Development of SRAP Markers Linked to a Gene for Stem Nematode Resistance in Sweetpotato, Ipomoea batatas (L.) Lam.

Sequence-related amplification polymorphism （SRAP） markers closely linked to stem nematode resistance gene were developed in sweetpotato, lpomoea batatas （L.） Lam. Using bulked segregant analysis （BSA）, 200 SRAP primer combinations were screened with the resistant and susceptible bulked DNA from the 196 progenies of an F1 single-cross population of resistant parent Xu 781xsusceptible parent Xushu 18, 77 of them showed polymorphic bands between resistant and susceptible DNA. Primer combinations detecting polymorphism between the two bulks were used to screen both parents and 10 individuals from each of the bulks. The results showed that primer combination A9B4 produced 3 specific bands in the resistant plants but not in the susceptible plants, suggesting that the markers, named Nspl, Nsp2 and Nsp3, respectively, linked to a gene for stem nematode resistance. Primer combination A3B6 also produced a SRAP marker named Nsp4 linking to the resistance gene. Amplified analysis of the 196 F1 individuals indicated that the genetic distance between these markers and the resistance gene was 4.7, 4.7, 6.3, and 9.6 cM, respectively.

Influence of Sanitization Process on Maintaining Sweet Potato Quality for Export

The whole cold-chain for exporting sweet potato(native variety“Abees”),to foreign market included immediate curing operation directly after harvest helped in healing skin texture,however,in order to reduce postharvest soft rot(Rhizopus stolonifer)incidence following trimming,and washing,ultraviolet light(UV-C)treatment was used as a main sanitizer for eliminating the soft rot.Exposure of the roots to UV-C(254 nm)was applied in a UV-C room on freshly harvested and cured sweet potato while rolling up on a movable line at 20 cm distance for 1,2,and 3 hr.As combining UV-C treatment with chlorine(200 ppm)on roots,marked and significant reduction of the total microbial load and Rhizopus potential was achieved on root surfaces respectively compared with chlorine alone.It also reduced soft rot percentage to almost 0%infection.After 3 months of cold-storage,quality assessment of sweet potato showed that root characteristics were markedly maintained.The ability of UV-C light to induce phenylalanine ammonia lyase(PAL)enzyme activity in root tissue and maintain the activities of peroxidase and polyphenol oxidase,however with slight increase,was detected.UV-C caused an increase of phenol content in sweet potato tissue that made an activation of defense reaction against the rot causal pathogen.As the exposure time to UV-C light increased,a higher content of phenols occurred.Moreover,UV-C application caused decrease in sugar content of root tissue that is flavored by soft rot-causal pathogen.

Identification and Quantification of Allelochemicals from Selected Sweet Potato (<i>Ipomoea batatas</i>(L.) Lam.) Cultivars

Allelopathic compounds have the potential to inhibit the growth and development of other organisms in a diverse manner ranging from shifting nutrients and enhancing their growth to inflicting diseases. In addition, these compounds influence seedling growth and seed germination of various crops. The goal of this study was to identify and quantify different allelochemicals in various sweet potato cultivars through high-performance liquid chromatography techniques. Selected sweet potato slips (weight: 2.0 - 2.5 grams/slip) were propagated in separate glass tubes filled with 10.0 mL distilled water. Water extract from each glass tube was collected after 2, 4, and 6 weeks after transplanting (WAP) to identify and quantify allelochemical compounds by comparing their peaks with the retention time of standards. Results show that the concentration of allelochemicals in water extract was increased from 2 to 4 WAP but remained constant in the sixth week. Quantitative analysis revealed that the amount of chlorogenic acid was higher in all sweet potato cultivars compared to other allelochemicals. Some sweet potato cultivars, A5 and A39, exhibited higher allelopathy (18.28 - 19.37 ppm/slip) and reduced the height and biomass of Palmer amaranth the most due to the presence of increased concentration of combined allelochemicals, while other cultivars produced lesser allelochemicals (10.90 ppm/slip) and did not reduce the growth of the weed species. Allelopathic sweet potato cultivars high in chlorogenic acid production can effectively suppress Palmer amaranth with minimal dependence on chemicals to manage weeds and harmful pests under sustainable agricultural system.

Regulation of Anthocyanin during Storage Root Development Stage in Sweet Potato(Ipomoea batatas(L.) Lam.)

Anthocyanin accumulation during storage root development in purple-fleshed sweet potato was analyzed by detection of anthocyanin concentration, accumulation rate and the expression pattern of anthocyanin biosynthetic genes by semi-quantitative RT-PCR. Anthocyanin concentration in sweet potato cvs Jishu 18 and Ayamurasaki increased steadily during storage root development stage. The accumulation rate in two genotypes peaked at 50 to 65 d after transplanting, and then declined rapidly. During storage root development of Ayamurasaki, the anthocyanin biosynthesis gene, IbCHS, was constitutively expressed, the genes IbF3H, IbDFR, IbANS were induced steadily, reaching a maximum at the later stage of root thickening, and IbPAL steadily decreased. Therefore, the mechanism of anthocyanin accumulation differed between the two cultivars, and anthocyanin biosynthesis was regulated through regulation of its synthetic enzymes.

Comparison of Physicochemical,Organoleptic and Nutritional Abilities of Eight Sweet Potato(Ipomoea batatas)Varieties

In Martinique (F.W.I.), biodiversity of vegetable varieties remain unexploited due to public unawareness or supply problems. To further enhance the sweet potato, physicochemical, sensory and nutritional characteristics of eight varieties of sweet potato were established. The eight sweet potatoes cultivars were noticeably diverse with phenotypic, sensory, physicochemical and nutritional characteristics which were very varied. The eight cultivars grown in Martinique were advantageously positioned in relation to the globally identified sweet potato, regarding fibre, starch, potassium, copper, vitamin B1, B3 and B9 contents. Compared to the ordinary potato, Martiniquan sweet potatoes have a much better nutritional potential. Energy value and vitamin C levels were twice as much as in normal potatoes. Martiniquan sweet potatoes cultivars were also richer in minerals and vitamins, with 2.7 times more vitamin B9 and 63 times more beta-carotene than the ordinary potato.

甘薯(Ipomoea batatas(L.)lam)不定根根尖细微结构的初步研究

顶端分生组织细胞有高的核质比，胞质中可见前质体和其它细胞器．分化的组织原细胞中，皮层原细胞较中柱原和根冠表皮原细胞内前质体增多明显．组织原细胞内的前质体均匀散布高电子密度基质，并以溢痕方式分裂．淀粉颗粒最先出现在分化早期的皮层细胞和根冠表皮细胞中．较大液泡形成先见于根冠表皮细胞原和中柱内的分化早期细胞．外皮层细胞弦向壁纤维化增厚，径向壁薄，具凯氏带结构．提示甘薯不定根尖早期的外皮层细胞可以分化为既具支持保护作用也适应代谢转运功能的单位．

甘薯(Ipomoea batatas(L.) Lam.)试管苗种质保存技术研究进展

甘薯种质资源的大田种植保存面临着严重的病毒感染以及病虫害、自然灾害的影响。由茎尖分生组织培养成无病毒苗并进行试管保存,是当前既经济又实用的方法。

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.

Molecular Cloning and Functional Characterization of a Salt Tolerance-Associated Gene IbNFU1 from Sweetpotato

Iron-sulfur cluster biosynthesis involving the nitrogen fixation（Nif） proteins has been proposed as a general mechanism acting in various organisms.NifU-like protein may play an important role in protecting plants against abiotic and biotic stresses.Based on the EST sequence selected from salt-stressed suppression subtractive hybridization（SSH） cDNA library constructed with a salt-tolerant mutant LM79,a NFU gene,termed IbNFU1,was cloned from sweetpotato（Ipomoea batatas（L.） Lam.） via rapid amplification of cDNA ends（RACE）.The cDNA sequence of 1 117 bp contained an 846 bp open reading frame encoding a 281 amino acids polypeptide with a molecular weight of 30.5 kDa and an isoelectric point（pI） of 5.12.IbNFU1 gene contained a conserved Cys-X-X-Cys motif in C-terminal of the iron-sulfur cluster domain.The deduced amino acid sequence had 66.08 to 71.99% sequence identity to NFU genes reported in Arabidopsis thaliana,Eucalyptus grandis and Vitis vinifera.Real-time quantitative PCR analysis revealed that the expression level of IbNFU1 gene was significantly higher in the roots of the mutant LM79 compared to the wild-type Lizixiang.Transgenic tobacco（cv.Wisconsin 38） plants expressing IbNFU1 gene exhibited significantly higher salt tolerance compared to the untransformed control plants.It is proposed that IbNFU1 gene has an important function for salt tolerance of plants.

Transcriptome profiling reveals insights into the molecular mechanism of drought tolerance in sweetpotato

Sweetpotato,Ipomoea batatas(L.) Lam.,is a globally important food crop and usually grown on arid-and semi-arid lands.Therefore,investigating the molecular mechanism of drought tolerance will provide important information for the improvement of drought tolerance in this crop.In this study,transcriptome analysis of the drought-tolerant sweetpotato line Xushu 55-2 was conducted on Illumina HiSeq 2500 platform.A total of 86.69 Gb clean data were generated and assembled into 2 671 693 contigs,222 073 transcripts,and 73 636 unigenes.In total,11 359 differentially expressed genes(DEGs) were identified after PEG6000 treatment,in which 7 666 were up-regulated and 3 693 were down-regulated.Of the 11 359 DEGs,10 192 DEGs were annotated in at least one database,and the remaining 1 167 DEGs were unknown.Abscisic acid(ABA),ethylene(ETH),and jasmonic acid(JA) signalling pathways play a major role in drought tolerance of sweetpotato.Drought-inducible transcription factors were identified,some of which have been reported to be associated with drought tolerance and others are unknown in plants.In addition,7 643 SSRs were detected.This study not only reveals insights into the molecular mechanism of drought tolerance in sweetpotato but also provides the candidate genes involved in drought tolerance of this crop.

Enhanced Stem Nematode Resistance of Transgenic Sweetpotato Plants Expressing Oryzacystatin-I Gene

Enhanced stem nematode resistance of transgenic sweetpotato （cv. Lizixiang） was achieved using Oryzacystatin-I （OCI） gene with Agrobacterium tumefaciens-mediated transformation. A. tumefaciens strain EHA105 harbors a binary vector pCAMBIA1301 with OCI gene, gusA gene and hptII gene. Selection culture was conducted using 25 mg L-1 hygromycin. A total of 1 715 plants were produced from the inoculated 1 450 cell aggregates of Lizixiang via somatic embryogenesis. GUS assay and PCR analysis of the putative transgenic plants randomly sampled showed that 90.54% of them were transgenic plants. Transgenic plants exhibited significantly enhanced resistance to stem nematodes compared to the untransformed control plants by the field evaluation with stem nematodes. Stable integration of the OCI gene into the genome of resistant transgenic plants was confirmed by Southern blot analysis, and the copy number of integrated OCI gene ranged from 1 to 4. Transgene overexpression in stem nematode-resistant plants was demonstrated by quantitative real-time PCR analysis. This study provides a way for improving stem nematode resistance in sweetpotato.

A geranylgeranyl pyrophosphate synthase gene, Ib GGPS, increases carotenoid contents in transgenic sweetpotato

Geranylgeranyl pyrophosphate synthase(GGPS) plays an important role in the biosynthesis of carotenoids. In a previous study, the IbGGPS gene was isolated from a sweetpotato, Ipomoea batatas(L.) Lam., line Nongdafu 14 with high carotenoid contents, but its role and underlying mechanisms in carotenoid biosynthesis in sweetpotato were not investigated. In the present study, the IbGGPS gene was introduced into a sweetpotato cv. Lizixiang and the contents of β-carotene, β-cryptoxanthin, zeaxanthin and lutein were significantly increased in the storage roots of the IbGGPSoverexpressing sweetpotato plants. Further analysis showed that IbGGPS gene overexpression systematically upregulated the genes involved in the glycolytic, 2-C-methyl-D-erythritol-4-phosphate(MEP) and carotenoid pathways,which increased the carotenoid contents in the transgenic plants. These results indicate that the IbGGPS gene has the potential for use in improving the carotenoid contents in sweetpotato and other plants.

Screening of Bacillus subtilis HAAS01 and Its Biocontrol Effect on Fusarium wilt in Sweet Potato

Fusarium wilt,a disease caused by Fusarium oxysporum f.sp batatas(Fob)is an important disease in sweet potato production.Using endophytic bacteria for biological control of sweet potato diseases is one of the important ways.A Bacillus subtilis with antagonistic effect on Fusarium wilt of sweet potato was isolated from soil by confrontation culture.According to the biological characteristics,16S rDNA sequence analysis,and physiological and biochemical analysis,the Bacillus subtilis HAAS01 was named.A pot experiment was conducted for the biological control experiment of strain HAAS01,and the endogenous hormone content,antioxidant enzyme activity,soluble protein content,and related gene expressions of sweet potato plants were detected.The results showed that the HAAS01 strain could promote the production of endogenous hormones and resist the infection of plant diseases together with defensive enzymes and upregulation of related gene expressions.In summary,Bacillus subtilis HAAS01 was effective in controlling Fusarium wilt of sweet potato and has potential for application and development.

甘薯和Ipomoea lacunosa的种间体细胞杂种植株再生及鉴定

用PEG融合法融合甘薯品种高系14号和近缘野生种Ipomoea lacunosa的原生质体,将融合原生质体培养在含有0.05mg/L 2,4 D和0.5mg/L KT的改良MS培养基中,4～5天后融合原生质体发生第一次细胞分裂。培养12周后,形成直径达1～2mm的小愈伤组织。将这些小愈伤组织转移到添加0.05 mg/L 2,4-D和0.5mg/L KT的MS培养基上,愈伤组织迅速增殖。将其中的70个愈伤组织培养在添加3.0mg/L BAP的MS培养基上,并进一步培养在MS基本培养基上,获得9株再生植株。过氧化物酶同工酶、酯酶同工酶和RAPD分析表明,其中2株再生植株(KL1和KL3)为种间体细胞杂种植株。

甘薯褪绿矮化病毒西非株系RT-LAMP检测方法的建立

【目的】基于逆转录环介导等温扩增技术(Reverse transcription loop-mediated isothermal amplification,RT-LAMP)建立甘薯褪绿矮化病毒(Sweet potato chlorotic stunt virus,SPCSV)西非株系(West African,WA)的可视化检测方法。【方法】针对SPCSV西非株系(SPCSV-WA)的CP核苷酸序列设计4条引物,以感染SPCSV-WA甘薯叶片总RNA为模板,进行一步法RT-LAMP,在65℃条件下反应1 h。扩增产物利用琼脂糖电泳分析和SYBR green I荧光染料显色判断结果,同时对扩增产物的电泳条带进行基因克隆和测序鉴定。利用常规RT-PCR和建立的RT-LAMP方法对14份甘薯样品进行SPCSV-WA检测,比较2种方法的检测结果。【结果】建立的LAMP方法可特异地对SPCSV-WA进行检测,且最低可检测出101拷贝/μL的模板。RT-LAMP产物的克隆测序表明,感染SPCSV-WA甘薯样品的RT-LAMP产物为SPCSV-WA CP基因序列。14份田间甘薯样品检测表明,RT-LAMP与RT-PCR方法检测结果完全一致。【结论】建立的SPCSV-WA RT-LAMP可视化检测方法,是简便、可靠的SPCSV-WA检测方法。

甘薯(Ipomoea batatas)原生质体的分离、培养与根的分化

用甘薯品种农林17号(中紫)的叶柄分离原生质体,对其在添加各种浓度的萘乙酸和激动素的改良细胞薄层培养基中进行悬浮培养。培养1～2 d 后,原生质体再生细胞壁,培养2～3 d 后,再生细胞发生第一次分裂,持续的细胞分裂形成小愈伤组织。悬浮培养的结果表明萘乙酸和激动素的适宜浓度分别为2.0～5.0mg/L 和1.0～5.0mg/L。此后,将小愈伤组织转移到MS 固体培养基上培养,小愈伤组织迅速生长。本试验达到根的分化.

Effects of Drying Processes on the Antioxidant Properties in Sweet Potatoes

The effects of different drying methods （hot-air drying, microwave drying and vacuum-freeze drying） on the antioxidant activity and antioxidants in sweet potato （lpomoea batatas L. Lain.） tubers were investigated to determine the potential drying process. Sweet potato tubers were cut into 5 mm thick slices, steamed at 100℃ for 10 rain, then dried in either hotair, microwave, or vacuum-freeze. The dried sweet potatoes in microwave possessed the highest antioxidant activity, while the lowest activity was observed in hot-air dried samples. The phenolic contents were positively correlated with scavenging activity and reducing power of DPPH^＋. The microwave drying retains the highest antioxidant activity with the highest content of phenolic compounds in dried sweet potatoes. β-carotene and ascorbic acid showed minor contribution to the antioxidant activity in dried sweet potatoes.

甘薯淀粉含量的QTL定位

本研究以高淀粉甘薯品种漯徐薯8号(母本)和低淀粉甘薯品种郑薯20(父本)杂交得到的F1分离群体,选择其中240个单株为材料,以该群体所构建的分子连锁图谱为基础,以2008年和2009年所测定的淀粉含量为指标,采用复合区间作图法并利用QTLMapper2.0软件分析了甘薯淀粉含量的QTL。实验结果表明,检测到了1个主效位点,位于父本郑薯20的Z31连锁群上a02b40.02ds**和a08b37.03fs*两个标记之间,QTL的加性效应为-0.73,解释表型变异的7.70%。定位甘薯淀粉含量相关的QTL,将为发掘与淀粉含量相关的基因奠定基础。

甘薯叶绿体rbcL基因的克隆与序列分析

根据烟草、水稻和菠菜叶绿体的全基因组序列设计引物,以甘薯的叶绿体基因组DNA为模板,PCR扩增包含甘薯叶绿体rbcL完整基因(GenBank登录号为AY942199)在内的一段序列。序列分析表明:此片段的全长为1627bp,包括1443bp的编码区序列在内,推测编码480个氨基酸,同时构建了此片段的限制性酶切图谱。相似性比较显示,此基因编码区序列与烟草、菠菜、小麦、水稻、玉米、矮牵牛、紫花苜蓿、拟南芥、莨菪、葡萄以及甜菜的rbcL基因核苷酸的同源性为85%～98%,氨基酸的同源性为92%～95%。

HPLC法测定药用甘薯西蒙Ⅰ号中咖啡酸的含量

目的 建立测定西蒙 号叶中有效成分含量的方法 ,比较不同年份的西蒙 号叶中咖啡酸的含量差异。方法 采用 HPL C对西蒙 号叶中咖啡酸的含量进行测定。结果 咖啡酸在 10 .33～ 16 5 .2 8μg/ m L 具有良好的线性关系 ,平均回收率为 99.38% ,RSD=1.36 % (n=6 )。结论 该方法灵敏、准确、专属性强 ,适用于西蒙 号药材中咖啡酸的测定。