Evaluation of the Characteristics of Virus-free Sweetpotato and Its Use in Hybridization

Application of virus-free sweetpotato is a breakthrough of sweetpotato production. Several popular varieties were adopted to study their yield increase potential and their use in breeding in this research. The results showed that after virus-elimination, all varieties had a yield increase ranging from 14.95% - 91. 61% and marketable quality improvement, despite the changes in location and season. The changes of dry matter content and disease resistance were not significant. Virus-free sweetpotato performed vigorous vine growth and strong dry matter assimilation ability. Virus-free parents had a slightly high seed setting percentage, but its flowering ability and performance of off-springs were similar to that of its check plants.

Detection of Ratoon Stunting Disease in Virus-free Seedcane via Real-time Fluorescence Quantitative PCR

This study was to develop the real-time fluorescence quantitative PCR technique for detecting the ratoon stunting disease （RSD） in virus-free seedcane seedlings. Healthy tissue culture seedlings were obtained from six plants of sugarcane ROC22, which had been confirmed RSD-positive by detecting the sugarcane juice, by employing the sugarcane seedlings production protocol. Real-time fluorescence quantitative PCR was used to detect RSD pathogens in tissue culture sam- pies. The results showed that target fragment of RSD pathogens was not found in all 10 samples in real-time fluorescence quantitative PCR, with the Ct values of 37 - 39. The healthy tissue culture sugarcane seedlings do not carry RSD pathogens, indicating that adopting healthy seedcane seedlings production technique could thoroughly get rid of RSD pathogens.

A Preliminary Study on Tissue Culture and Rapid Propagation of Virus-free Plantlets of Benihoppe Strawberry

[ Objective] This study aimed to investigate the tissue culture and rapid propagation techniques of Benihoppe strawberry. [ Method] Shoot tips of new stolons of Benihoppe strawberry were used as experimental materials to analyze the effects of media type, cytokinin type and concentration, carbon source type and concentration, and light intensity on tissue culture and propagation of Benihoppe strawberry. [ Result] MS was the optimal media for plantlet propagation. In the media containing 1.2 ing/L BA （with addition of 0.1 mg/L NAA）, fresh weight, dry weight and propagation coefficient of strawberry plantlets reached the maxi- mum, which were 2.259 g, 0. 221 g and 12.4, respectively. The optimal carbon source was 30 g/L sucrose, and the optimal light intensity was 1 600 lx. [ Conclu- sion] The best media for tissue culture and rapid propagation of Benihoppe strawberry was MS ＋ BA 1.2 mg/L ＋ NAA 0. 1 mg/L ＋ sucrose 30 g/L ＋ agar 8 g/L. This study provided scientific basis for large-scale production of Benihoppe strawberry.

Expression of Invertase Genes in Virus-free Sugarcane

Virus-free sugarcane seedlings have improved biomass and sucrose content compared with ordinary seedlings, and sucrose invertases are key enzymes regulating sugarcane growth and sucrose accumulation. In this study, the differences in the expression levels of 3 invertase genes, CWI, SAI and NI, between virus- free and ordinary sugarcane seedlings were analyzed. Compared with ordinary sugarcane plants, the expression of CWI was mainly up-regulated in immature leaves and stems at elongation stage and leaves and immature internodes at maturation stage, and especially, greatly up-regulated in immature interuedes at maturation stage of virus-free plants. The expression of SAI and NI were mainly up-regnlated in leaves and immature internedes of virus-free plants at maturation stage, which might be beneficial to sugar accumulation and rapid utilization of monosaccharide in the stalks of virus-free plants. It is further indicated that virus-free treatment could significantly improve the expression of sucrose invertases at late growth period, and might facilitate the increase of plant biomass.

Study on Virus-free Breeding Technology of Potato Microtuber

It is the simplest,fastest and effective way to improve the yield level of potato by selecting high quality virus-free seed potato for field production and maintaining the original characters of virus-free minituber. Microtuber is featured by small volume,no pathogen,convenient storage and transportation,which can be induced in summer with high temperature and humidity,and overcome a series of problems such as poor survival rate of transplanted test-tube plantlets,and easy pollution of cutting tips. Therefore,it can replace conventional test-tube plantlets directly for reproduction. Meantime,if minitubers are sown ahead of time using cold frame,the growth stage of potato minituber will avoid the occurrence period of aphids. The use of gauze cover for insect prevention has good effect on maintaining the excellent characters of microtuber. The yield and quality of virus-free potato are greatly improved by means of virus-free culture of shoot tip seedlings,subculture propagation of virus-free seedlings,induction of microtubers by dark culture,cultivation of breeder’s seeds in greenhouse and screenhouse to preserve the characters of potato.

Correlations between delayed fluorescence of chlorophyll, metabolism and yield of plants. III. Influence of viral infection on field plants and new technology of clone selection of virus-free planting potato

At the end of potato plants vegetation virus in-fection induced both decrease in maximum amplitude of delayed fluorescence maximal amplitude and increase half time of its decrease, as well as reduction in the amount of stems, plants’ height and assimilation area surface, yield, acceleration of plants development and their early die-off. The differences of DF pa-rameters and yields between strongly and weakly infected plants increase in case of a combined virus infection. In industrial test of the selection of virus-free planting potato by the use of DF parameter, a rise in the yield and de-crease degree of viral infection of crops was obtained.

Steps To ward HIV Cure Two more HIV-infected patients appear to be virus-free after bone-marrow transplants

THIS year＇s International AIDS Society Conference on HIV Pathogenesis, Treatment and Preven-／tion, held in Kuala Lumpur, Malaysia, made major headlines when Timothy Hendch, an American doctor, announced that two more cancer patients may have been cured of HIV after receiving bone-marrow transplants to treat lymphoma. Both patients had been taking retroviral medication, and continued to do so after the transplants as their viral levels sank until doctors were unable to find any traces of HIV in the patients＇ blood.

Design and experiment of conical diversion virus-free potato minituber precision seed-metering device

In order to accelerate the development of sowing mechanization of virus-free potato minituber,a conical diversion virus-free potato minituber precision seed-metering Device was designed according to the structural characteristics and agronomic requirements of virus-free potato minituber.The device is mainly composed of conical turntable,transmission shaft,outer baffle of seed-metering Device,baffle,seed outlet,seed cleaning device,type hole,etc.The working principle of conical diversion precision seed-metering device for virus-free potato minituber was expounded,and the stress analysis of virus-free potato minituber in each region was carried out.By EDEM discrete element simulation software,the structure of the type hole is optimized to determine the optimal structure of the type hole and according to the physical characteristics of virus-free potato minituber,the single factor experiments of the effects of length of type hole,cone disc speed and cone disc angle on seed filling performance were completed.The orthogonal regression test was carried out with the length of type hole,cone disc speed,and cone disc angle as the test objects,and the leakage rate and qualified rate as the response indexes.The regression models of leakage rate,replay rate,and qualified rate were established,and the parameters of the regression model were optimized.The optimal parameter combination is that the length of type hole is 33.61 mm,the cone disc speed is 6.35 r/min,and the cone disc angle is 26.59°.Bench test was carried out under the optimal conditions,the leakage rate was 3.80%,the replay rate was 0.80%,and the qualified rate was 95.40%,which was basically consistent with the prediction results of the regression model,and met the requirements of precision sowing of virus-free potato minituber.

高山红景天愈伤组织的超低温保存

高山红景天叶片在附加6-BA2mg·L-1和NAA0.5mg·L-1的改良MS培养基中诱导出愈伤组织,将愈伤组织放入10%DMSO+0.5mol·L-1山梨醇的冰冻保护剂中,4℃冰箱中放置8h,然后以1℃.min-1的降温速度降至-40℃,停留2h后投入液氮保存,在40℃水浴中化冻。冻存后的愈伤组织用液体培养基MS+6-BA2mg·L-1+NAA0.5mg·L-1反复冲洗后,转入固体培养基中进行暗培养,2周后转入光照(2000lx)培养。5周后观察到高山红景天愈伤组织呈鲜绿色,长势较为旺盛,愈伤组织存活率达到75.64%。冻存后的愈伤组织可诱导成苗。

牡丹试管苗生根研究进展和展望

从生根培养基、蔗糖浓度、环境因子、生根移栽等方面论述了牡丹试管苗的生根研究进展,提出今后的研究可以从生理生化及细胞学方面入手探索牡丹试管苗的生根机理。

无籽西瓜子叶离体培养及植株再生研究

以无籽西瓜黑蜜5号无菌苗子叶为材料,对组织培养植株再生的条件进行了详细的研究。研究结果表明:子叶芽诱导的最佳培养基配方为MS+6-BA3.0mg/L+NAA0.1mg/L。芽的诱导需要先在黑暗条件下启动,生长分化则须在光下进行。适宜的生根培养基配方为1/2MS+IAA0.4mg/L和1/2MS+IBA0.3mg/L。试验初步建立了适用于无籽西瓜遗传转化和快速繁育的子叶再生系统。

绒毛白蜡茎段的组织培养及植株再生

以绒毛白蜡幼嫩茎段为材料,研究了其组织培养和植株再生技术。结果表明:绒毛白蜡组织培养适宜的基本培养基为WPM,幼嫩茎段芽诱导的适宜培养基为WPM+TDZ 1.0 mg/L+NAA 4.0 mg/L,幼芽形成根的适宜培养基为WPM+IBA 1.0 mg/L+NAA 0.5 mg/L。该研究结果为绒毛白蜡的细胞工程和基因工程及新品种的快速繁殖奠定了基础。

鹿角杜鹃嫩叶离体培养和高效植株再生

以鹿角杜鹃新生嫩叶为外植体,通过均匀设计法筛选其最适合的愈伤组织诱导、愈伤组织再分化及生根培养基。结果表明,最适合鹿角杜鹃嫩叶愈伤组织诱导的培养基为:DR+ZT2.60 mg·L-1+IAA0.75 mg·L-1,诱导率为99.2%;愈伤组织再分化培养基为:DR+ZT3.35 mg·L-1+IAA 0.05 mg·L-1+KT 1.90 mg·L-1,分化率为99.9%;生根培养基为:1/4DR+KT0.10 mg·L-1+IBA0.04 mg·L-1,生根率达98.0%以上。以再生植株茎节为材料进行快繁的结果表明,在38 d的培养周期内,每段增殖倍数平均达7以上,再生率为96.5%。再生植株的炼苗栽培成活率达98.5%以上,并成功建立了鹿角杜鹃嫩叶的愈伤组织诱导、再分化芽苗和高效植株再生体系,所建立的高效植株再生体系可满足于鹿角杜鹃工厂化育苗的需要。

光质对茅膏菜试管苗生长和槲皮素含量的影响

在不同光质下培养茅膏菜试管苗,观察其生长情况,并采用高效液相色谱法测定槲皮素含量。结果显示,试管苗在白光下长势最好,红光下长势其次,蓝光和绿光下长势较差;不同光质下茅膏菜试管苗槲皮素含量依次为:绿光(0.7261%)>蓝光(0.4730%)>红光(0.4650%)>白光(0.4437%),在绿光下培养的茅膏菜试管苗槲皮素含量显著高于其他光质。

诸葛菜试管苗的光合特性及其对CO_2浓度升高的响应

用Li-840 CO2/H2O气体分析仪对诸葛菜试管苗的光合特性及其对CO2升高的响应进行研究。结果表明:诸葛菜试管苗的光合速率日变化不大,午间没有明显的“午休”现象。在不同光源下实际光合速率的比较,在相同的光强下LED-红光下的试管苗的光合速率最高,LED-蓝光次之。正常大气条件下,LED-蓝光在70μmol/(m2.s)光强下的诸葛菜试管苗的CO2饱和点为5 058μmol/mol,CO2补偿点为266μmol/mol。

荻植株再生体系建立

以成熟种子为外植体建立了荻植株再生体系。荻成熟种子经20%"84"消毒液处理20 min,接种于MS+4%蔗糖(pH 5.5)培养基中培养5 d,萌发率为92%,褐化率为8%,污染率为0。萌发种子继代转入愈伤诱导培养基MS+1mg/l 6-BA+1mg/l 2,4-D+0.5mg/l NAA+4%蔗糖(pH 5.5),光照条件下愈伤组织诱导率为86%,黑暗条件下愈伤组织诱导率64%。荻愈伤组织在MS+1mg/L 6-BA+0.1mg/L2,4-D+0.5mg/L NAA+4%蔗糖(pH 5.5)进行不定芽诱导,不定芽发生率为91%。无根丛生芽继代转入不定根诱导培养1/2MS+0.25mg/L IBA+0.25mg/L NAA+4%蔗糖(pH 5.5),5天可见不定根形成,15天后不定根发生率为92%。研究还发现,荻种子萌发后可直接继代转入不定芽分化培养基形成健壮不定芽,不定芽诱导率为95%。

龙眼限制生长保存EC体胚再生植株的RAPD分析

利用筛选的10条随机引物,对龙眼胚性愈伤组织(embryogenic callus,EC)限制生长保存后体胚再生完整植株基因组DNA进行扩增。结果表明,龙眼EC不同保存年限(5个月、3年、13年)体胚再生完整植株RAPD谱带存在一定差异,保存5个月的EC体胚再生完整植株共扩增出371条谱带,其中有37条变异谱带,变异率为9.70%;保存3年的EC体胚再生完整植株共扩增出352条谱带,其中有47条变异谱带,变异率为13.07%;保存13年的EC体胚再生完整植株共扩增出365条谱带,其中有55条变异谱带,变异率为15.07%。由此可见,长期限制生长保存后EC再生的体胚苗变异率趋于稳定。

组培芋田间中试

对多子芋(武芋1号)试管苗和试管球茎的田间中试生长情况进行比较,结果表明,6月下旬～7月中旬武芋1号试管苗植株生长速度较其常规芋种快,到7月中旬,与常规芋种相当,7月下旬～8月上旬,常规芋种的植株生长速度快于试管苗;武芋1号试管苗的母芋、子孙芋质量、整株质量均小于其常规芋种;试管球茎的子孙芋产量和总产量比常规芋种高,相对商品性好。对3种类型芋试管球茎产品进行比较,结果表明,试管球茎可提高多子芋、多头芋的产量,魁芋的产量则低于常规芋种;移栽大田的试管球茎苗以中苗为佳。

草地早熟禾胚性愈伤组织的诱导和植株再生体系的建立

使用MS附加2，4-D作基本培养基，对草地早熟禾进行愈伤组织的诱导和愈伤组织分化成苗试验，建立了最佳的早熟禾胚性愈伤诱导和植株再生体系．早熟禾的成熟种子经过灭菌后，接种到愈伤组织诱导培养基上，置于25±2℃，黑暗条件培养约8周-9周，有胚性愈伤组织产生．然后将愈伤组织转至分化培养基上，黑暗培养一周后，再进行光照培养，约20天后开始分化出根和芽，继续培养则长成粗壮的绿色植株．2，4-D是影响愈伤形成和植株再生的关键物质．本实验结果证明，3．0mg·L^-1和0．1mIg·L^-12，4．D是最佳浓度组合，其诱导频率和分化频率分别为67．82％和48．81％；0．5mg·L^-16-BA对根和芽的分化具有促进作用．

山梨醇延长马铃薯试管苗低温保存的效应研究

为探索山梨醇对马铃薯试管苗低温保存的影响,本研究以马铃薯品种川芋117试管苗为材料,对其在4℃低温下的保存时间、生理变化以及保存后再生植株的遗传稳定性进行了研究。结果表明:随着培养时间的延长,Ms培养基内添加20 g·L-1山梨醇,结合4℃的低温处理,能显著抑制马铃薯试管苗的株高,减缓其叶绿素和游离脯氨酸含量的下降速度;通过复壮检测,加入20 g·L-1山梨醇4℃低温保存后的马铃薯试管苗,在株高、叶数、茎粗、茎节数、根长等性状上未发现明显变异;通过RAPD技术对200条随机引物进行筛选检测,无明显的变异条带,加入20 g·L-1山梨醇4℃低温保存的马铃薯试管苗,在储存过程中未发现遗传物质改变,遗传性状可能表现相对稳定。