A likely autotetraploidization event shaped the Chinese mahogany(Toona sinensis)genome

Chinese mahogany(Toona sinensis) is of considerable medical and economic importance, and its genome has been deciphered. However, the process underlying its polyploidy is unclear, and the chromosomal evolutionary trajectory is poorly understood. Here, by reanalysing the T.sinensis genome, we found evidence of a tetraploidization event(T. sinensis special tetraploidization, TST) that occurred approximately 15-17 million years ago(MYA) after the core eudicot-common hexaploidization(ECH or gamma) event. We characterized the synonymous nucleotide substitution rates(Ks values) of collinear genes and found that T. sinensis genes affected by the TST evolve at a slower rate than Acer yangbiense genes. Furthermore, we identified homologous genes related to polyploidization and speciation and constructed multiple alignments with different reference genomes. Notably, the significant balance of gene retention and loss characterized in the two TST-derived subgenomes suggests an autopolyploid nature of the TST. Moreover, we deduced the chromosomal karyotypes of the two subgenomes and identified 7chromosomal fusions that have shaped the T. sinensis genome;more information is available on a newly constructed karyotype platform(http://www.cgrpoee.top/Toona_sinensis/index.html). The T. sinensis genome preserves the ancestral chromosome structure of dicotyledons well and could serve as a good reference for understanding genomic changes in other Meliaceae and Sapindales plants. In addition, we verified that tandem duplication and the ECH have promoted the expansion of terpene synthase(TPS) genes;conversely, the TST seems to have inhibited expansion of these genes. This present effort has clarified the polyploidy events of the T. sinensis genome, filled gaps in the history of karyotype evolution, and laid a solid foundation for further genomic studies in the Meliaceae research community and beyond.

Experimental Research on Four Season Soilless Cultivation of the Sprouting Seedlings of Toona sinensis in Chongqing

Using seed sowing cultivation method, the four-season soilless cultivation of the sprouting seedlings of Toona sinensis was carried out with different germination accelerating treatments, cultivation substrates, cultivation environment and management technologies by using the corresponding treatment methods in different seasons, so as to produce the sprouting vegetable products of T. sinensis which was not restricted by seasons. The test results showed that using the mixed substrate of pedite and vermiculite in winter and spring can keep moisture but not too high, and the produced sprout vegetable had good quality and high yield.

Design and Construction of Rainwater Harvesting and Water-saving Irrigation System of Toona sinensis on Mountain Slopes

In order to collect rainwater and resist drought to enhance the utilization rate of rainfall and water resources, through project rainwater harvesting measures, the total annual rainwater harvesting amount of the six greenhouses was calculated according to annual average precipitation 542.2 mm, up to 1 095.7 m^3. The upper natural slopes of cultivated land were as rainwater harvesting areas, and total annual rainwater harvesting amount was 49 242 m^3 on the mountain slopes with an area of 73.37 hm^2, while total water storage amount was 39 394 m^3 in theory, so it could meet water use for the irrigation of 26.28 hm^2 of T. sinensis land. To be convenient for rainwater harvesting, irrigation and supplying water to the water-saving cellars, one pert-cut and part-fill reservoir （which was 470 m^3 in volume） was built on the mountain slopes at the right rear of the greenhouses, and their altitude difference was 50 m. The reservoir was sealed and was built with reinforced concrete. Water-saving cellars were distributed in front and the middle and at the back of two rows of greenhouses, and they were connected with each other. The reservoir could supply water to the water-saving cellars and also collect water by mountain slopes, from the lower water-saving cellars or deep wells. Two rainwater hervesting ditches that were 1 650 m in length were at the lower edge of arable land in the upper reaches of slopes to intercept rainfall runoff and make it flow into channels and then the sedimentation tanks. The total annual rainwater harvesting amount of the reservoir and water-saving cellars was 1 222.5 m^3.

Bioactivities of Extracts from Toona sinensis against Sitophilus zeamais

[ Objective ] The repellent activities and contact toxicity of extracts from Toona sinensis against Sitophilus zeamais were studied. [ Meth- od] 95% alcohol, petroleum ether and dichloromethane were selected to extract the active components from the leaves and barks of T. sinensis, respectively. And then the extracts were prepared at 0.6, 0.3, 0.15 g/ml to study the biological activity against S. zeamais in lab. [ Result J The petroleum ether extracts from the leaves of T. sinensis had significantly repellent effects on S. zeamais, but the extracts from T. sinensis with three solvents had no obvious contact toxicity against S. zeamais. [ Conclusion ] The petroleum ether extracts from S. zeamais had certain repellent activity.

香椿(Toona sinensis)微卫星富集文库构建及特性分析

采用Dynal磁珠富集法构建了香椿微卫星富集文库,通过测序结果对文库的特性进行了分析。实验使用改良CTAB法提取香椿基因组DNA,用（AC）8、（AG）8和（ATG）123种带有生物素标记的探针与香椿基因组DNA的酶切片段进行杂交,将磁珠捕获的含有微卫星序列的DNA片段插入p MD 18-T载体,并转入感受态细胞Trans 5α构建克隆,经筛选后得到含356个克隆的香椿基因组微卫星富集文库。从富集文库中挑选插入片段长度为400-800 bp的128个克隆进行测序,其中含有SSR的序列77条,得率达60.16%,其中完美型占82.69%,非完美型8.65%,混合型8.65%。上述结果为SSR位点的进一步开发奠定了基础。

Analysis of Volatile Compounds and Identification of Characteristic Aroma Components of <i>Toona sinensis</i>(A. Juss.) Roem. Using GC-MS and GC-O

In this study, volatile compounds present in Toona sinensis (A. Juss.) Roem (TS) were investigated and their characteristic aromatic components were identified using Headspace Solid-phase Microextraction (HS-SPME) followed by Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-Olfactometry (GC-O). The optimum conditions for extracting the volatiles from TS were achieved with the experimental parameters including the use of a 65 μm polydimethylsiloxane/divinyl benzene (PDMS/DVB) fibre, an extraction temperature of 40℃ and an extraction time of 30 min. Under these conditions, 56 volatile compounds were separated and 53 were identified by GC-MS. Among them, 21 sulfide compounds (42.146%) and 27 terpenes(55.984%) were found to be the major components. The sample was analyzed by GC-O and 26 elutes were sniffed and their sensory descriptions evaluated by an odor panelists. Analysis of the data indicated, two compounds cis and trans isomers of 2-Mercapto-3,4-dimethyl-2,3-dihydrothiophene were major contributors to the characteristic aroma of TS.

Experimental Study on Cultivation of Multi-head Seedlings of Toona sinensis in Chongqing

Seedlings of Toona sinensis were planted in seeding and breeding ways to increase the yield of T. sinensis by raising the number of lateral branches of T. sinensis seedlings by means of cutting and pinching through sowing and breed- ing in containers and sand bed nursery. The results showed that： after cutting and pinching, seedlings with multi-lateral branches could be formed. The cutting treat- ment in the container had a small number of seedlings with over 2 lateral buds, and the lateral buds were weak. Some of the weak lateral buds disappeared with the growth going on, showing poor growth performance. The pinching treatment in the sand bed nursery found a large number of seedlings with more than 2 lateral buds, and the lateral buds could grow into lateral branches, forming the T. sinensis seedlings with multi-lateral branches. Proceed to cutting processing, the secondary and third-level lateral branches came into being, which could make the seedlings of T. sinensis have multi-head tree shape in 2-3 years.

Lactam Triterpenoids from the Bark of Toona sinensis

Three new limonoid-type triterpenoids,namely toonasins A–C(1–3)with a rare lactam E ring,along with six known compounds(4–9)were isolated from the barks of Toona sinensis.The structures of new compounds were elucidated by interpretation of spectroscopic data,and the relative configuration of compound 1 was further characterized by X-ray crystallographic analyses.The isolated compounds were evaluated for their cytotoxic activities against five human tumor cell lines(HL-60,SMMC-7721,A-549,MCF-7 and SW480),and compounds 3 and 5 showed weak cytotoxicities.

Research of Protected Cultivation Techniques of Toona sinensis on Mountain Slopes

In order to prolong the supply period and increase the economic value of Toona sinensis,the protected cultivation of T. sinensis was carried out on mountainous slope to achieve stagger-season planting and the year round supply. The results showed that in late October to midNovember,the temperature was moderate( 1-10℃) and suitable for the lifting of seedlings and temporary planting dormancy. The line spacing of rooted seedlings in greenhouse was( 22-24) cm ×( 4-5) cm and planting density was 900 000-1 200 000 seedlings/ha. The line spacing of seedlings was( 14-13) cm ×( 3-4) cm and planting density was 1 950 000-2 100 000 seedlings/ha. T. sinensis began to sprout at 8-10℃ and stretch at 10-12℃. When the temperature was stable at 14℃ or above,T. sinensis started bolting and emerging leaves. The terminal buds sprouted in 40-50 d for the T. sinensis planted in greenhouse with the day temperature of 15-22℃ and night temperature over 10℃; the terminal buds sprouted in about 15 d for those planted in the greenhouse with day temperature of 20-25℃ and night temperature over 10℃. T. sinensis could be picked 3 times when planted in greenhouse,and the yield was about 24 720 kg/ha.

Study on the relationship between Toona sinensis Roem stand productivity and site conditions in Sichuan Basin

According to the relationship between Toona sinensis Roem stand volume,productivity and forest age,site conditions,stand density and other factors,through selecting 8 representative cities or counties,using standard investigation and stem analysis method,this paper makes relatively systematic research about the Toona sinensis Roem plantation accumulation,productivity,and the relationship between them and site conditions.Through comparative analysis indicators of multiple site conditions,this paper expects to give a more comprehensive picture about the source of accumulation and productivity difference.

Effect of Low Temperature Stress on Protein Content of Toona Sinensis Seedlings and Expression of Specific Protein

[Objective] The paper was to study the changes of protein content and component in leaves of Toona Sinensis under low-temperature stress.[Method] Potted experiment was adopted,and SDS-PAGE electrophoresis was also used to analyze the dynamic changes of protein in T.Sinensis leaves.[Result] Low temperature stress could change the content and component in leaves of T.Sinensis,but different provenances had different performance under different temperatures,so did the same provenance under different stress periods.SDS-PAGE electrophoresis results indicated that the change law of provenances of Xixia of Henan and Nanjing of Jiangsu with stronger cold resistance was similar,showing the change trend of "increase-decrease-increase".Protein was greatly expressed after stress for 1 d,the color of band became darker;the content gradually decreased in the following second and third day,and the color of bands was lighter;the content began to increase at the forth day.Two provenances induced the specific proteins with molecular weights of 27.6 and 22.5 kD,respectively.The soluble protein content of provenance of Xiapu of Fujian with relatively weak cold resistance was gradually increased,but no new protein bands were induced.The changes of protein band color of various provenances in SDS-PAGE electrophoresis was basically consistent with the changes of protein content,the provenance with stronger cold resistance could induce the production of specific proteins.[Conclusion] The study provided theoretical basis for under the molecular mechanism of plant cold resistance,which had great significance in theory and practice.

Effects of Drying and Blanching on the Quality of Toona sinensis

[Objective]To explore the best T.sinensis processing technology.[Method]The T.sinensis was treated by hot wind drying,freeze drying and blanching,and the contents of ascorbic acid,total phenolics and nitrite were determined respectively before and after the treatment to be a standard to evaluate the influence of different processing methods on the quality of T.sinensis.[Result]Both drying and blanching produced certain impact on the contents of all three components,among which the content of ascorbic acid was slightly influenced by vacuum freeze drying and short-time blanching,but greatly affected by long-time blanching and hot wind drying;the loss rate of polyphenols was above 60% when the hot wind drying,freeze drying and blanching lasted for more than 5 min,while it experienced little change under short-time blanching;hot wind drying and blanching may greatly reduce the content of nitrite,however,the vacuum freeze drying even improved the content,which would produce adverse impact on food safety.[Conclusion]Short-time blanching is the best method to process T.sinensis,it can effectively reduce its content of nitrite and retain the nutrients.

Pb胁迫对红椿(Toona ciliata Roem)生长发育及Pb富集特性的影响

采用盆栽试验研究了酸性紫色土、钙质紫色土和冲积土上生长的一年生红椿实生苗暴露在不同浓度Pb胁迫（0、200、450mg·kg-1和2000mg·kg-1）条件下的叶长、叶面积、生物量、各器官Pb含量特征和富集程度,并分析了红椿对Pb污染的耐性和转移效率。3种土壤下红椿都能生长,但相同浓度Pb胁迫下其在钙质紫色土中生长状况最佳,在冲积土中生长状况最差。随Pb浓度增大红椿叶片生长受到明显抑制,当土壤中Pb浓度在2000mg·kg-1时,其叶长和叶面积与对照差异极显著（P〈0.01）;Pb胁迫使得红椿根茎比发生明显的变化,还加大其叶的凋落程度,同时整株生物量随着Pb胁迫浓度的增大呈极显著降低趋势（P〈0.01）,但在土壤Pb浓度最大时其生物量仍达到对照的81.47%以上。红椿体内Pb含量与土壤Pb浓度成正相关（P〈0.01）,其6个器官中细根Pb含量最高,粗根次之,而地上部分的Pb含量较低且差异不大。红椿耐性指数值在0.67~1.06之间,表现为随Pb胁迫浓度增大,其耐性呈下降趋势。红椿富集系数与转移系数都较小且小于0.3。这些结果表明,红椿能在Pb污染较严重的土壤中较好的生存,可作为Pb污染区域潜在的土壤修复树种。

Cultivation Density of Toona ciliate

ln order to discuss the optimum seedling density of Toona ciliate, different seedling densities were studied. The results showed that seeding height and basal diameter decreased and quality of the seedlings declined with the increase of seedling density. The reasonable density of seedlings is key to cultivate high-quality seedlings and achieve the best seedling efficiency. The optimum density was 30 plants/m2 for the first class seedlings of biennial seedlings, and the optimum density of l and ll seedlings for production afforestation was 40 plants/m2.

桂西北红椿(Toona ciliata)群落结构与更新特征

红椿为我国的濒危保护物种。以广西西北部红椿(Toona ciliata)主要集中地群落为研究对象,利用在隆林县、西林县和田林县的野外样地调查数据,分析广西红椿群落物种组成、多样性、结构及红椿更新特征。结果表明:广西红椿群落主要物种包括枫香(Liquidambar formosana)、苦楝(Melia azedarach)、银合欢(Leucaena leucocephala)、粗糠柴(Mallotus philippensis)、杜茎山(Maesa japonica)、马莲鞍(Streptocaulon griffithii)等。隆林县具有较高的科、属、物种丰富度,但乔、藤、草及总物种丰富度在3个地点间无显著差异;田林县和隆林县均在较低径阶和高径阶中具有较高的物种丰富度和个体多度,而西林县在低径阶中有较高的物种丰富度,但差异均不显著;红椿野生种群实生苗更新困难,在3个调查地点红椿实生幼苗平均仅为1.3株,在隆林调查点甚至未发现有更新的幼苗。因此,在保护红椿种群的同时,可适当进行红椿幼苗的人工补植。

Research Progress in Cultivation and Pharmaceutical Chemicals of Toona ciliata and Toona ciliata var. pubescens

Toona ciliata and Toona ciliata var. pubescens are rare timber species. In China, Toona ciliata and Toona ciliata var. pubescens distribute sporadical y with smal popuIation size but have huge deveIopment potential. The paper reviewed the research progress of their seedIing breeding, nutrient characteristics, fertiIization technoIogy, afforestation design, timber utiIization, chemistry and pharmacoIogy, and then Iooked into the future research and utiIization of Toona ciliata and Toona ciliata var. pubescens.

Tissue Culture of Toona ciliata

In this study, a screening experiment was carried out among MS, WPM, DCR, MT, B5 and N6. The results showed that for proliferation culture of Toona ciliate, the optimum basic medium was WPM, and the optimum medium was WPM ＋ 6-BA 0.5 mg/L ＋ IBA 0.05 mg/L. The proliferation coefficient reached 4.29. The optimum rooting culture medium was 1/2 MS ＋ IBA 0.5 mg/L ＋ NAA 0.5 mg/L with rooting rate of 100%. In the optimum rooting ＇culture medium, the roots of T. ciliate developed neatly, and the seedlings grew well.

镉胁迫对红椿(Toona ciliate Roem.)幼苗生长及碳、氮、磷、钾累积与分配的影响

为了解镉(Cd)胁迫对红椿(Toona ciliata Roem.)生长及养分[碳(C)、氮(N)、磷(P)和钾(K)]吸收的影响,采用盆栽控制试验研究了不同浓度Cd处理[0(对照)、10、20、40、80、160 mg·kg^(-1)]对其幼苗生长发育、生物量以及养分积累与分配特征的影响。结果显示:与对照相比,红椿幼苗生长特性指数(如叶数、叶长、叶宽、根长及地径和株高)与根、茎、叶生物量随Cd浓度增加而降低,但低Cd处理(<40 mg·kg^(-1))对各器官指数、株高及总生物量无显著影响(P>0.05)。随着Cd胁迫浓度增加,根、茎、叶中Cd浓度逐渐升高,且根大于茎;根K、茎K、叶K和叶N累积量随胁迫浓度增加呈先升后降,而根C、根N、茎N、根P和叶P累积量则逐渐降低。此外,茎C、叶C和茎P在低Cd处理时无显著差异,但较高Cd胁迫处理(≥40.00 mg·kg^(-1))则显著抑制并改变其累积与分配格局。红椿幼苗具有一定的抗Cd胁迫能力,但较高浓度Cd胁迫(≥40.00 mg·kg^(-1))显著影响了红椿幼苗的生长特性及其养分格局。

Study on Cutting Propagation of Toona ciliata Clones

Cutting propagation rhizogenesis of Toona ciliata clone cutting orchard were studied, and the results were as fol ows： Rooting type included both cal us rooting and cortex rooting. About 17 in 22 of clones were dominated by cortex rooting, accounting for the 77% of clones. There were 5 clones which occurred with both cal us rooting and cortex rooting during rooting process. The rooting efficiency index （REI） showed a positive correlation with the rooting rate. Under natural tem-perature condition, keeping moisture and shading, we found that the highest survival rate occurred in early June, September, and October.

Research on Genetic Physiological Ecology of Precious Species: Toona ciliata and Toona ciliata var. pubescens

Toona ciliata and Toona ciliata var. pubescens are timber species of national second-class protective plants. In China, Toona ciliata and Toona ciliata var.pubescens distribute sporadically with small population size but with great development potential. Plus selection on phenotype of Toona ciliata and Toona ciliata var.pubescens, molecular genetic marker of Toona ciliata var. pubescens, research progress in physiology and ecology of Toona ciliata and Toona ciliata var.pubescens were summarized in this paper. Suggestions and prospect forecast were proposed for relative research and utilization.