Isopentenyl pyrophosphate isomerase（IPP） is responsible for the reversible isomerization of isopentenyl pyrophosphate and dimethylallylpyrophosphate（DMAPP）， playing an important role in the biosynthesis of downstream terpenoid products. In this paper， 31 IPP genes were identified from genomes of various mono- and dicotyledonous plants such as Oryza sativa and Arabidopsis thaliana by bioinformatics method. Phylogenetic analysis indicated that these IPPs were divided into three clades， in which those from monocotyledon plants formed a monophyletic clade. IPPs within the same clade shared similar domains and might have similar biological functions. The analysis on cis-regulatory elements of O. sativa and A. thaliana IPP genes exhibited multiple response elements such as drought response elements. Finally， quantitative PCR results showed that the expression patterns of IPP transcription levels in O. sativa and A. thaliana were diversified. These above results provided theoretical basis for systematic understanding and further application of IPPs.
In order to explore the genetic background of tulip germplasm resources， accurately evaluate and screen excellent germplasm for genetic improvement of tulips， the genetic background of 40 tulip varieties was analyzed by SRAP molecular markers， and their genetic diversity and relationships were clarified， respectively. The results showed that out of 43 pairs of SRAP primers， 21 pairs of polymorphic primers were available for genetic diversity analysis of tulips， and 249 clear and stable bands were amplified in the 40 tulip varieties， of which 245 were polymorphic bands with a polymorphism rate of 98.39%. The genetic similarity index of the 40 tested varieties ranged from 0.502 0 to 0.867 5， and the genetic diversity parameters including the number of alleles（Na*）， number of effective alleles（Ne*）， Nei’s gene diversity index（H*）， Shannon’s information index（I*）， and polymorphic information content were 1.981 0， 1.514 9， 0.304 2， 0.460 3， and 0.321 2， resp-ectively， indicating rich genetic diversity in the tested materials. Cluster analysis and principal coordinate analysis showed that the 40 tulip varieties were classified into two major groups， among which ‘Christmas Magical’， ‘Banja Luka’， and ‘Madame Lefeber’ were relatively distant genetic relationships from other varieties and had certain differences in their genetic backgrounds.
In order to explore the metabolic mechanism of Lanzhou lily（Lilium davidii var. unicolor） in response to autotoxicity stress， one-year-old（Lily1）， two-year-old（Lily2） and three-year-old（Lily3） Lanzhou lilies were used as materials， and gas chromatography-mass spectrometry（GC-MS） was used to analyze the metabolomic changes of Lanzhou lily under continuous cropping years， and a total of 124 metabolites were detected and identified. R software was used to normalize the samples， and orthogonal partial least squares discriminant analysis（OPLS-DA） was used to find differential metabolites， and related metabolite pathways were screened for joint analysis. The results showed that there were 16 differential metabolites（lipids， flavonoids， saccharides and phenols） between Lily1 and Lily2， and all of them were up-regulated； and it was significantly enriched in tyrosine metabolism， propionic acid metabolism and flavonoid biosynthetic metabolic pathways. The contents of lipids， flavonoids and saccharides increased， indicating that in the second year of continuous cropping， Lanzhou lily responded to autotoxicity stress by actively synthesizing lipids， flavonoids and saccharides. There were 21 differential metabolites between the metabolomes of Lily1 and Lily3， including one up-regulated metabolite（3-α-mannobiose） and 20 down-regulated metabolite packages （amines， acids， and lipids）； and five metabolic pathways were significantly enriched， including biosynthesis of tropane， piperidine and pyridine alkaloids， phosphate and hypophosphite metabolism， lysine degradation， glutathione metabolism and D-amino acid metabolism. There were 21 differential metabolites between Lily2 and Lily3 groups， and the only up-regulated metabolite was 3-α-mannobiose. The results showed that in the third year of continuous cropping of Lanzhou lily， saccharides， as carbohydrates， were directly involved in cell membrane stability， actively responded to autotoxicity stress. The 20 down-regulated metabolites were amines， acids and lipids； only the propionic acid metabolism and flavonoid biosynthetic metabolism pathways were significantly enriched.
Ribulose-1，5-diphosphate carboxylase/oxygenase（Rubisco） is a key enzyme in photosynthesis， in which small subunits（rbcS） are encoded by nuclear genes and mainly expressed in leaves. In this study， the Rubisco small subunit genes PxrbcS1 and PxrbcS2， which are highly expressed in Populus × xiaohei’s leaves， were determined by RT-qPCR technology， and their upstream promoters of 2 240 and 2 174 bp were cloned respectively. The results of promoter element analysis showed that the promoters of PxrbcS1 and PxrbcS2 had multiple elements related to light induced expression， including G-box， MRE and Box4 elements. Plant expression vectors of pBI-121-pPxrbcS1：：GUS and pBI-121-pPxrbcS2：：GUS were constructed and genetically transformed into 84K poplar（P. alba×P. glandulosa）. GUS histochemical staining and qPCR expression analysis showed that the promoters of PxrbcS1 and PxrbcS2 could drive the GUS gene to express in 84K poplar leaves with high specificity. In conclusion， the above results showed that PxrbcS1 and PxrbcS2 promoters with high leaf expression activity were successfully cloned from P.×xiaohei， and the promoters might be applied to the study of gene functions related to plant photosynthesis and genetic operations to improve photosynthesis in plants， including poplars.
Psathyrostachys juncea was considered an important ancestral species of Leymus. The genomic Cot-1 DNA library with highly repeat sequences of Psa. juncea was constructed， and sequenced and characterized， and the results showed that the library could be classified into six types： retrotransposons， transposons， satellite DNA， LZ-NBS-LRR， uncharacterized sequences， and retrotransposon LTR mixed LTR/Copia， and the proportions were 49.5%， 1.0%， 28.7%， 5.9%， 13.9% and 1.0% of the Cot-1 DNA， respectively. Furthermore， two satellite DNAs and five retrotransposon sequences were used as probes， and chromosomes in Psa. juncea， Leymus secalinus and L. racemosus were detected by florescence in situ hybridization （FISH）. The results showed that the hybridization signals of satellite DNA sequences TaiI-family and pSc250-family were mainly distributed at the ends of chromosomes， and the number of TaiI-family hybridization signals were 20， 16， 7， and 18 in Psa. juncea， L. secalinus， L. racemosus （PI 531811） and L. racemosus （PI 531812）， respectively， and the number of pSc250-family hybridization signals were 17 and 24 in Psa. juncea and L. secalinus， respectively， but no signal was detected in two L. racemosus samples. The distribution of retrotransposon sequences on the chromosomes of three detected species was basically dispersed， and the distribution of chromosome sequences in Leymus species showed a tendency of homogenity. Especially， clone sequences pPj-44 and pPj-28 showed significant differences in signal distribution between Psa. juncea and Leymus species， suggesting sequence expansion and contraction， respectively， during allopolyploidization， and clone sequence pPj-77 only differentiated the hybridization intensity of 10 chromosomes from the rest of the chromosomes in one L. racemosus（PI 531812）. The results suggested the repeats of Psa. juncea evolved rapidly and had homogenous diffusion during the polypoid formation of Leymus species and the repeat composition might be significant different among different Leymus species.
In order to explore the ploidy level and genome size of Sorbus sect. Sorbus species， the nuclear DNA content from somatic cells was measured by flow cytometry and Oryza sativa subsp. japonica ‘Nipponbare’ was used as the internal control. The results showed that the genome size of 19 species ranged from 0.648 to 0.803 pg， with the diploid， triploid and tetraploid levels， including 15 diploid species with 2C values ranging from 1.335 to 1.607 pg for， and one triploid species S. himalaica with 2C values of 2.137 pg，and three tetraploid species， S. albopilosa， S. prattii and S. pseudovilmorinii， with 2C values of 2.594， 2.891 and 2.751 pg， respectively. The 2C values of 16 species and new ploidy levels of five species were reported for the first time， indicating that there were changes of ploidy heterogeneity among interspecific and intraspecific in Sorbus sect. Sorbus.
The expression of gene transcription activation based on CRISPR-dCas9 might avoid phenotypic interference caused by gene ectopic expression， and made genes expressed efficiently and specifically. In this study， a novel CRISPR-Act3.0 expression system based on CRISPR-dCas9 was used to perform transcriptional activation of the vascular cambium-specific transcription factor ANT（AINTEGUMENTA） in Populus trichocarpa to create genetic materials and function analysis. First， homology analysis was conducted on the PtrANTs transcription factors of P. trichocarpa， and PtrANT-4 was selected for subsequent research. PtrANT-4 gene was cloned and its expression in various tissues was analyzed using fluorescence quantitative PCR. Secondly， three gRNAs were designed on the gene promoter of PtrANT-4， and the transcriptional activation expression vector CRISPR-dCas9/ANTprogRNAs was constructed. The expression of the vector was detected by transient protoplast transformation method. Finally， the expression vector was transformed into P. trichocarpa using Agrobacterium-mediated method， and transcription-activated genetic plants of PtrANT-4 were obtained. The results showed that there were four PtrANTs transcription factors in P. trichocarpa. PtrANT-4 was specifically expressed in vascular cambium of lateral meristem of P. trichocarpa. The transcription activation vector successfully constructed based on the CRISPR-Act3.0 expression system has the transcriptional activation effect of PtrANT-4 after transformation in xylem protoplasts of P. trichocarpa. The expression level of the PtrANT-4 gene in the genetically transformed plants was significantly increased only in the vascular cambium， suggesting that PtrANT-4 might play an important role in the development of stem vascular cambium This study lays a foundation for the functional study of PtrANT， and provides important genetic materials for the study of the mechanism of vascular cambial stem cell development.
To explore the metabolic response mechanism of Lagerstroemia indica ‘Pink Velour’ to salt and alkali stresses， one-year-old asexual cottage seedlings were treated to salt stress（NaCl， pH=7.02） and alkali stress（NaHCO3 and Na2CO3， Na+ mole ratio 2∶1， pH=9.52） respectively， and the leaves metabolic changes and differences of the two treatment groups and the control group（CK） were analyzed and compared by using liquid chromatography mass spectrometry（LC-MS）. The results showed that 156 and 176 different metabolites were screened in salt and alkali stress group respectively， and 23 different metabolites were screened in both groups， and the rest were unique different metabolites. KEGG enrichment analysis showed that the biosynthesis of secondary metabolites， amino acid metabolism， carbohydrate metabolism， fatty acid metabolism and plant hormone synthesis were main metabolic pathways in response to salt and alkali stress. Glycine， serine and threonine anabolism， ABC transporter protein and Vitamin B6 anabolism were the unique metabolic pathways in salt stress groups. Biosynthesis of valine， leucine， isoleucine， arginine， proline， folic acid and ascorbic acid， and mutual transformation between pentose and glucuronic were the unique metabolic pathway in alkali stress groups. The changes of different metabolites and enriched metabolic pathways might be the main mechanism of L. indica response to the salt stress and alkali stress.
FERONIA （FER） receptor kinase plays an important role in pollen and stigma recognition in flowering plants. To analyze the function of receptor-like kinase FERONIA（FER） in the pollination in ornamental kale（Brassica oleracea var. acephala）， BoFER gene was cloned from the stigma of the self-incompatibility line（S13-bS13-b ） of ornamental kale by RT-PCR， and the cloned cDNA sequence was 2 682 bp， which encoded 893 amino acids containing the highly conserved kinase domain and Ser/Thr kinase binding site， and the expression level of BoFER was analyzed by qRT-PCR. The results showed that the expression of BoFER in stigmas gradually increased after incompatible pollination， but gradually decreased after compatible pollination. Furthermore， the interaction between BoFER and known proteins related to self-incompatibility were analyzed by yeast two-hybrid. The results suggested that BoFER interacted with the kinase domain of S-locus receptor kinase BoSRK13-b.
To analyze gene function in plants lacking stable genetic transformation system， virus-induced gene silencing（VIGS） was needed， and Iris sanguinea， a monocotyledon， was selected as materials. The specific fragment of IsPDS gene was isolated and the VIGS recombinant vector pTRV2-IsPDS was constructed and leaves were infected by injection. The results showed that the most effective infection was achieved by injecting its leaf veins with syringes when the OD600 values of the resuspension were adjusted to 0.8-1.0 after the those of pTRV1 and pTRV2-IsPDS were adjusted to 1.8-2.0. The experiment was conducted when outdoors temperature was 15-20 ℃ from 6 p.m. to 8 p.m.， and a 1 mL syringe needle pricking the outer epidermis of I. sanguinea leaves and 1 mL of heavy suspension slowly injected along parallel veins into its vascular bundles. A clear albino phenotype might appear after about 14 days. TRV1 and TRV2 virus vectors were detected in the plants with phenotypic changes and in the no-load group. The expression of IsPDS in the albino plants was significantly lower than that in the no-load group and the control group. With the concentration of agrobacterium tumefaciens carrying virus vector increased in the preparation of infection solution， the infection efficiency of the whole experiment was improved， and no shading was needed after inoculation.
To provide theoretical basis for genetic improvement of reproductive regulatory traits of Catalpa bungei， DELLAs family genes were identified and the function of CbuGRAS9 was analyzed. Based on the genomic data of Catalpa bungei， five CbuDELLAs genes homologous to Arabidopsis thaliana were identified and cloned. ExPASy， SWISS-MODEL， Plant-mPloc， PlantCare and other online tools were used to predict the isoelectric point， protein structure， sub-cellular localization and promoter cis-acting elements of CbuDELLAs protein. The expression differences of CbuDELLAs were analyzed by using Catalpa ‘Bairihua’ and Catalpa bungei ‘Luoqiu No.1’ as materials， and the molecular function of CbuGRAS9 was confirmed by heterologus transformation in Arabidopsis thaliana， and the proteins interacted with CbuGRAS9 were screened by yeast two-hybrid library. The results showed that the amino acid number of the five CbuDELLAs proteins ranged from 455 to 588 aa， the relative molecular weight of the proteins ranged from 5.04 to 6.43 kDa， and the isoelectric point value ranged from 4.81 to 5.14. All CbuDELLAs proteins contained DELLA and GRAS conserved domains and are hydrophilic proteins. Sub-cellular localization prediction showed that CbuDELLAs protein was located in the nucleus. The analysis of promoter cis-acting elements showed that the five promoter regions of DELLAs all contained cis-acting elements involved in gibberellin reaction. The results of qRT-PCR showed that the expression of CbuDELLAs in Catalpa ‘Bairihua’ were significantly higher than that in Catalpa bungei ‘Luoqiu No.1’， and CbuGRAS9 was the most significantly gene， and the flowering time of CbuGRAS9 transgenic plants were significantly delayed. Proteins interacted with CbuGRAS9 were mainly concentrated in metabolic pathways such as ribosome， amino acid synthesis， secondary metabolism， photosynthesis and TCA cycle.
