotic regulation and other important physiological activities in N. flagelliforme under dehydration.

Abstract:According to the description of Flora of China, the corolla of the normal Qinling stone butterfly is a twolipped structure (normal 23 type) with 2 upper lips and 3 lower lips, our group found a large number of artificially bred Qinling stone butterfly population Corolla variation type with twolobed upper lips and fourlobed lower lips (variants 24). In order to find out the reasons for the variation of Qinling stone butterfly petals, we used Illumina HiSeq 2500 highthroughput sequencing technology to sequence the transcriptome of the two different periods (buds and flowers) of the two flower types (normal 23 and variant 24) of Petrocosmea qinlingensis, and discover the differential genes involved in its flower development and explore the possible mechanism of floral variation. The results showed that: (1) compared with the NR database, a total of 52 677 Unigenes were annotated to the NR database, accounting for 46.25% of the total number of Unigenes, and the sequence homology with Dorcoceras hygrometricum was the highest (54.29%). (2) The results of GO enrichment analysis showed that the most significant GO terms for differential gene enrichment of normal 23 and variant 24 were the membrane classified by cellular component, the antiporter activity and enzyme inhibitor activity of molecular function class, transmembrane transport and negative regulation of catalytic activity of biological process, etc. The results of KEGG enrichment analysis showed that the most significant KEGG pathways for normal 23 and variant 24 differential gene enrichment were plant hormone signal transduction, fatty acid elongation, pentose and glucuronate interconversions, phenylpropanoid biosynthesis, sulfur metabolism, flavonoid biosynthesis, zeatin biosynthesis and other pathways. (3) The differentially expressed genes were screened and the 4 comparison groups were further analyzed by crosscomparison, and 6 genes that may be related to the development of P. qinlingensis flower organs were determined. They are PqMIF2, PqMYB340, PqMYB305, PqGATA12, PqCCD4 and PqZBED. qRTPCR verification found that its expression trend is consistent with the results of transcriptome sequencing analysis. This study provides valuable information for floral organ development, phylogeny and endangered mechanism of Petrocosmea qinlingensis.

Abstract:In order to find out the flower sex, mating system and flower bud differentiation process of Acer truncatum Bunge, we studied the flower bud differentiation process and flowering process of A. truncatum by paraffin section and continuous anatomical observation. The results showed that: (1) there were two kinds of flower sex: functional female flower and functional male flower. The anthers of functional female flower did not crack, and functional female flower only had female function. There were two types of functional male flowers: type Ⅰ and type Ⅱ. The anther of both two types of functional male flowers could produce mature pollen and crack. The functional male flowers only had male function. (2) A. truncatum was a rare tree species of duodichogamy, and there were two mating systems: protandrous and protogynous types. The order of floret opening of protandrous type is functional male flowers→functional female flowers→functional flower male flowers, and the order of floret opening of protogynous type is functional female flowers→functional male flowers→functional male flowers. (3) The morphological differentiation of flower bud began in early July, the differentiation of inflorescence and floret began in early August, the differentiation of stamen and pistil began in late August, and the development of female gametophyte was later than that of male gametophyte. (4) The key period of flower sex differentiation of A. truncatum is from late March to early April in the following year.

Abstract:Using American squash (Cucurbita pepo L.) powdery mildew resistant strain F2 and susceptible strain M3 as test materials, we inoculated the powdery mildew physiological race 2US spore suspension in an artificial climate box. The interaction between pumpkin seedling plants and powdery mildew fungus. The reactive oxygen species(ROS) metabolism of leaves and changes in protective enzyme activities after inoculation with powdery mildew were investigated, and the physiological mechanism of pumpkins against powdery mildew was explored. The results showed that: (1) compared with the susceptible strain M3, after inoculation with powdery mildew fungus, the pathogenic fungus on the leaves of the diseaseresistant strain F2 developed slowly and were more difficult to infect the leaves. (2) The H₂O₂ and O₂^-· contents of the diseaseresistant line F2 increased rapidly at the early stage of infection and then gradually decreased, while the H₂O₂ and O₂^-· contents of the susceptible line increased slowly at the initial stage of the disease, and maintained a high level after reaching the maximum, and the MDA content in leaves of susceptible strains was always higher than that of resistant strains. At the same time, through histochemical staining, we found that the leaf coloration of diseaseresistant strains was faster than that of susceptible strains, after which the staining area decreased and tended to a lower level. (3) The activities of antioxidant enzymes CAT, SOD, POD and PAL and PPO in the leaves of diseaseresistant strains F2 and susceptible strains M3 were significantly increased after inoculation with powdery mildew, but the activities and increase of diseaseresistant strains were higher than those of susceptible strains. Studies have found that the development of powdery mildew fungus on the leaves of diseaseresistant American squash for seeds is slow, and it is more difficult to be infected. After the mycelium is formed, the powdery spots on the leaves are smaller; Diseaseresistant strains rely on the increase of active oxygen to resist the invasion of pathogenic fungus at the initial stage of being infected by powdery mildew. As the content of active oxygen increases, diseaseresistant strains rapidly increase their own antioxidant enzyme activities to prevent oxidative stress; compared with susceptible strains, diseaseresistant strains can rapidly increase the activities of PAL and PPO after being infected by pathogenic fungus to resist infection by pathogenic fungus.

Abstract:With Leymus chinensis seedlings as the research object, we set 0, 10 and 20 times Fe²⁺ (Zn²⁺) concentration by adjusting the contents of iron and zinc in total nutrition medium (CK: 0.05 mmol/L Fe²⁺, 0.015 mmol/L Zn²⁺) as Fe₀ (Zn₀), Fe₁₀ (Zn₁₀), Fe₂₀ (Zn₂₀). And adding 0.15 mmol/L Zn²⁺ alone or 10 mmol/L Ca²⁺, 5 mmol/L Mg²⁺, 20 mmol/L K⁺ to the high concentration iron medium at the same time. We measured the growth index and mineral element contents of seedlings after 6 days of culture, as well as the antioxidant indexes and related gene expression in the roots of seedlings treated with high concentration iron (Fe₂₀), to explore the effects of different concentrations of Fe²⁺ and Zn²⁺ on the growth, mineral element absorption and accumulation, antioxidant indexes and gene expression in Leymus chinensis seedlings. The results show that: (1) deficiency of Zn (Zn₀) significantly inhibited the increase of fresh weight and the accumulation of Zn elements, but promoted the accumulation of Fe and Mg elements. High concentration of Zn (Zn¹⁰, Zn²⁰) significantly promoted the growth of seedling leaves and the accumulation of Zn. Deficiency of Fe(Fe₀) significantly inhibited the root length, fresh weight and the accumulation of Fe elements, and promoted the accumulation of Mg and Zn elements in seedlings. High concentration of Fe(Fe₁₀, Fe₂₀) significantly inhibited the root and leaf growth, root hair development and the accumulation of Ca, Zn, Mg and K elements in L. chinensis seedlings. (2) Increasing the concentration of Zn²⁺ and Ca²⁺, Mg²⁺, K⁺ could not restore the inhibitory effect of high concentration iron stress on seedling growth. (3) After treatment of L. chinensis seedlings with high concentration of iron (Fe₂₀) for 48 hours, the activities of peroxidase, superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase and the contents of malondialdehyde, ascorbic acid and reduced glutathione in roots increased significantly, while the gene expressions of nicotianamine synthase and peroxidase were downregulated significantly and plant germininlike protein were upregulated significantly. The research found that the growth and development of L. chinensis seedlings and the accumulation of mineral elements were not sensitive to the change of Zn²⁺ concentration in the environment, but were significantly inhibited by the high concentration of Fe²⁺ in the environment, and caused serious oxidative stress damage, which this damage cannot be recovered under the conditions of adding Zn²⁺ or adding Ca²⁺, Mg²⁺, K⁺ at the same time.

Abstract:The effects of parentals drought hardening on physiological characteristics and DNA methylation in maize were studied. Maize B73 and H99 selfbred offspring (G₁ generation) were used as materials which parents (G₀ generation) were trained by drought. The relative water content (RWC), the contents of malondialdehyde(MDA), soluble sugar, proline and the activities of superoxide dismutase (SOD) and peroxidase (POD) in leaves of G₁ and G₀ generations were measured by using 20% PEG6000 to simulate drought condition, and the methylation status of genome in G₀ and G₁ generations was detected by amplified fragment length polymorphism (MSAP) technique, and the variation of physiological indexes and genomic DNA methylation modification in two generations of maize were analyzed. The results showed that: (1) under the same drought treatment, the RWC, soluble sugar and proline contents, the SOD and POD activities of B73 and H99 in G₁ generation were higher than those in G₀ generation, the MDA content in G₁ generation was lower than that in G0 generation, the RWC reduction and MDA increase in G₁ generation were lower than those in G₀ generation, and the increase of soluble sugar and proline contents, SOD and POD activities in G₁ generation were higher than those in G₀ generation. (2) The DNA methylation levels and patterns in two generations of B73 and H99 were changed which caused by drought stress. Under the same drought stress, the changes of DNA methylation in G₁ generation were greater than that in G₀ generation. (3) The variations of DNA methylation in B73 and H99 were different. The methylation level of CG and CHG in B73 2 generations and the methylation level of CG in H99 2 generations were increased, and the methylation level of CHG were decreased. The variations of CG hypo and CHG hypo were dominant in B73 and CHG hypo and CG hyper were dominant in H99. The abilities of antioxidation, osmotic adjustment and the changes of DNA methylation in G₁ generation of B73 and H99 were higher than that in G₀ generation, and the drought resistance in G₁ generation was higher than that in G₀ generation. These results showed that there was transgenerational drought stress imprint in maize.

Abstract:With 2year old apple dwarf rootstock M9T337 as test material, using pot experiment method, we set watering water (CK) and saltalkali stress (0.1mol/L NaCl+NaHCO₃ solution), followed by spraying five concentrations of H₂O₂ treatment ［0 (T₁), 0.2 mmol/L (T₂), 0.4 mmol/L (T₃), 0.6 mmol/L (T₄), 0.8 mmol /L (T₅)］. The chlorophyll content, photosynthetic gas exchange parameters, osmotic adjustment substance contents, antioxidant enzyme activities and cell membrane permeability of each treatment were measured, and comprehensive evaluation was conducted by correlation and principal component analysis, so as to explore the physiological mechanism of exogenous hydrogen peroxide (H2O₂) enhancing salinealkali tolerance. The results show that: (1) the contents of chlorophyll a (Chl a), chlorophyll b (Chl b), total chlorophyll (Chl t), net photosynthetic rate (P_n), stomatal conductance (G_s), transpiration rate (T_r) and soluble protein (SP) content of M9T337 seedlings decreased gradually with the extension of salinealkali stress. Intercellular CO₂ concentration (C_i), soluble total sugar (TSS) content, proline (Pro) content, catalase (CAT) activity, ascorbate peroxidase (APX) activity, relative electrical conductivity (REC) and malondialdehyde (MDA) content all showed an increasing trend. The activities of superoxide dismutase (SOD) and peroxidase (POD) increased first and then decreased.(2) Compared with CK, each index of M9T337 seedling leaves changed in different amplitude after treatment with exogenous H2O₂, and there was an obvious concentration effect. The decreases of Chl a, Chl b, Chl t, SP and G_s in leaves treated with T₃ (0.4 mmol/L H₂O₂) were the smallest, and the increases of C_i, REC and MDA were the smallest. TSS, Pro and APX increased the most. (3) Leaf P_n of M9T337 seedlings was positively correlated with T_r, G_s, Chl a, Chl b, Chl t, SP, SOD and POD, and negatively correlated with C_i, MDA, CAT, APX and REC. (4) Comprehensive evaluation showed that the effect of each treatment on the physiological characteristics of M9T337 seedling leaves was in the order of CK>T₃>T₄>T₂>T₅>T₁. The results showed that the suitable concentration of H₂O₂ could effectively improve the photosynthetic capacity of M9T337 seedlings under saltalkali stress, significantly increase the activities of antioxidant enzymes and the contents of osmotic regulatory substances, and reduce the membrane permeability, so as to alleviate the saltalkali stress, and 0.4 mmol/L H₂O₂ treatment had the best effect.

Abstract:With the seeds of Lycium ruthenicum as the experimental material, the neutral salt NaCl, Na₂SO₄ and the alkaline salt NaHCO₃, Na₂CO₃ were simulated to form neutral compound salt L (1∶1∶0∶0), moderately basic compound salt M (1∶9∶9∶1) and severely basic compound salt H (9∶1∶1∶9) according to the proportion of alkaline salts from small to large, we used the Paper Germination experiment to study the effects of exogenous melatonine (0.1, 0.3, 0.5, 1.0 mmol/L) on seed germination and seedling growth of L. ruthenicum seeds under different saltalkali composition (L, M, H) and saltalkali concentration (50, 100, 200 mmol/L) combined stress. The results showed: (1) the growth phenotype of L. ruthenicum seedlings is obviously weakened with the increase of salinealkali concentration and alkaline salt proportion; Appropriate concentration of exogenous melatonine (0.1, 0.3, 0.5 mmol/L) could alleviate the damage of salinealkali stress on seedling growth to a certain extent, while excessive concentration of exogenous melatonine (1.0 mmol/L) will aggravate the damage. At the same time, the application of exogenous melatonine(MT) significantly increased the number of lateral roots of L. ruthenicum seedlings. (2) The germination process of L. ruthenicum seeds is closely related to salinealkali composition, salinealkali concentration and MT concentration. With the increase of the saltalkali concentration and the proportion of alkaline salt, the initial time of germination of L. ruthenicum seeds is delayed, and the total germination time is shortened; Applying an appropriate concentration of exogenous MT can advance the germination start time of L. ruthenicum seeds under salinealkali stress and prolong the total germination time. (3) In the L compound salt treatment, with the increase of the saltalkali stress concentration, the germination rate (GR), germination potential (GP), germination index (GI), vitality index (VI), shoot length (SL), root length (RL) all increase first and then decrease; In the M and H compound saltalkali treatments, all germination indexes showed a gradual decrease with the increase of the saltalkali stress concentration. (4) Exogenous MT has obvious “lowpromoting highsuppressing” phenomenon on the germination indexes of L. ruthenicum seeds, In the L compound salt, under the stress of 3 kinds of salt concentration, when the MT concentration is 0.1 and 0.3 mmol/L, it can promote GR, GP, GI, VI, SL and RL, and the comprehensive promotion effect of 0.1 mmol/L is the best, and when the MT concentration is 0.5 and 1.0 mmol/L, it has a inhibitory effect on GP, GR, GI and VI, when the MT concentration is 1.0 mmol/L, it has a inhibitory effect on SL and RL; Among the M and H compound saltalkali, under the stress of 3 kinds of saltalkali concentration, when the MT concentration is 0.1, 0.3, 0.5 mmol/L, it has a promoting effect on all indicators, and the comprehensive promotion effect of 0.3 mmol/L is the best, and when the MT concentration is 1.0 mmol/L, it has a inhibitory effect. Studies have shown that lowconcentration neutral compound salt treatment can promote seed germination and seedling growth of L. ruthenicum to a certain extent, while highconcentration neutral compound salt and moderate and severely alkaline compound salt have an inhibitory effect. Exogenous melatonin has a significant dose effect on the alleviation of seed germination and seedling growth of L. ruthenicum under saltalkali stress. When the melatonin concentration is 0.1 mmol/L, the comprehensive promotion effect on neutral complex salt stress is better, and melatonin at 0.3 mmol/L, it has the best promoting effect on moderate and severe alkaline complex salt stress.

Abstract:We used tomato cultivar ‘184’ as material, adopting the tomato protected substrate cultivation mode of water and fertilizer integration, taking the potassium fertilizer in plant nutrient solution formula C of Gansu Agricultural University as the control T₁ (conventional potassium fertilizer amount), and then adding different amounts of potassium fertilizer to formula C to treat T₂ (potassium fertilizer increment 25%), T₃ (potassium fertilizer increment 50%), T₄ (potassium fertilizer increment 75%), To explore the effects of different potassium application rates on the growth, physiology, yield and quality of tomato cultivated in protected substrate, and to screen the best potassium application rate under the condition of protected substrate cultivation. The results showed that: (1) compared with the conventional potassium fertilizer application (T₁), the increased application of potassium fertilizer (T₂-T₄) can significantly increase tomato plant height, stem thickness, and root vigor, and all the indicators of T₃ treatment are the highest, while the effect of increasing potassium fertilizer on the number of leaves was not significant. (2) Compared with T₁, the potassium fertilizer treatment can significantly increase the photosynthetic pigment content in tomato leaves, enhance the photosynthesis and fluorescence process, and further promote the absorption and transformation of light energy, and the T₃ treatment has the highest increase. (3) With the increase of potassium application rate, tomato single fruit weight and fruit yield of increased potassium fertilizer treatments showed different degrees of growth trends. Appropriate increase of potassium fertilizer treatments reached a significant level, and the T₃ tomato yield was the highest, and significantly increased 20.87% production by T₁. (4) Compared with T₁, the hardness, total soluble sugar, Vc, soluble protein, and lycopene contents of tomato fruits in each potassium application treatment increased to varying degrees, and each index increased first and then decreased with the increase of potassium application. The trend of change and reach the optimal under T₃ treatment. (5) Principal component analysis shows that the comprehensive score of each treatment is T₃>T₄>T₂>T₁. The study found that under the condition of facility substrate cultivation, adding a proper amount of potassium fertilizer can significantly improve the photosynthesis efficiency of tomato plants, promote plant growth, and achieve the purpose of increasing fruit yield and quality. The effect of treatment with a 50% increase in conventional potassium fertilizer was the best.

Abstract:In order to reduce the use of nonrenewable resources of peat and the production cost of soilless culture substrates, with the melon variety “Yangjiaomi” as the test material, we mixed the rice husk ash and the commercial finished cultivation substrate according to different volumes［1∶5(T₁), 2∶4(T₂), 3∶3(T₃), 4∶2(T₄) and 5∶1(T₅)］, and with the commercial finished cultivation substrate without added husked ash as CK, to study the physical and chemical properties of different substrates and their effects on melon growth, leaf chlorophyll content, photosynthetic gas exchange parameters and fruit quality. The result shows: (1) adding a certain amount of rice husk ash to the commercial finished cultivation substrate can significantly improve the aeration of the substrate, increase the pH and EC (electrical conductivity) of the mixed substrate and observably inhibited the number of microorganisms in the substrate. (2) Compared with CK, the right amount of rice husk ash mixed matrix can significantly promote the growth of melon plants. Among them, under T₂ treatment, the plant height of the melon plant, root vitality and root shoot ratio significantly increased by 14.69%, 19.73%, and 23.08%, respectively. (3) Under T₂ treatment, the chlorophyll content, net photosynthetic rate, stomatal conductance and transpiration rate of melon leaves increased significantly. (4) The transverse diameter, longitudinal diameter, single fruit weight and yield per plant significantly increased compared with the control, the weight of single fruit of melon increased by 20.3%, and the contents of fruit soluble sugar, soluble solids, soluble protein, sucrose, glucose, etc. increased significantly, sucrose synthase and sucrose phosphate synthase activities had been significantly improved. The study found that mixing proper amount of rice husk ash can effectively improve the physical and chemical properties of cultivation matrix, observably increase the photosynthesis ability of melon leaves, and improve the quality of melon fruit. The mixture matrix formula with a volume ratio of 2∶4 between rice husk ash and commercial finished cultivation substrate was the most suitable one, can replace the traditional substrate for melon cultivation.

Abstract:In this study, Bupleurum chinense was used as material, and the PEG6000 nutrient solution with a mass fraction of 10% and 20% was used to simulate drought stress experiments. The contents of endogenous signal substances OPR and JA, the expression of transcription factor BcMYC2 and the key enzyme genes in the saikosaponin biosynthesis pathway, and the contents of saikosaponin a and d were detected for exploring the mechanism of jasmonic acid signaling pathway regulating BcMYC2 and affecting saikosaponin biosynthesis under simulated drought stress. The results showed that: (1) after PEG6000 was used to simulate drought stress to treat the seedlings of Bupleurum chinense, the OPR content in the 20% PEG6000 treatment group showed a peak at 2 h, and the OPR content of the 10% PEG6000 treatment group peaked at 6 h. However, the endogenous JA peaked at 2 h for both treatments. (2) In both treatment groups, the relative expression of BcMYC2 show a peak at 2 h and then decreased significantly in 2-4 h, and the relative expression of BcMYC2 in 20% PEG6000 group was higher than that in 10% PEG6000 group. The relative expression of HMGR, IPPI, FPS and βAS of the other four key enzymes of saikosaponin biosynthesis pathway reached the peak at 4 h. The peak time of relative expression of BcMYC2 was earlier than the relative expression of these key enzyme genes. (3) Saikosaponin content in seedling roots gradually increased within 36 days after simulated drought stress. At 36 days, the content of saikosaponin in the 20% PEG6000 treatment group was slightly higher than that in the 10% PEG6000 treatment group. Studies have shown that after PEG6000 simulated drought treatment, the contents of signal substances OPR and JA in Bupleurum chinense DC. seedlings increased, which promoted the expression of BcMYC2, thereby increasing the expression of key enzyme genes in the saikosaponin biosynthetic pathway and ultimately affected the content of saikosaponin in roots.

Abstract:A pot experiment with natural water consumption after artificial watering was conducted to study the effects of drought stress on water, photosynthesis, chlorophyll fluorescence in leaves of three desert species, Haloxylon ammodendron, Nitraria tangutorum and Artemisia desertorum. The change characteristics and response mechanism of each index in the process of drought stress and its quantitative relationship with soil water were discussed, and their drought resistance was ranked by membership function method. The results showed that: (1) the relative water content (RWC) of three species leaves decreased continuously with the extension of drought stress time, and the water deficit (RWD) showed a fluctuating upward trend. (2) The contents of Chl, Chla, Chlb of the three species and carotenoids in H. ammodendron and N. tangutorum was decreased with the increase of stress days. The carotenoids of Artemisia desertorum increased with the decrease of soil moisture. (3) The P_n, T_r, WUE and other main gas exchange parameters of the three species showed significant threshold response to soil water content. The suitable soil water content thresholds for normal photosynthetic physiological activities were 8.04%-19.33%, 4.17%-19.10% and 6.48%-17.51%, respectively. (4) The F_v/F_m, F_v′/F_m′ and qP of the three species decreased with the increase of drought stress days and light intensity, and NPQ showed a gradual upward trend. F_v/F_m and F_v′/F_m′ of H. ammodendron, A. desertorum decreased, photosynthetic activity was destroyed, and electron transfer was blocked. PSⅡ reaction center was damaged and showed photoinhibition after 30 days and 18-30 days of stress. However, N. tangutorum has stronger ability to regulate its PSⅡ reaction center to avoid injury. (5) The comprehensive analysis of membership function method showed that the drought tolerance of three species was N. tangutorum, H. ammodendron and A. desertorum. The results showed that all the three desert species showed strong tolerance to drought stress by adjusting the opening degree and activity of PSⅡ reaction center. At the late stage of stress, the plants PSⅡ reaction center closed or irreversibly inactivated and showed photoinhibition.

Abstract:We determined and analyzed the phenotypic characteristics and nutritional components of Paeonia suffruticosa Andr ‘Fengdan’seeds from 12 introduced areas in Sichuan basin, and combined with ecological factors such as meteorology, soil nutrients and altitude, in order to provide theoretical support for scientific introduction and highefficiency cultivation of ‘Fengdan’. The correlation between seed characters and ecological factors was studied and key ecological factors affecting seed quality were revealed. The results showed that: (1) the transverse diameter, longitudinal diameter, seed shape index and 1 000 grain weight of phenotypic characters of ‘Fengdan’ seeds in each sampling area had extremely significant differences (P < 0.01), and their variation ranges were 7.98-10.63 mm, 7.75-10.86 mm, 0.80-1.32 and 311.23-393.15 g, respectively. The longitudinal diameter and 1 000 grain weight of seeds in Nanjiang County of Bazhong City were the largest (10.86 mm, 393.15 g), and the transverse diameter and seed shape index were the largest in Ebian County of Leshan City and Xichong County of Nanchong City (10.63 mm, 1.32). (2) There were significant differences in oil, protein, αlinolenic acid and linoleic acid contents (P<0.01) in the seeds of ‘Fengdan’ from different sampling sites, and the ranges of their changes were 20.5%-26.9%, 15.6%-19.6%, 42.8%-47.1% and 15.7%-19.6%, respectively, which were higher in Nanjiang County of Bazhong City (26%, 18.3%, 47.1% and 18.3%). (3) The 1000grain weight of ‘Fengdan’seeds was significantly correlated with the content of αlinolenic acid and linoleic acid (r = 0.760 and -0.701), and the contents of linoleic acid and oleic acid were significantly correlated with the contents of protein (r =-0.686 and 0.665), while αlinolenic acid was negatively correlated with linoleic acid (r =-0.904), and palmitic acid was negatively correlated with stearic acid (r =-0.792). (4) The contribution of site conditions to the phenotypic characters and nutrient components of ‘Fengdan’seeds were as follows: available potassium > organic matter > altitude > available nitrogen > available phosphorus > pH, the contribution rates of climatic conditions are annual sunshine > average temperature of January > average temperature of July > annual rainfall > annual average temperature, among which altitude has a greater effect on seed phenotypic characters, and available potassium has a greater effect on seed shape index and oleic acid. The effects of organic matter and alkalihydrolyzable nitrogen on protein and oil contents were significant, and there were positive correlations between altitude, available potassium, available phosphorus, alkalihydrolyzable nitrogen and temperature with seed phenotypic traits, oil, αlinolenic acid, protein and palmitic acid contents, negative correlation with stearic acid and linoleic acid contents. The study found that there were significant differences in the phenotypic characters and the contents of main nutrient components of ‘Fengdan’ seeds introduced from different regions in Sichuan basin, ecological factors such as weather, soil nutrients and altitude have important effects on seed quality of ‘Fengdan’. We suggest to plant ‘Fengdan’ at areas with higher altitude and higher temperature, and rich in soil nutrients (organic matter, available potassium, available phosphorus, and alkalinehydrolyzed nitrogen).

Abstract:This is the first report to Trichodon cylindricus var. oblongus in China, and the genus Trichodon to the Xinjiang Uygur Autonomous Region. The study showed that: (1) the variety is characterized by the leaves widespreading when moist, with a broad and sheathing base, rather abruptly narrowed to a long, linear subula, plane margins, costa filling most of the subula, rough at back, a stereid band on abaxial of guide cells, leaf cells rectangular to shortrectangular; tubers on rhizoids; ellipsoidal capsule slightly curved, with linearlanceolate segments divided into two nearly to base. (2) There are three taxa of Trichodon in China up to now. T. cylindricus var. oblongus can be easily separated to var. cylindricus by shorter seta and capsule. T. cylindricus var. oblongus is characterized by the tuber present, leaf with sheathing base, plane margins, while T. muricatus Herzog is characterized by tuber absent, leaf with slightly sheathing base, recurved margins. (3) In Ditrichaceae, many genera have stereid band on both adaxial and abaxial sides of guide cells. Just genus Trichodon has stereid band differentiate only on abaxial side. T. cylindricus var. oblongus has squarrose leaves versus other genera of Ditrichaceae have erect leaves or nearly so. It has leaf with sheathing base, smooth capsule when dry, and incurved segments of peristome versus the genus Ditrichum has leaf without sheathing base, strongly furrowed capsule when dry, and straight segments of peristome. (4) Trichodon cylindricus var. oblongus is a dispersed type to arcticalpine. It is a disjunctly distributed species on EuropeAsiaNorth America continent. The taxon may be viewed as an indicator in research for climate change and the transformation between sea and continent.

Abstract:The Gyirong Gorge is the largest water vapor passage in the western Himalayas, with good hydrothermal conditions and a diverse topography, which has given rise to impressive plant diversity. This paper reports on two new recorded species of the genus Meconopsis in China, M. autumnalis P. Egan and M. bella Prain, and a species recorded again after publication, M. polygonoides (Prain) Prain, found in Gyirong County, Tibet. The morphological descriptions and notes on their distribution and habitat are provided, and the differences with closely related species are also explained briefly. The discovery has enriched the flora of Tibet and provided new information for the study of the genus Meconopsis in China. Taking into account the historical surveys, the authors of this paper believe that the plant diversity survey in Gyirong County should be adjusted to reduce the overcollection of the traditional Gyirong gorge, i.e. the Gyirong County, along the Gyirong Tsangpo to Gyirong Town, and should be collected in depth towards the Gyirong port and on both sides of the Gyirong gorge.

Abstract:The current paper carried out a study on the morphological characters of Distrionella incognita (Reichardt) D.M. Williams collected from a river in Menyuan County of Qinghai Province, using light and scanning electron microscope. In order to determine its taxonomic genus and species, the characteristics of the species are compared with its similar species, D. asterionelloides D.M. Williams. The results demonstrate that, (1) the specimens of D. incognita collected from Menyuan County of Qinghai Province have eight diagnostic characters: ① narrowlanceolate valve outline and capitate apices; ② three types of transapical ribs: primary rib, secondary rib, and tertiary rib; ③ stellate colony; ④ unevenly distributed uniseriate striae on the valve surface; ⑤ not raised sternum; ⑥ each valve bearing only one rimoportula at one apex; ⑦ nonocellulimbustype apical pore field; ⑧ only one row of poroids along the midline of the valvocopula. Therefore, it is confirmed as determined that the diatom is D. incognita in this paper. (2) To characterize D. incognita, a comparison was made with its similar taxa, D. asterionelloides. The main difference between the two species is that the former can form a zigzag or stellate colony, while the latter is solitary and does not form a colony. Thus, the two species are different. (3) The results of this study expanded the geographical distribution area of D. incognita, confirmed that D. incognita is a new record species in China. The permanent slides are deposited in the Herbarium of Jishou University (JIU).

Abstract:ReceptorLike Kinase (RLK) genes are one of the most important gene families in the angiosperm genome. A typical RLK protein consists of an Nterminal extracellular domain, a transmembrane region and a Cterminal intracellular kinase domain. Because of the specific evolutional characteristics of each plant, each subfamily and the number of RLKs were largely changed among different plants. Gene duplication, both fragmental and tandem, is the main cause of the rapid variation. We summarized the current progress in the study of RLKs in Rosaceae fruit trees, including genomewide identification, the evolutionary characteristics, the roles of RLKs on cell growth and development and responses to biotic and abiotic stresses in Rosaceae fruit trees. The studies on the roles of RLKs in the development of Rosaceae fruit trees have focused on roots, fruits, and pollen tubes. Plant RLK genes have a great significance to the growth and development, environmental adaptation and disease resistance of fruit trees. However, the research results of plant RLKs in Rosaceae fruit trees are not deep enough compared with model plants. We suggested that the future investigations in this field could focus on specific traits of Rosaceae fruit trees, such as developmental stage transition, dormancy, selfincompatibility, fruit development and quality formation, interactions between rootstock and scion and specific diseases (Valsa canker, apple ring rot, etc.). Based on molecular breeding, the target RLKs will be screened and induced for rapid application in practical production.