红薯叶片浸提液对5种主要农田杂草种子萌发及幼苗生长的化感作用

以发芽率、发芽势、根长、茎长和鲜重变化为种子萌发和幼苗生长参数,研究了作物红薯叶片水浸液对云南省农田5种恶性杂草牛膝菊、藿香蓟、鬼针草、马唐和稗草的化感作用。结果表明,红薯叶片水浸液对5种受体杂草种子发芽率的影响不明显,但对发芽势有显著抑制作用。牛膝菊、藿香蓟、鬼针草和马唐的根长和生物量随红薯叶片水浸液浓度增加而显著降低,其中对马唐的抑制最强,高浓度0.1 g/m L时对根长和生物量抑制率分别为92.04%和73.33%,而低浓度0.0125 g/m L时分别为40.99%和46.67%;其次为鬼针草、藿香蓟、牛膝菊;最差的是稗草,随浓度的变化趋势均不明显。随红薯叶片水浸液浓度增加牛膝菊、鬼针草和马唐的茎长显著地降低,其中对马唐的抑制最强,高浓度0.1 g/m L和低浓度0.0125 g/m L时分别为86.85%和70.64%;其次为鬼针草和牛膝菊;相反藿香蓟和稗草的茎长随浓度增加而显著增加,高浓度0.1 g/m L和低浓度0.0125 g/m L时对藿香蓟的促进率分别为86.97%和16.03%。红薯叶片水浸液低浓度0.0125 g/m L时对牛膝菊的茎长和生物量有促进作用(低促高抑)。从化感作用响应指数和综合效应指数的综合对比来看,红薯对牛膝菊、藿香蓟、鬼针草、马唐具有显著的化感抑制作用,随浓度增加其抑制能力显著增加;其中对马唐的为最强,其次为鬼针草、牛膝菊和藿香蓟,相反对稗草具有促进作用(除了浓度0.1 g/m L)。所有这些表明,红薯叶片水浸液对5种杂草化感作用的敏感性趋势总体为:马唐鬼针草牛膝菊藿香蓟,最不敏感或者具有促进作用的是稗草。     

Efficient embryogenic suspension culturing and rapid transformation of a range of elite genotypes of sweet potato (Ipomoea batatas [L.] Lam.)

Efficient Agrobacterium tumefaciens-mediated transformation was developed using embryogenic suspension cell cultures of elite sweet potato (Ipomoea batatas [L.] Lam.) cultivars, including Ayamurasaki, Sushu2, Sushu9, Sushu11, Wanshu1, Xushu18 and Xushu22. Embryogenic suspension cultures were established in LCP medium using embryogenic calli induced from apical or axillary buds on an induction medium containing 2 mg l⁻¹ 2,4-D. Suspension cultures were co-cultivated with A. tumefaciens strain LBA4404 harboring the binary plasmid pCAMBIA1301 with the hpt gene as a selectable marker and an intron-interrupted uidA gene as a visible marker. Several key steps of the sweet potato transformation system have been investigated and optimized, including the appropriate antibiotics and their concentrations for suppressing Agrobacterium growth and the optimal doses of hygromycin for transformant selection. A total of 485 putative transgenic plant lines were produced from the transformed calli via somatic embryogenesis and germination to plants under 10 mg l⁻¹ hygromycin and 200 mg l⁻¹ cefotaxime. PCR, GUS and Southern blot analyses of the regenerated plants showed that 92.35% of them were transgenic. The number of T-DNA insertions varied from one to three in most transgenic plant lines. Plants showed 100% survival when 308 transgenics were transferred to soil in the greenhouse and then to the field. Most of them were morphologically normal, with the production of storage roots after 3 months of cultivation in the greenhouse or fields. The development of such a robust transformation method suitable to a range of sweet potato genotypes not only provides a routine tool for genetic improvement via transgenesis but also allows us to conduct a functional verification of endogenous genes in sweet potato.     

Cryopreservation of sweetpotato (Ipomoea batatas) and its pathogen eradication by cryotherapy

Sweetpotato (Ipomoea batatas) ranks as the seventh most important staple crop in the world and the fifth in developing countries after rice, wheat, maize and cassava. Sweetpotato is mainly grown in developing countries, which account for more than 95% of total production of the whole world. Genetic resources, including cultivated varieties and wild species, are a prerequisite for novel sweetpotato breeding in both conventional and genetic engineering programs. Various cryopreservation protocols have been developed for shoot tips and embryogenic tissues. The former explants are preferred for long-term conservation of sweetpotato genetic resources, while the latter are valuable for sweetpotato genetic improvement. This review provides update comprehensive information on cryopreservation of sweetpotato shoot tips and embryogenic tissues.Plant pathogens such as viruses and phytoplasma severely hamper high yield and high quality production of sweetpotato. Thus, usage of pathogen-free planting materials is pivotal for sustainable sweetpotato production. Cryotherapy of shoot tips can efficiently eradicate sweetpotato pathogens such as viruses and phytoplasma. The mechanism behind pathogen eradication by cryotherapy of shoot tips has been elucidated. Pathogen eradication by cryotherapy provides an alternative, efficient strategy for production of pathogen-free plants. In addition, cryopreserved tissues may also be considered to be safer for exchange of germplasm between countries and regions.     

Synergistic interactions of begomoviruses with Sweet potato chlorotic stunt virus (genus Crinivirus) in sweet potato (Ipomoea batatas L.)

Three hundred and ninety‐four sweet potato accessions from Latin America and East Africa were screened by polymerase chain reaction (PCR) for the presence of begomoviruses, and 46 were found to be positive. All were symptomless in sweet potato and generated leaf curling and/or chlorosis in Ipomoea setosa. The five most divergent isolates, based on complete genome sequences, were used to study interactions with Sweet potato chlorotic stunt virus (SPCSV), known to cause synergistic diseases with other viruses. Co‐infections led to increased titres of begomoviruses and decreased titres of SPCSV in all cases, although the extent of the changes varied notably between begomovirus isolates. Symptoms of leaf curling only developed temporarily in combination with isolate StV1 and coincided with the presence of the highest begomovirus concentrations in the plant. Small interfering RNA (siRNA) sequence analysis revealed that co‐infection of SPCSV with isolate StV1 led to relatively increased siRNA targeting of the central part of the SPCSV genome and a reduction in targeting of the genomic ends, but no changes to the targeting of StV1 relative to single infection of either virus. These changes were not observed in the interaction between SPCSV and the RNA virus Sweet potato feathery mottle virus (genus Potyvirus), implying specific effects of begomoviruses on RNA silencing of SPCSV in dually infected plants. Infection in RNase3‐expressing transgenic plants showed that this protein was sufficient to mediate this synergistic interaction with DNA viruses, similar to RNA viruses, but exposed distinct effects on RNA silencing when RNase3 was expressed from its native virus, or constitutively from a transgene, despite a similar pathogenic outcome.     

Allelopathic potential of Bothriochloa laguroides var. laguroides (DC.) Herter (Poaceae: Andropogoneae)

Bothriochloa laguroides var. laguroides (DC.) Herter, a native bluestem of America, has been shown to produce many biologically active compounds. The allelopathic potential of aqueous extracts from roots, stems and leaves was examined. Lettuce seeds (Lactuca sativa) and maize (Zea mays), the common allelopathy bioassay systems, as well as seeds from two native species, wintergreen paspalum (Paspalum guenoarum) and lovegrass (Eragrostis curvula), were germinated in the presence of aqueous extracts. Percent seed germination, root and shoot elongation were measured. After 4 and 7 days root, stem and leaf extracts caused inhibition of root and shoot elongation in all four species tested. Aqueous extracts were generally less inhibitory to seed germination. Aqueous extracts from different parts of B. laguroides var. laguroides show therefore allelopathic effects inhibiting, in particular, growth of competing plants.     

云南甘薯病毒的检测及主要病毒的多样性分析

[目的]明确云南甘薯病毒的种类,并对主要病毒进行遗传多样性分析.[方法]利用PCR/RT-PCR技术,对采自云南16个县、市的279个甘薯样品进行扩增、测序,对所得序列应用分子生物学软件MEGA 5进行系统发育分析.[结果]除普洱和祥云的样品中未检测到任何病毒外,其余14个县、市的123个甘薯样品中共检测到甘薯褪绿斑病毒(SPCFV)、甘薯羽状斑驳病毒(SPFMV)、甘薯卷叶病毒(SPLCV)、甘薯C病毒(SPVC)、甘薯G病毒(SPVG)和甘薯病毒2号(SPV2)等6种病毒.其中SPVG的检出率最高,达39.1％,为云南甘薯病毒的优势种,SPFMV和SPVC的检出率分别为26.9％和24.7％,而SPLCV检出率最低,仅为0.4％.在所检测的样品中未发现甘薯褪绿矮化病毒(SPCSV)和甘薯轻斑驳病毒(SPMMV).云南甘薯病毒多数为2-5种病毒复合侵染,占总样品数的31.9％,其中2-3种病毒复合侵染现象最为常见,单一病毒侵染占总样品数的12.2％.检出率比较低的SPCFV、SPLCV和SPV2未发现单独侵染现象.[结论]云南甘薯上发生的SPFMV分离物存在EA株系和O株系,未发现RC株系,另有两个分离物同EA、O、RC之间的亲缘关系均较远,有可能是一个新的株系;SPVC和SPVG分离物均可分为3个不同的组,大部分SPVG云南分离物属于Ⅰ组.     

Optimisation of somatic embryogenesis in fourteen cultivars of sweet potato [Ipomoea batatas (L.) Lam.]

Culture procedures have been developed to facilitate the induction and maintenance of somatic embryogenic tissues in 14 out of 16 tested cultivars of sweet potato [Ipomoea batatas (L.) Lam]. Both the size of the axillary bud explant and the type of auxin were found to be critical for the successful induction of somatic embryogenesis. Of the five auxins screened 2,4-dichlorophenoxyacetic acid 2,4-D and 2,4,5-trichlorophenoxyacetic acid were the most effective, with use of the latter inducing the production of embryogenic tissues in 7 cultivars which responded poorly or not at all to 2,4-D. Procedures for secondary/cyclic embryogenesis, formation of mature embryos and their conversion to plants are also described. Received: 24 September 1996 / Revision received: 16 December 1996 / Accepted 27 January 1997     

NADPH oxidase inhibitor diphenyleneiodonium and reduced glutathione mitigate ethephon-mediated leaf senescence,H2O2 elevation and senescence-associated gene expression in sweet potato (Ipomoea batatas)

Ethephon, an ethylene releasing compound, promoted leaf senescence, H₂O₂ elevation, and senescence-associated gene expression in sweet potato. It also affected the glutathione and ascorbate levels, which in turn perturbed H₂O₂ homeostasis. The decrease of reduced glutathione and the accumulation of dehydroascorbate correlated with leaf senescence and H₂O₂ elevation at 72 h in ethephon-treated leaves. Exogenous application of reduced glutathione caused quicker and significant increase of its intracellular level and resulted in the attenuation of leaf senescence and H₂O₂ elevation. A small H₂O₂ peak produced within the first 4 h after ethephon application was also eliminated by reduced glutathione. Diphenyleneiodonium (DPI), an NADPH oxidase inhibitor, delayed leaf senescence and H₂O₂ elevation at 72 h, and its influence was effective only within the first 4 h after ethephon treatment. Ethephon-induced senescence-associated gene expression was repressed by DPI and reduced glutathione at 72 h in pretreated leaves. Leaves treated with l-buthionine sulfoximine, an endogenous glutathione synthetase inhibitor, did enhance senescence-associated gene expression, and the activation was strongly repressed by reduced glutathione. In conclusion, ethephon-mediated leaf senescence, H₂O₂ elevation and senescence-associated gene expression are all alleviated by reduced glutathione and NADPH oxidase inhibitor DPI. The speed and the amount of intracellular reduced glutathione accumulation influence its effectiveness of protection against ethephon-mediated effects. Reactive oxygen species generated from NADPH oxidase likely serves as an oxidative stress signal and participates in ethephon signaling. The possible roles of NADPH oxidase and reduced glutathione in the regulation of oxidative stress signal in ethephon are discussed.     

Heritability of regeneration in tissue cultures of sweet potato (Ipomoea batatas L.)

Summary A population of open-pollinated progeny from 12 parents, and the 12 parents, was surveyed for in vitro growth and regeneration characteristics. Four different tissue culture procedures involving different media and the use of different explants to initiate the cultures were used. Petiole explants from young leaves were used as explants for initiation of callus cultures. These were evaluated for callus growth rate, friability, and callus color and texture, before transferring to each of three different regeneration media for evaluation of morphogenetic potential. Small shoot tips also were used to initiate callus cultures, which were evaluated for the same growth characteristics and transferred to growth-regulator free regeneration media. Regeneration occurred through root or shoot regeneration or through embryogenesis. Tissue culture treatment effects, as well as genotypic effects, were highly significant in determining: the types of callus produced, callus growth rates, color and texture on the two types of media used for the second and third subcultures. The family x treatment interaction was generally not statistically significant, affecting only callus color. Estimates of narrow sense heritability for callus growth rate in both the second and third subcultures were high enough (0.35 and 0.63, respectively) for the evaluation of parental lines for selection procedures. These characteristics were also the only early culture callus traits that were consistently correlated with later morphogenesis of the cultures. They were negatively correlated with root or shoot regeneration. The occurence of somatic embryogenesis was not correlated with early callus growth characteristics. Genetic and treatment effects were highly significant in the evaluation of morphogenetic potential, through root or shoot regeneration, or through embryogenesis. Regeneration of all types was of low frequency for all procedures, expressed in 11% of the cultures of the total population.Paper No. 9906 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27695-7601, USA. From a thesis submitted by the senior in partial fulfillment of the requirements for the Ph.D. degree     

Antagonistic potential of Gluconacetobacter diazotrophicus against Fusarium oxysporum in sweet potato (Ipomea batatus)

Gluconacetobacter diazotrophicus, an endophytic diazotroph also encountered as rhizosphere bacterium, is reported to possess different plant growth promoting characteristics. In this study, we assessed the biocontrol potential of G. diazotrophicus under in vitro conditions with soil-borne plant pathogenic Fusarium oxysporum. The possible compounds involved in the biocontrol involves 2,4-diacetylphloroglucinol, Pyrrolnitrin and Pyoluteorin. Thin layer chromatography analysis revealed that G. diazotrophicus produced the antibiotic, Pyoluteorin which helped in the suppression of soil-borne pathogenic. The volatile compounds of G. diazotrophicus also inhibited the growth of F. oxysporum. Tests for the production of hydrogen cyanide indicated that G. diazotrophicus does not produced HCN.     

Bone and faecal minerals and scanning electron microscopic assessments of femur in rats fed phytic acid extract from sweet potato (<Emphasis Type="Italic">Ipomoea batatas</Emphasis>)

Phytic acid was extracted from sweet potato (Ipomoea batatas) and fed to Wistar rats with or without zinc for 3 weeks. Animals were then sacrificed and bone and faecal minerals were assessed. The ultra-structure of the bones was examined via scanning electron microscopy. Phytic acid extract or commercial phytic acid supplemented diets (D + Zn + PE or D + PE) displayed reduced bone calcium levels (101.27 ± 59.11 and 119.27 ± 45.36 g/kg) compared to the other test groups. Similarly, reduced calcium were observed in the control groups (D + Zn and D) fed formulated diets with or without zinc supplementation (213.14 ± 15.31 and 210 ± 6.88 g/kg) compared to the other test groups. The group fed supplemented commercial phytic acid diet (D + CP) demonstrated the lowest femur magnesium (3.72 ± 0.13 g/kg) while the group fed phytic acid extract supplementation (D + PE) recorded the highest level (4.84 ± 0.26 g/kg) amongst the groups. Femur iron was highest in the group fed commercial phytic acid supplemented diet (D + CP −115.74 ± 2.41 g/kg) compared to the other groups. Faecal magnesium levels were significantly higher in the two test groups fed phytic acid extract with or without zinc (D + Zn + PE or D + PE) compared to all other groups. All the groups which had phytic acid supplemented diets had significantly thinner bone in the trabecular region, compared to the groups fed formulated diet or zinc supplemented formulated diet (D or D + Zn). These observations suggest that the consumption of foods high in phytic acid may contribute to a reduction in the minerals available for essential metabolic processes in rats.     

Application of simultaneous saccharification and fermentation (SSF) from viscosity reducing of raw sweet potato for bioethanol production at laboratory, pilot and industrial scales

The aim of this work was to research a bioprocess for bioethanol production from raw sweet potato by Saccharomyces cerevisiae at laboratory, pilot and industrial scales. The fermentation mode, inoculum size and pressure from different gases were determined in laboratory. The maximum ethanol concentration, average ethanol productivity rate and yield of ethanol after fermentation in laboratory scale (128.51 g/L, 4.76 g/L/h and 91.4%) were satisfactory with small decrease at pilot scale (109.06 g/L, 4.89 g/L/h and 91.24%) and industrial scale (97.94 g/L, 4.19 g/L/h and 91.27%). When scaled up, the viscosity caused resistance to fermentation parameters, 1.56 AUG/g (sweet potato mash) of xylanase decreased the viscosity from approximately 30000 to 500 cp. Overall, sweet potato is a attractive feedstock for be bioethanol production from both the economic standpoints and environmentally friendly.     

Isolation and characterization of some proteolytic enzyme inhibitors in sweet potato (Ipomoea batatas)

Ten trypsin (EC 3.4.21.4) inhibitors have been isolated and purified by gel filtration and ion-exchange chromatography from the tubers of sweet potato (Ipomoea batatas). The molecular weights of the three most active inhibitors were estimated by molecular sieve chromatography and found to be 12 000, 10 000 and 9300, respectively. They showed maximum activity at pH 7.5–8.5 as well as maximum K_i within this pH range. They displayed different trypsin inhibitory activity, and this activity was completely lost on boiling for 40 min.     

Cryopreservation of shoot tips from in vitro plants of sweet potato [Ipomoea batatas (L.) Lam.] by vitrification

 Routine cryopreservation of shoot tips from sweet potato [Ipomoea batatas (L.) Lam] has been hampered by their survival variability after cryogenic exposure. We examined the effects of light conditions on stock plants, sucrose preculture and cryoprotectant loading on survival after vitrification using PVS2 solution. The survival of vitrified sweet potato shoot tips cooled to approximately –208  °C was increased by preculturing with 0.3 M sucrose for 24 h at 22  °C. Survival was also enhanced by excising shoot tips immediately after the 8-h dark photoperiod. The best survival after cryogenic exposure was obtained using 2 M glycerol +0.4 M sucrose for 1 h at 22  °C followed by dehydration with PVS2 for 16 min at 22  °C. Rapid cooling was used and achieved by the immersion of foil strips into partially solidified nitrogen. Successfully vitrified and warmed shoot tips directly developed shoots on a medium containing 1 μM NAA, 0.5 μM BA and 0.1 μM kinetin with only minimum callus formation. Shoot formation occurred in all surviving shoot tips. This procedure shows promise for cryopreserving sweet potato shoot tips. Received: 2 March 1999 / Revision received: 21 September 1999 / Accepted: 29 September 1999     

Involvement of nitrogen in storage root growth and related gene expression in sweet potato (Ipomoea batatas)

• Nitrogen (N) could affect storage root growth and development of sweet potato. To manage external N concentration fluctuations, plants have developed a wide range of strategies, such as growth changes and gene expression.
• Five sweet potato cultivars were used to analyse the functions of N in regulating storage root growth. Growth responses and physiological indicators were measured to determine the physiological changes regulated by different N concentrations. Expression profiles of related genes were analysed via microarray hybridization data and qRT‐PCR analysis to reveal the molecular mechanisms of storage root growth regulated by different N concentrations.
• The growth responses and physiological indicators of the five cultivars were changed by N concentration. The root fresh weight of two of the sweet potato cultivars, SS19 and GS87, was higher under low N concentrations compared with the other cultivars. SS19 and GS87 were found to be having greater tolerance to low N concentration. The expression of N metabolism and storage root growth related genes was regulated by N concentration in sweet potato.
• These results reveal that N significantly regulated storage root growth. SS19 and GS87 were more tolerant to low N concentration and produced greater storage root yield (at 30 days). Furthermore, several N response genes were involved in both N metabolism and storage root growth.

     

云南省气候生产潜力的时空变化

利用云南省1961-2017年101个国家级气象站年平均气温、年降水量资料,运用Miami模型、Thornthwaite Memorial模型计算了云南省3种气候生产潜力,用Mann-Kendell法进行突变检验,并分析了时空分布特征及未来趋势.结果表明:研究期间,云南平均温度气候生产潜力(Yt)、降水气候生产潜力(Yr)和蒸散气候生产潜力(Ye)值分别为1968、1477、1434 g·m^-2·a^-1,Yt呈波动上升状态,Yr/Yt值显示地区间水热配比差异大,约束性条件也明显不同;气候生产潜力存在突变现象,Yt在2001年开始明显突变,Yr没有突变,Ye在2002-2004年有突变;气候生产潜力及气候倾向性空间分布不均,全省各地年平均Yt、Yr和Ye分别在1030~2465、927~2341和832~1995 g·m^-2·a^-1,3种气候生产潜力均为滇西北和滇东北最低,滇西南和滇南最高,大部分地区Yt、Yr和Ye的气候倾向率分别为增长、减小和增长趋势;8种模拟未来气候变化的方案(仅气温增加1℃、仅降水增加10%、仅气温降低1℃、仅降水减少10%、气温增加1℃且降水减少10%、气温增加1℃且降水增加10%、气温降低1℃且降水增加10%、气温降低1℃且降水减少10%)将导致研究区Ye分别变化6~45、13~77.2、15~67、-87^-17、-74~46、58~96、-54~57、-101^-59 g·m^-2·a^-1.整体上,如果未来气候趋于"暖湿"化,将有利于研究区农作物增产,如果趋于"冷干"化,将不利于农作物生产.     

Metabolism of ipomeamarone in sweet potato root slices before and after treatment with mercuric chloride or infection with Ceratocystis fimbriata

Furanoterpenes produced in sweet potato (Ipomoea batatas) root tissue in response to fungal infection or injury with mercuric chloride were metabolized to compounds negative to Ehrlich's reagent. The metabolism of ipomeamarone in sweet potato root tissue was enhanced in response to cut injury. The enhanced metabolism of ipomeamarone in the cut tissue was partly prevented by HgCl₂ treatment. The initial metabolite of ipomeamarone was identified as ipomeamaronol, 15-hydroxyipomeamarone. A time-course analysis of the metabolism of [¹⁴C]ipomeamarone by cut tissue indicated that ipomeamarone was converted to ipomeamaronol, which was further metabolized to unknown compounds.