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 Functional Analysis of Lycopene ε-Cyclase (IbLCYe) Gene from Sweetpotato, Ipomoea batatas (L.) Lam.

This paper reported firstly successful cloning of lycopene ε-cyclase （lbLCYe） gene from sweetpotato, lpomoea batatas （L.） Lam. Using rapid amplification of cDNA ends （RACE）, lbLCYe gene was cloned from sweetpotato cv. Nongdafu 14 with high carotenoid content. The 1 805 bp cDNA sequence oflbLCYe gene contained a 1236 bp open reading frame （ORF） encoding a 411 amino acids polypeptide with a molecular weight of 47 kDa and an isoelectric point （pI） of 6.95. IbLCYe protein contained one potential lycopene ε-cyclase domain and one potential FAD （flavinadenine dinucleotide）/NAD（P） （nicotinamide adenine dinucleotide phosphate）-binding domain, indicating that this protein shares the typical characteristics of LCYe proteins. The gDNA oflbLCYe gene was 4 029 bp and deduced to contain 5 introns and 6 exons. Real-time quantitative PCR analysis revealed that the expression level of IbLCYe gene was significantly higher in the storage roots of Nongdafu 14 than those in the leaves and stems. Transgenic tobacco （cv. Wisconsin 38） expressing [bLCYe gene accumulated significantly more ^-carotene compared to the untransformed control plants. These results showed that lbLCYe gene has an important function for the accumulation of carotenoids of sweetpotato.

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.

Identification of QTLs for Starch Content in Sweetpotato(Ipomoea batatas(L.) Lam.)

Sweetpotato （Ipomoea batatas （L.） Lam.） breeding is challenging due to its genetic complexity. In the present study, interval mapping （IM） and multiple quantitative trait locus （QTL） model （MQM） analysis were used to identify QTLs for starch content with a mapping population consisting of 202 F1 individuals of a cross between Xushu 18, a cultivar susceptible to stem nematodes, with high yield and moderate starch, and Xu 781, which is resistant to stem nematodes, has low yield and high starch content. Six QTLs for starch content were mapped on six linkage groups of the Xu 781 map, explaining 9.1-38.8% of the variation. Especially, one of them, DMFN 4, accounted for 38.8% of starch content variation, which is the QTL that explains the highest phenotypic variation detected to date in sweetpotato. All of the six QTLs had a positive effect on the variation of the starch content, which indicated the inheritance derived from the parent Xu 781. Two QTLs for starch content were detected on two linkage groups of the Xushu 18 map, explaining 14.3 and 16.1% of the variation, respectively. They had a negative effect on the variation, indicating the inheritance derived from Xu 781. Seven of eight QTLs were co-localized with a single marker. This is the first report on the development of QTLs co-localized with a single marker in sweetpotato. These QTLs and their co-localized markers may be used in marker-assisted breeding for the starch content of sweetpotato.

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.

Development of a Process for Formulating Infant Flours from the Almonds of <i>Treculia obovoidea, Terminalia catappa</i>Linne as well as <i>Ipomoea batatas</i>Lam Leaves

In response to the malnutrition problem affecting children in Congo Brazzaville, we made three cooking-type infant flours from Treculia obovoidea, Terminalia catappa L. almonds and Ipomoea batatas L. leaves. The nutritional quality of the three infant flours we developed indicates 11.07% - 12.47% protein content, 9.92% - 14.87% fat content, 58.85% - 68.06% carbohydrate content, 1.50% - 2.18% ash and an energy intake varying between 399.84 and 439.37 Kcal. Functionally, our prepared flours have a water absorption capacity between 219.05 and 317.86 mL/g, an oil absorption capacity of 0.19 mL/g, a water solubility index varying from 29.66 - 41.03 and a swelling capacity of 250% - 320%.

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.

基于ISSR指纹的甘薯食用品种的遗传多样性分析

运用ISSR分子指纹技术检测甘薯基因组DNA的多态性,是鉴定甘薯遗传多样性和亲缘关系有效的方法之一。本研究选用6个ISSR标记对17份甘薯品种进行了DNA指纹扩增,共扩增出55条谱带,其中多态性谱带50条,多态性水平为90.91%;UBC825引物扩增出带型最多,有16种;根据Nei’s遗传距离计算获得的聚类树状图表明,在GS为0.625时,参试的17份甘薯品种分为4个组群;遗传相似性分析表明,顶芽菜用品种间遗传相似系数最高0.877,叶柄食用品种和烤薯型品种之内的遗传相似系数分别为0.778和0.740。结果表明甘薯主要食用间具有较好的遗传多样性,但同类型品种间却又有较高的遗传相似性,这类品种需要引进或创制新资源。

甘薯IbERF071基因的克隆及表达特性分析

为探究甘薯(Ipomoea batatas(L.)Lam.)IbERF071基因在抗蔓割病中的调控作用,根据甘薯转录组数据,从甘薯高抗蔓割病品种‘鄂薯11’中克隆获得1个编码乙烯应答的基因,命名为IbERF071,并对其进行生物信息学分析,以及侵染蔓割病病原菌、外施茉莉酸甲酯和乙烯利的基因表达模式分析。结果表明,IbERF071基因的CDS序列大小为864bp,共编码287个氨基酸;在其编码的氨基酸序列的第79~142位包含1个AP2保守结构域,在第205~254位包含1个卷曲螺旋;IbERF071氨基酸序列与牵牛InERF氨基酸序列的相似度高达89%以上,具有高度同源性,且在系统发育树上也聚为同一支;IbERF071蛋白不稳定指数、脂肪系数和总亲水性平均系数分别为48.26、47.35和-1.003,分子质量为32215.31ku,等电点为5.12,表明该蛋白是一种不稳定的亲水性蛋白质;IbERF071蛋白二级结构中,随机卷曲、α螺旋、延伸链和β转角所占比例分别为61.67%、26.83%、8.01%和3.48%,三级结构中,22%的氨基酸残基结构置信度达到64.06%,IbERF071蛋白定位于细胞核上,没有跨膜蛋白且不存在跨膜螺旋区;IbERF071基因启动子区包含真核生物启动子基本元件胁迫响应元件、茉莉酸甲酯响应元件、低温响应元件MYC、干旱诱导元件ERE、脱落酸效应元件、植物防御响应元件、水杨酸响应元件TCA等30种顺式作用元件;IbERF071基因在根、茎、叶中均有表达,且在根中表达量显著高于茎、叶,经蔓割病原菌侵染后,IbERF071基因的相对表达量显著升高,并在侵染2h时表达量达到峰值,茉莉酸甲酯处理72h和乙烯利处理48h后,其表达量显著提高。综合来看,甘薯IbERF071蛋白属于AP2/ERF超级家族,具有较高的保守性,IbERF071在调控甘薯抗蔓割病菌中的功能以及JA和ET介导的激素信号转导途径的过程中起重要作用。

甘薯低温胁迫基因IbICE1的克隆及表达分析

克隆甘薯(Ipomoea batatas(L.)Lam.)低温胁迫基因Ib ICE1,对其进行序列分析及低温胁迫下表达水平分析,探讨Ib ICE1对甘薯耐低温胁迫能力的影响。以辽薯36为试验材料,利用RACE技术克隆甘薯Ib ICE1基因,Ib ICE1基因的c DNA全长2150bp,包含1611bp完整的开放阅读框,该基因编码536个氨基酸残基,分子量58.26 k D,等电点5.72。进化树分析表明,Ib ICE1同玉米和拟南芥ICE1基因亲缘关系较近。Ib ICE1蛋白C端含有一个典型的b HLH结构域,并与其他植物的ICE1蛋白具有较高的同源性。采用RT-PCR研究该基因在低温处理时的表达量及在甘薯不同组织中的表达量,结果表明,该基因的表达受低温胁迫诱导,在甘薯的茎、叶和根均有表达,其中叶中表达量最高,推测Ib ICE1基因在甘薯耐低温胁迫中发挥重要作用。

氮素不同控释期对甘薯光合特性及干物质积累与分配的影响

以甘薯[Ipomoea batatas(L.)Lam.]品种济薯25为试材,在大田条件下,设置控释期为30 d(T30)、50 d(T50)、70 d(T70)、90 d(T90)4个氮素控释肥处理,以施用等量养分含量的普通复合肥作为对照(CK),研究不同氮素控释期对甘薯光合特性及干物质积累与分配的影响。结果表明,氮素适当控释(控释期30~70 d)提高了甘薯中后期(80~160 d)叶片光合性能,促进了干物质向地下部的快速积累和转运分配,甘薯中后期叶片光合指标、地下部干物质积累(积累量和积累速率)和分配(分配比例和根冠比)指标均明显高于对照,其中以T50、T70较好,收获期(160 d)2个处理净光合速率、叶绿素SPAD、地下部干物质积累量、根冠比分别比对照提高了14.01%、11.32%、21.75%、18.48%和15.62%、11.84%、20.65%、18.84%;当控释期达90 d时,后期(120~160 d)地下部干物质积累与分配指标均低于对照,说明氮素控释期过长不利于甘薯后期干物质向地下部的快速积累和转运分配。

优质甘薯品种湛薯16的选育及栽培技术

湛薯16是湛江市农业科学研究院采用五圃制法,从徐紫薯3号自然杂交后代中选育出来的优质甘薯[Ipomoea batatas(L.)Lam.]品种。在2019—2020年南方薯区甘薯新品系多点鉴定试验中,湛薯16鲜薯平均产量33280.05 kg/hm^(2),薯干平均产量9748.95 kg/hm^(2),淀粉平均产量6364.35 kg/hm^(2),平均干物率29.14%。该品种鲜薯产量高、熟食口感佳,中抗蔓割病,适宜按照栽培技术推广。

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.

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.

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.

AFLP Fingerprinting and Genetic Diversity of Main Sweetpotato Varieties in China

AFLP fingerprinting of the 98 main sweetpotato varieties planted in China has been constructed. Using 17 AFLP primer combinations which were selected from 1 208 primer combinations and generated the most amounts of polymorphic bands, AFLP analysis of the 98 main sweetpotato varieties gave a total of 410 clear polymorphic bands with an average of 24.12 polymorphic bands per primer combination. Each one of the 98 sweetpotato varieties could be clearly distinguished by EcoR I-cta/Mse I-ggc primer combination which generated the most polymorphic bands. AFLP-based genetic distance ranged from 0.0546 to 0.5709 with an average of 0.3799. The dendrogram based on AFLP markers indicated that sweetpotato varieties coming from the same regions or having same parents were clustered in the same groups. Analysis of molecular variance （AMOVA） revealed greater variations within regions （94.08%） than among regions （5.92%）. Thus, the genetic variations mainly existed within regions, while the variations among regions were very low in the tested sweetpotato varieties. Significant genetic variations existed between ＂Northern＂ and ＂Southern＂ sweetpotato varieties when Yangtze River was used as the dividing line.

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.

甘薯抗病相关基因TAO1-like的TRAP分析

NBS-LRR是植物中已分离抗病基因最大的一类,TargetofAvrBOperation(TAO1)属于NBS-LRR类基因。以甘薯[Ipomoea batatas(L.)Lam.]抗病相关的TAO1基因作为靶标基因,设计出1条固定引物,与11条随机引物组合成11对引物。利用这11对引物对甘薯品种鄂薯11、鄂紫薯13进行TRAP-PCR扩增,发现11个引物组合扩增出清晰条带,且表现出良好的多态性。该研究获得与TAO1-like基因相关联的TRAP标记,该标记可进行甘薯群体的遗传多样性分析,为甘薯的抗病育种奠定基础。

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.