Stems of Populus simonii×P. nigra ‘Baicheng’ in vitro plants were selected as explants and MS medium was used to establish tissue culture system by adjusting the hormone concentrations of 6-BA， NAA， TDZ and IBA. Based on the tissue culture system， the optimal concentration of kanamycin and infection time were confirmed to establish Agrobacterium tumefaciens-mediated genetic transformation system for P. simonii×P. nigra ‘Baicheng’. By using this system， the transgenic plants overexpressed a key tension wood formation regulator LBD39 （Lateral Organ Boundaries Domain） were created successfully. The results showed that the tissue culture system consisted of three stages， including adventitious bud differentiation induction （MS+ 0.5 mg·L-1 6-BA+0.1 mg·L-1 NAA+0.001 mg·L-1 TDZ， shoot differentiation rate=92.6%）， stem induction （MS+0.2 mg·L-1 6-BA+0.05 mg·L-1 NAA， multiplication coefficient=6.5） and rooting induction （1/2 MS+0.4 mg·L-1 IBA， rooting percentage=100%）. The optimal kanamycin concentration for genetic transformation was 30 mg·L-1 and the optimal infection time was 20 min， and the transgenic plants were obtained successfully after 30 d of adventitious bud differentiation induction， 15-30 d of stem induction and 25 d of rooting induction with 2% transformation efficiency respectively. By using this system， five overexpressed plants of LBD39 were obtained， and the transformation efficiency was 3.3%.
To screen out the tomato（Solanum） germplasm with waterlogging tolerance， 50 tomato germplasm were selected as the research object， and the survival rate and physiological indexes were compared after semi-submerged and submerged treatments respectively. The results showed that 12 waterlogging tolerant tomato germplasm with 100% survival rate after seven days submergence treatment were selected， and 12 waterlogging-tolerant germplasm were observed and distributed in S. lycopersicum，S. lycopersicum var. cerasiforme and S. pimpinellifolium respectively. Further analysis on waterlogging-tolerant tomato TK017 and waterlogging-sensitive tomato TK039 revealed that tomato TK017 could control the content of reactive oxygen species more effectively under submergence condition， and improved the waterlogging tolerance of tomato.
In order to investigate the molecular mechanisms of protein responses in Triadica sebifera to salt stress， two T. sebifera lines， including salt-sensitive P18（SS18） and salt-tolerant P21（ST21） were selected and treated with 0.4% NaCl solution. Isotope tags for relative and absolute quantitation（iTRAQ） were used to quantify leaf proteins abundance changes at different stress periods（0， 24， 72 h）. A total of 279 and 106 differentially expressed proteins（DEPs） were detected in SS18 and ST21， respectively. Four proteins， including catalase， extension factor 1-α， H+-ATPase c domain protein and thioredoxin， were significantly up-regulated in two clones under salt stress， suggesting that they may be important potential target proteins in the salt-tolerant response of T. sebifera’s. Pathway enrichment analysis showed that the DEPs of T. sebifera leaves under salt stress were primarily associated with photosynthesis， carbohydrate metabolism， amino acid metabolism， and fatty acid metabolism. The protein-protein interaction network showed that 5 core proteins（24 h） and 3 core proteins （72 h） involved in glucose decomposition and energy metabolism in SS18， while ST21 had 5 （24 h） and 4 （72 h） core proteins involved in carbon metabolism， photosynthesis， carbon fixation， photosynthesis and related to chlorophyll a-b binding. ST21 leaves improved metabolic pathways of sugars， amino acids and fatty acids， and accumulated a large number of small molecular soluble substances such as soluble sugars， amino acids and organic acids under salt stress， which might be an important aspect of salt stress response.
To explore the fruiting characteristics and seed characteristics and their variation patterns of Abies species distributed in Northwest Yunnan， and to provide material support and theoretical basis for promoting the regeneration and restoration of Abies forest， the specimens and cones of seven Abies species distributed in Northwest Yunnan were collected and identified， and the seed morphological characteristics， seed viability， and fruiting characteristics were analyzed， and then the differences among species and regions were explored separately. The results showed that the length， width and thickness of seeds of seven Abies species in Northwest Yunnan were 6.04-10.22 mm， 2.03-3.32 mm and 1.26-2.24 mm， respectively， and the thousand-grain weight was 4.26-30.50 g. The thousand-grain weight was significantly correlated with seed length， width and thickness （r>0.8， P<0.01）. The average rates of plump， empty and insect-eaten seeds of seven Abies species in Northwest Yunnan were 27.51%， 4.92% and 67.58%， respectively. The rate of plump seed was low， and that of empty and insect-eaten seeds was high. Abies ernestii var. salouenensis was not further analyzed in this article due to field investigations revealing that most of them had no cone and only one tree’s cones were collected in this study. For the other six species， the rate of insect-eaten seeds did not differ significantly between species（P=0.750）， or between regions（P=0.204）. However， there were interspecies differences in the rate of plump seeds（P=0.005） and empty seeds（P=0.007）. There were interspecific（P=0.008） and interregional（P=0.036） differences in Abies seed viability. Therefore， seed viability of Abies was affected by both species characteristics and environmental factors.
To provide the theoretical basis for genetic improvement of Betula platyphylla， the genetic variation of the growth and wood characters of B. platyphylla half-sibling families were studied， and the excellent pulp families were selected， and 32 seven-year-old half-sibling families were measured respectively， and the growth and wood characters of each family were analyzed by ANOVA， genetic parameters were calculated and general combining ability was estimated， multiple selection methods were used to select excellent families and evaluate excellent parents. The results showed that there were significant differences （P<0.01） in growth and wood characters among families， and the family heritability was 0.71-1.00， the heritability per plant was 2.0-3.0， the coefficient of variation ranged from 5.88% to 49.84%. There was a significantly and strongly positive correlation among DBH， tree height and volume（r：0.70-0.97）， and fiber length to width ratio had a significantly and strongly positive correlation with the fiber length（r：0.69）， while it had a significantly and strongly negative correlation with the fiber width（r：-0.76）. The general combining ability was used to evaluate the excellent parents， and the general combining ability ranges of volume， basic density and fiber length were -0.001 1-0.001 0， -0.04-0.07 and -112.09-77.36， respectively. The maternal parents of A13， A12， A21 and A24 were selected as excellent parents， and three different selection methods， including Brekin multi-trait comprehensive analysis method， principal component analysis method and breeding value method， were used to select the excellent family. After comparing the advantages and disadvantages of the three methods， five excellent pulp families were selected， and the average genetic gain of volume and cellulose reached 12.97% and 3.40%， respectively. A12， A17， A23， A19， A1 were selected as the excellent pulpwood families， which provided material for further breeding of improved varieties of fast- growing B. platyphylla.
Abnormal chloroplast division homozygous mutant strain parc6 and albinistic cotyledon homozygous mutant strain sco2 were identified at the DNA， RNA and cellular levels， while the effects of chloroplast abnormal division on the growth of cotyledon and leaf were investigated by adding different concentrations of sucrose to the medium and taking sl2， the double mutant with leaf abnormal division and cotyledon albino as the control. The results showed that the cotyledon of sco2 mutant was albino， while the leaf grew normally. Meanwhile， the cotyledon growth and viability of the parc6 mutant were significantly lower than the wild-type， which was equivalent to the sco2 mutant， however， the double mutant sl2 with cotyledon albinism and leaf abnormal division was severely hindered. The leaf growth and viability of the parc6 mutant were also significantly lower than that of the wild type， but recovered compared to the cotyledon. The inhibited cotyledon growth phenotype of the parc6 mutant and sco2 mutant could be confirmed by the addition of carbon source to the medium， but chloroplast fluorescence parameters of sco2 were different from the wild type. The results of BN-PAGE combined with SDS-PAGE showed that the high-level structure of the photosystem of the cotyledon and leaf were normal， indicating that chloroplasts of parc6 failed to produce enough energy to affect the growth of cotyledon and leaf. The phylogenetic analysis showed that PARC6 and SCO2 coevolved， suggesting a connection between cotyledon development and chloroplast division. Our results indicated that chloroplast size was closely related to plant growth， especially the development of cotyledon， which provided a new perspective for revealing chloroplast function.
Leaf is the main photosynthetic organ， and the leaf morphology beneficial for photosynthesis has become an important breeding target. atscamp was screened from the Arabidopsis thaliana mutant library（about 6 000 lines） with wide leaves. Tail-PCR analysis revealed a T-DNA insertion at the AT1G11180 locus， which encodes a secretory carrier membrane protein（SCAMP）. RT-PCR showed that the transcriptional expression level of the gene was basically zero. The leaf width and area of the mutant were significantly larger than those of wild type plants（P<0.01）， while the crown diameter was essentially unchanged. Additionally， chlorophyll content， chlorophyll maximium fluorescence， and photosystem II potential photochemical efficiency were all increased in the atscamp mutant（P<0.05）. Correspondingly， the mutants showed significant increases in transpiration coefficient（Tr）， net photosynthetic rate（Pn）， and leaf water use efficiency（WUE）（P<0.05）. Spatial-temporal specific expression analysis of the AT1G11180 gene revealed that the gene was highly expressed only in leaves， with low expression levels in other organs， and the gene expression gradually increased with the development and maturity of plants. The results suggested that AtSCAMP might play an important role in leaf shape development.
Alfalfa（Medicago sativa） is an important forage plants. In order to effectively express foreign genes in alfalfa， by using the green fluorescent protein（GFP） as report gene and Nicotiana benthamiana as a comparison， the effects of two different vectors（the non-replicating and the BeYDV（bean yellow dwarf virus）-based replicating vectors）， and two different Agrobacterium tumefaciens strains（LBA4404 and EHA105） on the transient expression of alfalfa leaves were investigated. The results showed that the combination of LBA4404 with the replicating vector（re-vector/LBA4404） led to effective expression of GFP in alfalfa leaves. By using LBA4404 with the replicating vector， the effects of the concentration of re-vector/LBA4404 and incubation time after infection on the transient expression were also evaluated. It was found that with the increase of concentration of bacterial suspension or time post-infection， the expression level of GFP increased first but then decreased. In the leaves of alfalfa， the highest expression level of GFP was observed when the concentration of LBA4404 strain was 1.0（OD600）； and the expression level of GFP reached the peak at 5-7 d after infection. Compared with Nicotiana benthamiana， achieving the highest expression level of GFP in alfalfa might need higher concentration of Agrobacterium tumefaciens and longer incubation time after infection.
In order to explore phenotypic variation and diversity of Tilia mandshurica natural populations， and to provide reference for the selection， protection， and utilization of T.mandshurica germplasm resources. Leaves and fruits from eight T.mandshurica natural populations were measured for the determination of 11 phenotypic traits， and the phenotypic traits from different populations were compared by variance analysis， coefficient of variation and Shannon-Wiener index， and eight populations were conducted by principal component analysis and cluster analysis. Variance analysis showed extremely significant differences in leaf and fruit traits among different populations and within populations， and the percentage of variance component among populations for each trait was higher than that of within populations， and phenotypic differentiation coefficients ranged from 0.83-0.95， and the main source of phenotypic differences was from different populations. The coefficient of variation of different traits ranged from 20.0%-39.9%， indicating a large degree of variation. The Shannon-Wiener index of different traits from different populations ranged from 1.262-1.443， indicating rich phenotypic diversity populations. The 11 phenotypic traits were divided into four principal components， with a cumulative variance contribution rate of 88.46%. According to the principal component comprehensive model， the comprehensive ranking of the eight populations from high to low was Hunchun， Longtan， Huinan， Jiaohe， Dongfeng， Dunhua， Huadian and Luobei. According to leaf and fruit traits， the eight populations were clustered into three groups， among which Dongfeng and Luobei had relatively larger leaf， while Dunhua， Hunchun， Huadian， and Jiaohe belonged to the groups with larger fruit petiole and bract. The left populations， Longtan and Huinan belonged to the larger fruit group. The phenotypic traits of T.mandshurica natural populations exhibited significant variation and rich diversity， and the main source of phenotypic differences was from inter-population variation， and large gains might be achieved through selection.
To explore the reasons of color change in AmRosea1 overexpressed 84K poplar（Populus alba× P. glandulosa ‘84K’） caused by light signal， the wild type and AmRosea1 overexpressed 84K poplar were used as the materials. The anthocyanin content， chlorophyll content， soluble sugar content and POD activity under LED light， natural light， LED red light， LED blue light， and LED red and blue light treatment were measured， and the changes of physiological indexes of wild type and transgenic lines under different optical signal were determined respectively. The results showed that under different light intensities， compared with the LED light treatment， the leaves of the transgenic lines turned red， and the anthocyanin content and soluble sugar content increased， and the chlorophyll content and POD activity decreased under natural light. After 30 days of different light treatments， the LED red-blue light treatment that the antho-cyanin content increased， the soluble sugar content and POD activity decreased， and the chlorophyll content decreased slightly under LED red and blue light induction compared with LED red and blue light. Based on the experimental results， it was speculated that strong light and red and blue light quality might activate the anthocyanin biosynthesis pathway and accumulate a large amount of anthocyanins in AmRosea1 overexpressed 84K poplar， which in turn the leaves turned red.
To analyze the phenotypic traits of the floral organs of Iris lactea var. chinensis germplasm resources and to clarify the pigment composition of the petals， 22 I. lactea germplasm resources under different habitat conditions in six provinces and cities of China were used as experimental materials to systematically study the phenotypic characteristics and anthocyanin of this important ornamental part of flower organs. The phenotypic traits of the floral organs were described by RHSCC colorimetry and colorimeter colorimetry， and the mass fraction of floral pigment was determined by sodium nitrite-aluminum nitrate colorimetry and pH differential analysis， and the differences in the expression of floral pigments in different color lines were analyzed. The results showed that the flower color of 22 germplasm resources could be divided into four color families： light blue， light blue-violet， dark blue-violet and violet. The brightness（L*） of the fall and standard petals was negatively correlated with a*， positively correlated with b*， and negatively correlated with color（c*） respectively. Among the four color families， violet petals were the largest， flower branch length was the highest， and fall spot was the smallest. While light blue petals were the smallest， flower branch length was the lowest， and fall spot was the largest. It indicated that the darker the petal color， the larger the petal， and the smaller the fall spot. The mass fraction of pigment in the petals of different colors of I. lactea differed significantly. The mass fraction of carotenoid in the light blue petals was significantly higher than that in the violet color， while the mass fraction of flavonoid and anthocyanin in the violet petals were significantly higher than that in the light blue color. As the petal color deepened， the mass fraction of carotenoid decreased and the mass fraction of flavonoid and anthocyanin increased correspondingly. The correlation analysis revealed that the mass fraction of carotenoid was significantly positively correlated with fall and standard petal L*（P<0.05）， and significantly negatively correlated with fall and standard petal a* and c*（P<0.05）.The mass fraction of flavonoid was highly significantly negatively correlated（P<0.01） with fall and standard petal L* and b*， highly significantly positively correlated（P<0.01） with fall and standard petal a*， significantly positively correlated（P<0.05） with fall and standard petal c*. The correlation results between the mass fraction of anthocyanin and colorimetric parameters were similar to those of flavonoids， indicating that the mass fraction of flavonoids and anthocyanins played an important role in the coloration of I. lactea.
In order to clarify the phenotypic variation degree and regularity of flower organ traits in distant hybrids of Catalpa bungei， 12 distant hybrid species of C. bungei were used as materials， statistical analysis methods such as variance analysis， correlation analysis， and cluster analysis were used to study their phenological characteristics， inflorescence traits， flower traits， and color traits during flowering. The results showed that there were significant differences in phenological characteristics during the flowering period of the distant hybrid species of C. bungei. The hybrid of C. bungei and C. ovata was pseudo three-branch， with strong differentiation ability of flower buds， and multiple rounds of flowering in the year of grafting， and the flowering period of over 100 days， exhibited maternal traits. The floral organ characteristics of hybrid species of C. bungei were significantly different， with seven to nine rounds of lateral branches in the inflorescence axis， and the main axis was an infinite inflorescence， and the lateral branches were dichasium， and the transition from the bottom to the top was a cyme inflorescence， which was a transitional trait from a limited inflorescence of C. bungei to an infinite inflorescence of C. ovata. The variation ranges of total flower length， flower tube diameter， flower tube length， corolla width， peduncle length， pistil length， anther length， stamen length， and sterile stamen length were 35.42-50.36， 10.84-16.13， 16.57-24.68， 31.58-44.87， 9.07-31.99， 19.44-27.52， 4.85-5.89， 13.93-21.10， 3.66-6.79 mm， respectively. The variation coefficient ranged from 10.88%-31.02%， and the diversity index ranged from 1.36-1.93. Based on the nine traits， the 12 hybrids were clustered into three types： large flower type， medium flower type and small flower type. There were significant differences in flower color among C. bungei hybrids. The values of L*， a* and b* were used to cluster the labellum flower spots color of the 12 hybrids into three categories， namely pinkish purple， purplish red and purple.
Populus simonii×P. nigra is a fast-growing and cold-tolerant tree species with elite wood properties in northeast China. In order to produce a new forest germplasm with more widely planting and improved drought tolerance， this study successfully generated transgenic P. simonii×P. nigra using PsnNAC007， a key drought response transcription factor gene. Growth characteristics， drought tolerant ability， net photosynthetic rate（Pn）， transpiration rate（Tr）， stomatal conductance（Gs）， water conductance， cell morphology and wood components of overexpressed PsnNAC007 transgenic plants were analyzed respectively. The results showed that there was no significant difference in growth between transgenic and wild-type plants， but drought survival rate was increased by 26.15%. Under drought condition， transgenic plants exhibited reduced Cleaf and Tr， improved water use efficiency， and lower water conductance loss. Anatomical analysis showed that the overexpression of PsnNAC007 led to more and smaller stem xylem vessels， which were conducive to the continuous and efficient water transport in plants under drought conditions. Based on wood components analysis， lignin deposition in stems of transgenic plants was increased significantly， and monosaccharides that constituted cellulose and hemicellulose showed no significant change.
‘Populus leucopyramidalis 1’ is an excellent poplar clone with narrow crown and saline-alkali tolerance. Due to the lack of its genetic transformation system， genetic improvement could not be achieved through genetic engineering methods. In this study， an Agrobacterium mediated genetic transformation system of ‘P. leucopyramidalis 1’ was established and the high genetic transformation efficiency was achieved. Firstly， the tissue culture seedlings were subcultured at different time periods（35， 45， 55， 65 d）， and three types of tissues（leaves， petioles， and stem segments） were taken to compare the differentiation ability， and it was determined that the leaves sub-cultured after 45 d had the strongest differentiation ability， with a proliferation ratio of 8.77. Then， leaves sub-cultured after 45 d were used for genetic transformation， and the effects of different infection conditions on the transformation rate were examined. Orthogonal experiments were established with three gradients of bacterial concentration， infection time， and co-culture time to screen the best levels of these three factors， and the transgenic strains were identified through PCR detection and GUS staining. The results showed that the optimal combination for the genetic transformation system of ‘P. leucopyramidalis 1’ was bacterial concentration OD600=0.4， infection-time 15 min， and co-cultivation time 2 d could reach the highest transformation rate 54.23%. Finally， the ‘P. leucopyramidalis 1’ transgenic strain of BtCry3Aa insect resistant gene using this genetic transformation system was obtained， and the results proved that this system could be an effective method for genetic improvement of ‘P. leucopyramidalis 1’.
To protect germplasm resources and provide technical support for native garden species， the breeding system and hybrid affinity of wild Rhododendron irroratum were studied. The experiments included flowering biological characteristics， the characteristics of breeding system and the cross pollination with fine horticultural varieties of Rhododendron. The process of pollen germination and pollen tube growth were observed by fluorescence microscope， and the fruiting and seed setting were calculated. The results showed that （1） the flowering time of R. irroratum dewdrop was from late April to late May， and pollen viability and stigma receptivity decreased gradually with the extension of flowering time. （2）Hybridization index（OCI） was 3， P/O value was 343.47. （3）The main pollinator was Apis cerana. The breeding system was facultative outbred， self-compatible， requiring pollinators. （4）No apomixis was found in artificial pollination， which could automatically self-pollinate. The fruit setting rates of different strains cross-pollination， strains cross-pollination and self-pollination were 46.96%， 45.03% and 37.16% respectively. The average fruit setting rate of artificial pollination was basically consistent with that of natural pollination. （5）The hybrid incompatibility was observed in the parent for artificial cross pollination. Fluorescence microscopy revealed callose embolism in the pollen tube of the mother， which prevented the tube from extending to the ovary. Through observation， it is found that the difficulty of cross compatibility lies in pollen tube growth process.
