现代生物技术在甘薯育种中的应用

现代生物技术攻克了过去在甘薯(Ipomoea batatas)育种中无法解决的难题。诱变育种、细胞工程、分子标记和基因工程等现代生物技术已在甘薯选育、品质改良、增强抗病虫性等方面上发挥了非常重要的作用。综述了诱变育种、细胞工程、分子标记和基因工程等现代生物技术在甘薯育种中的研究与利用概况。     

紫甘薯花色苷的组分及抗氧化活性研究(英文)

对紫甘薯花色苷的化学成分和抗氧化活性进行了研究.研究采用大孔树脂AB-8纯化紫甘薯花色苷,高效液相色谱-2极管阵列法(HPLC-DAD)分析表明,纯化后的提取物中共含有11种花色苷,其中主要成分为酰化的矢车菊素和芍药素.并测定了紫甘薯总花色苷在DPPH自由基清除体系、超氧阴离子体系、还原力和亚油酸体系的抗氧化活性.在质量浓度均为0.5g/L时,花色苷、L-AA和 BHT的还原力分别为0.572、0.460 和0.121,花色苷的清除DPPH自由基的半数抑制浓度(IC50)和清除超氧阴离子IC50分别为6.94和3.68mg/L,表明花色苷还原能力强,并能有效地清除DPPH自由基和超氧阴离子.此外,紫甘薯花色苷能较好地抑制脂质过氧化.     

30个中国甘薯主栽品种的RAPD指纹图谱构建及遗传变异分析

研究以中国30个甘薯主栽品种为材料,对甘薯RAPD指纹图谱的构建进行了探讨。从102个RAPD引物中筛选出26个多态性丰富的引物用于PCR扩增,共扩增出255条多态性条带,平均每个引物扩增的多态性带数为9.8条。其中S32和S39多态性最高,仅用其中1个引物即能将这30个甘薯品种完全区分开,且由此构建的指纹图谱出现的概率很小,分别为4.77×10^-7（1/221）和1.91×10^-6（1/219）。结果进一步表明,这30个甘薯品种的遗传距离变异幅度较大,为0.0390～0.4306,平均遗传距离为0.3086。RAPD聚类分析表明,地域分布相近的甘薯品种和具有同一亲本的甘薯品种聚在一起,与这些甘薯品种的系谱图一致。     

紫色甘薯营养成分和药用价值研究进展

紫色甘薯[Ipomoea batatas（L.）Lam.]是一种富含天然食用色素的独特甘薯。从20世纪90年代初在日本农林水产省九州农业试验场选育出的“川山紫”开始,紫色甘薯由于富含多种营养成分,具有清除自由基抗氧化、预防和治疗心血管疾病等多种药用功能而在日本等发达国家得到广泛推广。就国内外对紫色甘薯各方面的研究,对其营养成分和药用价值进行论述,为在国内广泛推广种植紫色甘薯新品种提供重要依据。     

4QL―1型甘薯起垄收获多功能机的设计与试验

设计了一款可实现甘薯施肥、起垄、镇压和收获作业的起垄收获多功能机,并阐述了整机和关键部件结构设计、工作原理及技术参数。在粘重土壤区试验考核表明,该机性能稳定,作业顺畅,起垄主要指标为:土垄垄形一致性为97%,土壤容重变化率为27%,邻接垄垄距合格率为90%;收获主要指标为:明薯率为97%,漏挖率为0.3%,伤薯率为1%,破皮率为1.5%。     

Efficient elimination of sweetpotato little leaf phytoplasma from sweetpotato by cryotherapy of shoot tips

Shoot tips with 3–4 leaf primordia were excised from in vitro -grown sweetpotato plants ( Ipomoea batatas ) infected with little leaf phytoplasma ( Candidatus Phytoplasma aurantifolia) and subjected to cryotherapy. All plants regenerated from the cryo-treated shoot tips were free of phytoplasma, whereas shoot tip culture or dehydration of shoot tips without subsequent cryotherapy resulted in phytoplasma-free plants at a frequency of only 7–10%. Histological and ultrastructural studies with light and transmission electron microscopy, respectively, indicated that cryotherapy was lethal to all cells except those in the apical dome of the meristem and the two youngest leaf primordia. These surviving parts of the shoot tip contained vascular tissue and sieve elements, but electron microscopy showed no phytoplasma in them. In contrast, an abundance of phytoplasma was found in sieve elements located at the lower, non-surviving parts of the shoot tip 1·0 or 1·5 mm from the apical dome. In the greenhouse, the plants in which phytoplasmas were not detected were healthy-looking, grew vigorously and were readily distinguished from the infected plants that exhibited little leaf and chlorosis symptoms, proliferation of axillary shoots and roots, stunting, and heavily reduced number and size of storage roots. In this study efficient elimination of phytoplasma and production of pathogen-tested plant stocks were achieved with the novel cryotherapy-based approach. The proposed advantage of the technique is that it can be simultaneously used for long-term storage of plant germplasm and for production of pathogen-free plants.     

Cloning and Characterization of a Salt Tolerance-Associated Gene Encoding Trehalose-6-Phosphate Synthase in Sweetpotato

Trehalose plays an important role in metabolic regulation and abiotic stress tolerance in a variety of organisms. In plants, its biosynthesis is catalyzed by two key enzymes： trehalose-6-phosphate synthase（TPS） and trehalose-6-phosphate phosphatase（TPP）. In the present study, a TPS gene, named IbTPS, was first isolated from sweetpotato（Ipomoea batatas（L.） Lam.） cv. Lushu 3 by rapid amplification of cDNA ends（RACE）. The open reading frame（ORF） contained 2 580 nucleotides encoding 859 amino acids with a molecular weight of 97.433 kDa and an isoelectric point（pI） of 5.7. The deduced amino acid sequence showed high identities with TPS of other plants. Real-time quantitative PCR analysis revealed that the expression level of IbTPS gene was significantly higher in stems of Lushu 3 than in its leaves and roots. Subcellular localization analysis in onion epidermal cells indicated that IbTPS gene was located in the nucleus. Transgenic tobacco（cv. Wisconsin 38） plants over-expressing IbTPS gene exhibited significantly higher salt tolerance compared with the control plant. Trehalose and proline content was found to be significantly more accumulated in transgenic tobacco plants than in the wild-type and several stress tolerance related genes were up-regulated. These results suggest that IbTPS gene may enhance salt tolerance of plants by increasing the amount of treahalose and proline and regulating the expression of stress tolerance related genes.     

厚藤种子萌发特性

以厚藤Ipomoea pes-caprae种子为试验材料,测定其种子的大小、千粒质量、硬实率、生活力以及在不同处理条件下的发芽势和发芽率。结果表明:机械处理下的效果最好,其种子平均发芽势和发芽率均提高到95.3%;其次为980 gkg－1硫酸处理90 min较好,平均发芽势达到91.2%,发芽率达93.5%;氢氧化钠处理也可明显提高厚藤种子萌发能力,400 gkg－1氢氧化钠处理36 h的平均发芽率可达79.4%;不同温度处理以25 ~ 30 ℃的萌发能力最强,其发芽势为24.6%,发芽率为43.4%。实际工作中,可以采用机械处理或酸碱处理的方法以提高厚藤种子的萌发能力。图2表4参18     

Influence of different forage grasses on nitrate capture and leaching loss from a pumice soil

Nitrogen (N) uptake and loss in leachate from a pulse of ¹⁵N-labelled synthetic cow urine applied to a pumice soil were compared in a glasshouse lysimeter experiment among the grass species, Agrostis capillaris , Dactylis glomerata , Phalaris aquatica , Lolium multiflorum , L . perenne and a L . multiflorum/A. capillaris mixture. In addition, four L. perenne treatments investigated the effect of infection by Neotyphodium lolii strains. Leachate volumes and leachate nitrate concentrations were measured. At final harvest 24 weeks after sowing, dry matter (DM) mass of shoots and roots, plant N and ¹⁵N contents, soil residual mineral N, and root diameters and lengths were measured. Endophyte had no effect on plant or nitrate variables. Lysimeters planted with L . perenne (pooled endophyte treatments) leached 48 mg of NO₃-N compared with <3 mg N for the other grasses. Recovery of ¹⁵N was highest in A. capillaris (0·99), followed by D. glomerata and P. aquatica (0·89), the L . multiflorum / A. capillaris mixture (0·87), L . multiflorum (0·60) and L . perenne (0·44). Low ¹⁵N recoveries and high leaching losses from L . perenne were associated with low plant and root masses of DM and low rooting depth. High aerial mass of DM, root systems extending below 20 cm and high root masses of DM in lysimeters with A. capillaris , P. aquatica and D. glomerata contributed to a high rate of nitrate interception by these species and low leachate losses. The L . multifloru m/ A. capillaris mixture was intermediate between the two species for most of the variables measured.     

Sweetpotato viruses in China

China is the largest sweetpotato producer country in the world, with its total growing area and yield reaching 5.5 million ha and 106 million metric tones, respectively. Viral diseases constitute a major hindrance to the development and highly profitable production of the sweetpotato industry. The present article provides updated comprehensive information on type of virus, yield loss caused by viruses, increased yield and benefits by cultivation of virus-free plants. By analyzing data on changes in vegetative growth and physiology of plants infected by viruses, the authors attempted to elucidate the mechanisms by which infection of viruses caused significant losses of the root tuber yield. Meristem culture techniques for production of virus-free sweetpotato plants and propagation system of virus-free seed tubers have been well developed in China. At present time, virus-free sweetpotato seed tubers have been widely used in major sweetpotato-growing areas in China. Usage of virus-free seed tubers has brought great benefits to the sweetpotato industry in China.