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.

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.

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.

番禺果蔗宿根矮化病调查及分析

为明确广州市番禺果蔗主产区甘蔗宿根矮化病的发生情况,利用PCR技术,对随机采自番禺区农户和本所试验地120个果蔗样品进行检测。结果表明:黑皮果蔗的RSD检出率为93%,黄皮果蔗的RSD检出率为95%,果蔗健康种苗的RSD检出率为0%。果蔗健康种苗有效的去除了甘蔗宿根矮化病,推广果蔗健康种苗可促进果蔗产业健康发展。

果蔗脱毒与常规种茎苗生产性状比较

通过对果蔗相关性状的测定,分析果蔗脱毒种茎苗与常规种茎苗(CK)生产性状之间的差异。结果表明,除出苗率、出苗速度外,果蔗脱毒种茎苗在月生长速度、株高、节间长度、蔗茎产量和蔗糖、还原糖、氨基酸含量方面与常规种茎苗(CK)相比,差异都达到显著或极显著水平,其中蔗茎产量比常规种茎苗(CK)增产21.75%,蔗糖含量比常规种茎苗(CK)提高1.10个百分点,表现出较好的生产性状,在生产上具有一定的推广前景。

槽轮式甘蔗健康种苗种植机的设计与试验检测

甘蔗健康种苗种植技术是提高甘蔗单产水平和品质、节约下种量降低生产成本的主要技术措施之一,我国甘蔗生产机械化程度低,国内现有甘蔗种植机主要为传统双芽段式,存在耗费人工多、作业效率低、作业质量不稳定、耗种量大、与单芽段的甘蔗健康种苗不兼容等问题,直接限制了这项技术的推广和应用。国外全自动甘蔗种植机多为整杆和双芽段式,结构复杂造价高、与国内种植农艺不配套导致无法引进应用。针对上述问题,基于甘蔗健康种苗单芽段的物理特性,设计了一种液压槽轮式甘蔗健康种苗种植机,利用Solid Edge ST5三维软件建模,对关键部件进行力学有限元分析,检验机构合理性,加工样机进行田间试验检测,结果表明比传统双芽段实时斩种式种植机生产率提高30%,下种量节约66%,人工劳动强度降低50%,验证了该槽轮式甘蔗健康种苗种植机设计方案的可行性。

黑皮果蔗茎尖脱毒不同代数种茎苗商品性能研究

以黑皮果蔗茎尖脱毒第1代(处理A)、第2代(处理B)、第3代(处理C)种茎为材料,研究其商品性能生产表现情况。结果表明,脱毒果蔗不同代数种苗的月生长速度、株高、茎径、蔗茎产量与对照相比差异性均达极显著水平,其中,蔗株最高、茎径最粗、蔗茎产量最高等均为第2代种茎苗,分别比对照高41cm、粗0.25cm、增产41.1%;在品质方面,脱毒果蔗的水分含量较高,纤维分含量较低,糖分略低于对照;在外观品质方面,脱毒果蔗的节间长度、均匀度、色泽等均优于对照,由花叶病引起的花皮蔗株低于对照;脱毒果蔗易受外界花叶病毒的传染,随种植年限的增加,花叶病发病率提高;脱毒果蔗叶片的叶绿素含量、ATP酶活性提高;第1代种茎苗可栽培成商品蔗,但存在一定的组培效应,主要表现为蔗茎的侧芽较大,在光线条件较好的地方较易萌动。

几个甘蔗新品种的健康种苗对比试验

为探讨甘蔗新品种健康种苗的应用效应,对6个甘蔗新品种进行了为期两年的健康种苗对比试验。结果表明:(1)健康种苗可显著增加甘蔗产量和含糖量,这种效应可从新植蔗延续至宿根蔗且因品种而异。健康种苗甘蔗产量增产16.4%,含糖量增产15.9%。(2)健康种苗对甘蔗蔗糖分无显著作用。(3)健康种苗对甘蔗产量性状作用是多方面的,可促进甘蔗发芽出苗,增加分蘖、株高、茎径和有效茎数。该试验结果对健康种苗在甘蔗生产上的应用具有一定的指导作用。

甘蔗健康种苗田间评价试验结果分析

甘蔗宿根矮化病(Ratoon Stunting Disease,RSD)是一种世界性的危害性较严重的甘蔗病害,其较有效的防治方法是种植健康种苗。为了评价甘蔗健康种苗的田间效果,本文进行了粤糖00-236健康种苗与其普通种茎苗新植田间比较试验,并应用斑点酶链免疫试验(Dot Blot Enzymelinked Immuno Assay,DB-EIA)对种苗RSD病菌进行检测,结果表明:粤糖00-236健康种苗较其普通种茎苗蔗茎产量增产10.6%(达显著水平,小区试验)和9.1%(大面积示范),甘蔗蔗糖分提高0.26个百分点,且萌芽快,萌芽率较普通种茎苗提高22.94个百分点(达显著水平),粤糖00-236健康种苗的公顷有效茎数达11400条(达极显著水平),分蘖率高3.0个百分点,但两者的茎径、生长速及茎长差异不明显。表明粤糖00-236新植健康种苗具有显著的增产效果,蔗糖分也略有提高。

甘蔗脱毒健康种苗宿根矮化病的PCR检测

[目的]为甘蔗脱毒健康种苗宿根矮化病的检测提供好的方法。[方法]利用PCR技术对甘蔗脱毒健康种苗进行甘蔗宿根矮化病(RSD)病菌的检测研究。[结果]在甘蔗健康种苗生长的前几个不同时期(组培苗增殖、生根、丛苗沙培和单株假植阶段),甘蔗宿根矮化病菌的检测结果均为阴性。对PCR检测灵敏度的研究表明,PCR能够检测到甘蔗宿根矮化病菌液浓度10-3。[结论]PCR检测特异性好、灵敏度高,适合甘蔗脱毒健康种苗生产中的大批量检测。

不同甘蔗品种单芽段种茎生产性能分析

探讨不同甘蔗品种单芽段种茎在生产应用中的产量潜能,为甘蔗精量和高效率种植技术推广及应用提供科学依据。在宾阳县邹圩镇甘蔗“双高”基地,设置桂糖42号单芽段(A1)、桂糖42号双芽段(A2)、桂糖44号单芽段(B1)、桂糖44号双芽段(B2)、桂糖49号单芽段(C1)、桂糖49号双芽段(C2)、桂糖55号单芽段(D1)和桂糖55号双芽段(D2)共8个处理,分别调查新植蔗和宿根蔗的农艺、产量及品质性状。结果表明:甘蔗单芽段种茎处理的新植蔗在出苗率、分蘖发生率、分蘖率和单位面积有效茎数上表现出高于双芽段种茎处理,均达到0.01极显著差异水平,且在桂糖44号中表现最为明显,分别提高20.30%、17.74%、58.26%、15.49%;在宿根蔗表现上,单芽段种茎处理的发株数、发株率、单位面积有效茎数、产量和产糖量高于双芽段种茎处理,桂糖44号单芽段种茎处理的宿根蔗比双芽段种茎处理分别提高15865株/hm2、12.64%、15.39%、13.59%、13.12%。本试验研究结果为甘蔗单芽段种茎技术在生产中推广应用提供科学参考。

甘蔗白叶病抗病性鉴定方法的建立与应用

为建立简便高效、致病性稳定和规范实用的甘蔗抗白叶病鉴定方法,推动甘蔗抗白叶病育种,本文从甘蔗材料处理与种植、接种液配制、接种方式、病情调查、分级标准制定等层面对甘蔗抗白叶病鉴定技术进行了系统研究与探索,首次优化创建了简便高效、致病性稳定和规范实用的甘蔗抗白叶病鉴定方法,即种苗喷雾接种法和生长期切茎接种法。种苗喷雾接种法:直接筛选甘蔗白叶病植原体蔗茎榨汁加10倍量无菌水配制接种液,接种液喷洒蔗种,塑料薄膜保湿,接种材料桶栽置于防虫温室培养,接种种植30 d开始调查病株率,按1~5级标准进行抗病性评价。切茎接种法:直接筛选甘蔗白叶病植原体蔗茎榨汁加10倍量无菌水配制接种液,鉴定材料桶栽置于防虫温室培养,株龄6月时切茎用移液枪将100μL接种液滴入根部切口接种,接种种植20 d开始调查病株率,按1~5级标准进行抗病性评价。两种方法与自然传播相似,接种后发病显著、灵敏度高、重现性好,抗性鉴定结果与田间自然发病相吻合。通过两种接种方法和田间自然发病调查,鉴定明确了10个主栽品种对甘蔗白叶病抗病性,其抗病性真实、可靠,可作为今后甘蔗抗白叶病鉴定标准品种。

外源赤霉素信号对甘蔗分蘖及其内源激素的影响

前期研究发现,外源GA信号影响了甘蔗分蘖进程。为了解GA信号对甘蔗不同分蘖时期叶片内源激素含量的影响,以综合性状优良的甘蔗主栽品种‘桂糖42号’为材料,采用不同外源GA信号调节剂对蔗种进行浸种处理,并以清水处理为对照(CK),分别测定分蘖初期、盛期和末期+1叶(主苗+分蘖苗)中内源激素吲哚乙酸(indole-3-acetic acid,IAA)、赤霉素(gibberellins,GA)、乙烯(ethylene,ETH)、细胞分裂素(cytokinin,CTK)、脱落酸(abscisic acid,ABA)和油菜素内脂(brassinosteroids, BR)的含量,并分析它们之间的相关关系。结果表明:外源GA_(3)(gibberellic acid3;GA生物合成促进剂)对蔗种浸种处理后,增加了分蘖期甘蔗分蘖叶片中IAA、GA和CTK的总体含量,提高了分蘖前期ETH含量和后期ABA含量;多效唑(paclobutracol,PP_(333);GA生物合成抑制剂)处理后却增加了分蘖前期内源GA和ABA含量,提高了后期分蘖叶片中ETH含量,同时降低了CTK和BR含量。进一步的相关性分析发现,利用外源赤霉素信号促进剂处理蔗种后,甘蔗叶片内源激素IAA与GA、CTK和BR、CTK与GA均呈显著正相关;而ABA与GA呈显著负相关,与ETH呈显著正相关。可见,外源GA信号影响了甘蔗分蘖期叶片内源激素系统,促进生长的激素与抑制生长的激素达到动态平衡状态,最终导致了甘蔗分蘖的差异。甘蔗分蘖与植物内源激素含量密切相关,可通过施用外源激素来影响内源激素的含量,调控激素之间的动态平衡,达到提高甘蔗分蘖形成及其成茎的目的。

STABILITY ANALYSIS OF A COMPUTER VIRUS PROPAGATION MODEL WITH ANTIDOTE IN VULNERABLE SYSTEM

We study a proposed model describing the propagation of computer virus in the network with antidote in vulnerable system. Mathematical analysis shows that dynamics of the spread of computer viruses is determined by the threshold Ro. If Ro 〈 1, the virusfree equilibrium is globally asymptotically stable, and if R0 〉 1, the endemic equilibrium is globally asymptotically stable. Lyapunov functional method as well as geometric approach are used for proving the global stability of equilibria. A numerical investigation is carried out to confirm the analytical results. Through parameter analysis, some effective strategies for eliminating viruses are suggested.

甘蔗脱毒健康种苗田间比较试验

甘蔗脱毒健康种苗与常规种植田间比较试验结果表明,在新植连作时,无论是否健康种苗繁殖的后代,每茬都进行热水脱毒处理,其效果好于传统的常规种植,桂糖11号蔗茎增幅45.28%～51.19%,拔地拉蔗茎增幅61.49%～66.22%;而且每茬下种前的种茎都进行热水处理后种植比前茬健康种苗种植出的种茎不再进行热水处理就直接下种效果好,桂糖11号蔗茎增幅2.92%～6.78%,拔地拉蔗茎增幅0.48%～0.66%;而后者又比传统常规种植方法好,桂糖11号蔗茎增幅38.50%～48.27%,拔地拉蔗茎增幅61.01%～65.56%。上一茬已做过热水处理、茎尖脱毒组培苗种植,新植1年后的宿根蔗桂糖11号蔗茎增幅也比对照高32.05%～40.86%。各个处理的蔗糖分均比对照有所提高,增幅0.91%～1.71%(绝对值)。