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.

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.

香椿老叶开发利用的研究进展

香椿[Toona sinensis(A. Juss.)Rome.]老叶含有蛋白质、黄酮、多糖、皂苷、生物碱等物质,具有开发利用的价值。综述了香椿叶不同生长期成分变化和黄酮类物质、膳食纤维、多糖、皂苷类物质提取分离的研究进展,并对香椿老叶的开发利用提出了建议。

香椿叶用蔬菜种子育苗及苗期生长规律研究

经香椿(Toona sinensis)叶用林一年生实生苗苗期生长试验分析,选用Logistic生长曲线方程拟合研究其苗期生长规律。按苗高和地径生长速率将其生长划分为出苗期、生长初期、生长盛期和生长后期4个阶段,香椿叶用林苗期生长呈“慢-快-慢”的生长规律。生长量集中在盛期阶段,苗高生长量占总生长量的70.48%,地径占78.05%。

生态公益林下香椿栽培技术

为提高生态公益林的资源利用率和经济效益,本实验开展不同坡向、不同截干方式和不同栽培模式对生态公益林下香椿(Toona sinensis)产量的影响,探索林下香椿高产的技术方案,为我区低丘陵地生态公益林林下种植香椿提供技术支撑。试验结果表明,种植在南坡的平均单株产量最高,其次是西坡、西南坡,东坡的平均单株产量最低;不同的截干方式以摘除顶芽的方式平均单株产量最高;原地挖坎种植的平均单株产量高于控根器种植的平均单株产量。

广西不同种源香椿苗期及造林前期生长性状分析

为了研究广西香椿(Toona sinensis)不同种源和家系的苗期及造林前期生长性状,为广西香椿的良种选育做好基础,并为香椿育苗和造林技术提供参考,用马山县、隆安县和德保县等10个种源(33家系)的香椿半同胞种子进行育苗,并用育出的苗木营建子代测定林,测定苗期和造林后香椿的胸径(地径)和树高。结果表明:0.5年苗期时,长势较好的种源为隆安县、靖西市和乐业县,长势较好的家系为25、30、12和8;造林1年时,长势较好的种源为乐业县、金城江区和都安县,长势较好的家系为13、15和16;造林2年时,长势较好的种源为武鸣区、都安县、和马山县,长势较好的家系为13、6和31;不同香椿种源及家系造林后胸径和树高增长量存在较大的变幅,造林第2年的胸径增长量和第1年的相似,造林第2年的树高增长量明显比第1年多。可得出结论,都安县、马山县种源以及13家系在造林第1、第2年的生长均表现较好,初步认为是适应南宁市区域的最优种源或家系。

香椿查尔酮异构酶基因的克隆及在幼苗中的表达分析

查尔酮异构酶是调控植物花青素生成的关键酶,本研究利用PCR扩增技术从香椿叶片中克隆得到香椿查尔酮异构酶基因TsCHI。序列分析发现TsCHI基因开放阅读框全长717 bp,共编码238个氨基酸,属于亲水性、酸性蛋白。系统进化分析表明TsCHI蛋白属于TypeⅠ型CHI蛋白,与无患子目的槭树(Acer×freemanii)、橄榄(Canarium album)、龙眼(Dimocarpus longan)、柑橘(Citrus sinensis)的亲缘关系较近。实时荧光定量PCR结果表明,TsCHI在香椿幼苗茎中的表达量显著高于根与叶中的表达量,叶比根中的表达量高,但差异不显著;38℃高温胁迫、200 g/L PEG-6000溶液干旱胁迫、200 mmol/L NaCl溶液盐胁迫条件下,TsCHI基因的表达量均高于对照,且随着处理时间的延长,表达呈上升趋势。研究结果为香椿幼苗的开发利用和通过基因工程手段提高幼苗中黄酮类物质的含量提供了理论参考。

香椿叶化学成分及药理作用研究进展

在系统查阅相关文献的基础上,对香椿(Toona sinensis)叶的化学成分和药理作用研究进展进行总结,为深入研究和合理利用提供依据。