Effect of Purple Yam(Dioscorea alata L.) on Nutritional and Physiological Functions of Growing Rats

[Objective] This study was to explore the effect of purple yam on the nutritional and physiological functions of rats.[Method] Forty SD rats were randomly divided into four groups with ten rats in each group which were reared with artificial semisynthetic feed added with 10% steamed yam powder.The four groups,the casein（CK） group which was used as the control,the purple yam（PY） group,the Tiegun yam（TY） group and common Huai yam（HY） group,were supplied with feed of equal content of energy,protein and fat.The rats were pair-fed for 56 days to observe changes of relevant nutritional and physiological indices.[Result] There were no significant differences of body weight,food conversion rate and organ indices between rats in PY group and CK group.Mean corpuscular hemoglobin in PY group was significantly lower than that in CK group;hemoglobin showed no significant difference with that in CK group;eosnophils was lower than that in CK group.Low density lipoprotein-cholesterol,total cholesterol and atherogenic index in PY group were lower than that in the other three groups;anti-atherogenic index was the highest among the four groups,while showing no significant difference;triglyceride content was lower than that in CK group.Among the antioxidant indices,the activity of catalase and superoxide dismutase were higher than that in CK group,while malondialdehyde content was lower than that in CK group.[Conclusion] Purple yam showed the trend of reducing the content of blood glucose,total cholesterol,low density lipoprotein-cholesterol,triglyceride,malondialdehyde,and raising the activity of glutathione peroxidase,superoxide dismutase and catalase,thus having certain antioxidative function.

Effect of Synthetic Hormone Substitutes on Rooting of Vine Cuttings in Water Yam (Dioscorea alata L.)

The use of yam vine cuttings as propagules with appropriate synthetic rooting hormones such as IBA (Indole-Butyric Acid) and NAA (Naphthalene Acetic Acid) has previously been reported as successful but expensive. To source for cheaper alternatives, this study compared the effect of some natural and synthetic hormones on rooting of vine cuttings in two varieties of Dioscorea alata. Vine cuttings from three months old water yam varieties were treated separately with 1%, 3% and 5% concentrations of each of the following: neem leaf ash, coconut water, 2,4-D and IBA with water as control. Treated cuttings were planted in triplicates in polythene bags using the completely randomised design and watered once in two days for 49 days. Data collected on rooting percentage, number of roots per plant, mean root length, number and length of new vines were subjected to analysis of variance tests and the means separated using least significant difference tests. A 100% rooting was observed in vines treated with 1% or 3% coconut water and neem ash. These vines also generated significantly greater number of new vines (P < 0.05) compared to those from synthetic hormones. Vines treated with 5% neem produced the highest number of roots (145.33 ± 9.21;P < 0.001) while those treated with 3% neem produced the longest roots (45.3 ± 9.23 cm) followed by those treated with 3% coconut water (24.3 ± 3.48). The study reveals that neem leaf ash and coconut water are better root promoting agents for water yam vines than 2,4-D and IBA and could be tested further for use as natural hormonal substitutes to the synthetic hormones.

Analysis of Tuber Yield- and Maturity- Related Traits in Water Yam （Dioscorea alata L.）

Inadequate yield potential of available varieties and their long growth periods are two of the factors limiting yam （Dioscorea spp.） production. Identifying yield- and maturity-related traits and breeding for them will enhance production. Ten morphological/physiological traits： time of shoot emergence, time of tuber initiation, plant height, shoot dry weight, time of shoot senescence, tuber fresh weight （tuber yield）, tuber number/plant, tuber parenchyma colour, tuber dry matter content and tuber dormancy period were assessed in eight accessions of D. alata L. （water yam） on the field in 2008 and 2009. Tuber yield-related traits were identified as shoot dry weight and time of shoot emergence. Shoot dry weight had the strongest positive effect; time of shoot emergence had a negative effect. High yielding accessions had a high shoot dry weight, but were low in tuber dry matter content. Uniform tuber parenchyma colour was the sole trait related to tuber maturity, but early and late senescing accessions did not consistently differ in the trait. TDa 00/00103 is high yielding and early maturing and may be used as a parent for breeding for high yield and early maturity in D. alata.

叶喷水杨酸对山药(Dioscorea alata L.)地下块茎蔗糖—淀粉转化影响(英文)

【目的】阐明叶喷水杨酸(SA)对山药地下块茎蔗糖—淀粉转化的影响,为了解山药蔗糖转化机制、提高其淀粉形成提供参考。【方法】设置SA 0.0(对照)、0.5、1.0和5.0 mmol/L 4个处理,在山药(Dioscorea alata L.)"白扁"地下块茎形成的早期和后期分别进行叶面喷施,定期采样测定地下块茎主要碳水化合物含量和蔗糖裂解与淀粉形成的相关酶活性。【结果】除5.0 mmol/L SA处理的后期地下块茎总可溶性糖(TSS)含量急剧增加外,地下块茎的TSS、蔗糖、葡萄糖、果糖、淀粉、直链淀粉(AM)、支链淀粉(AP)和纤维素的含量在其他处理间的变化趋势相同。与对照相比,0.5mmol/L与5.0 mmol/L SA处理对山药地下块茎的影响作用相反,前者不仅显著提高了蔗糖合成酶(SuSase)、酸性转化酶(SAInv)、细胞壁结合酸性转化酶(CWBAInv)、中性转化酶(NInv)等酶的活性,而且显著增加腺苷二磷酸焦磷酸化酶(AGPase)、可溶性淀粉合成酶(SSS)、颗粒结合淀粉合成酶(GBSS)、淀粉分支酶(SBE)等酶的活性,1.0 mmol/L仅在块茎发育中期对上述酶有微小的促进作用。所有SA处理中,虽然蔗糖含量与SuSase及淀粉合成相关酶的活性呈不显著正相关,但蔗糖与总可溶性糖含量的比率与这些酶活性及淀粉含量成显著正相关。葡萄糖、果糖含量及它们所占总可溶性糖的比率与上述酶的活性分别呈显著负相关,葡萄糖与果糖的比率与上述酶的活性无显著相关性,蔗糖与葡萄糖、果糖的比率均与AGPase、SSS、GBSS的活性呈显著正相关。【结论】叶面喷施SA在山药地下块茎发育过程中通过作用于蔗糖裂解和淀粉合成相关酶的活性来影响蔗糖的运输和流向,小于1.0 mmol/L的SA通过提高酶活性来促进蔗糖转运入山药地下块茎并转化成淀粉,而其他浓度SA具有相反的作用。

Identification of Polysaccharides from Chinese Yam(Dioscoreae opposite “Qi”) by Infrared Spectroscopy

In this study, the structure of polysaccharides from Chinese yam （Dioscoreae opposite ＂Qi＂） was analyzed and identified by infrared spectroscopy within an infrared spectral range of 400-4 000 cm^-1, Characteristic absorption peaks were observed at 840 cm^-1 （α-glucosidic bond）, 759.21 cm^-1 （xylose）, 830.87 cm^-1 （rhamnose）, 812.81 cm^-1, 876.60 cm^-1 （mannose） and 842.64 cm^-1 （arabinose） in infrared spectra of polysaccharides from D. opposite ＂Qi＂, indicating that D. opposite ＂Qi＂ polysaccharides exist mainly in the form of α-glucosidic bonds, including xylose, rhamnose, mannose and arabinose. The experimental results could provide the basis for quantitative analysis, development and application of polysaccharides from D. opposite ＂Qi＂.

In vitro modulation of TH1 and TH2 cytokine expression by edible tuber of Dioscorea alata and study of correlation patterns of the cytokine expression

The underground tuber of Dioscorea alata is a palatable food and is also claimed to have therapeutic effects.Various groups of researchers demonstrated different activities of this tuber such as antioxidant,hepatoprotective,anti-ulcer and anti-diabetic activities.Therefore,the aim of the present study was to evaluate the immunomodulatory potentialities of 70%hydro-methanolic extract of D.alata underground tubers by investigating different parameters like the expression of interferon gamma(IFN-),interleukin(IL)-2,IL-4 and IL-10,in addition to its effect on the proliferation of murine splenic T-lymphocytes in vitro.Results demonstrated that D.alata can actively polarize the TH0 lymphocyte population towards the expression of TH1 immune response by up-regulating the IFN-and IL-2 expression and down-regulating the IL-4 and IL-10 expression.The tuber extract also proved to possess mitogenic activity as evidenced by the proliferation of lymphocytes in vitro.©2014 Beijing Academy of Food Sciences.Production and hosting by Elsevier B.V.All rights reserved.

Polyphenol Oxidase Activity and Inhibition in White Yam （Dioscorea Rotundata. Var. Laasirin） Chips as African Fries for Human Consumption

Polyphenol oxidase, a bi-functional enzyme, has been implicated in enzymatic browning of yam and other tubers in a negative way. The objective of this present study was to examine the activity of polyphenol oxidase in Dioscorea rotundata. Var. laasirin and the efficiency of heat and chemical treatments in inhibiting this enzyme. Crude Polyphenol Oxidase （PPO） of Dioscorea rotundata.Var. Laasirin was isolated and the kinetics studied using the lineweaver-burk plot. The activity of the enzyme was evaluated using spectrophotomeric method. Yam PPO catalyzes oxidation of various substrates with catechol being the most readily oxidized substrate. The Michaelis-Menten constant （Km） and maximum reaction velocity （Vmax） for yam PPO were 0.00037 and 0.3125 respectively. Inhibition data showed that the enzyme had least activity （71.70） when blanched at 95℃ for 7 mins with chemical treatment involving a combination of 0.5% Sodium metabisulphite （Food grade） and 0.5% Ascorbic acid （Food grade）. The activity was highest （83.02） when it was blanched at 95 ℃ for 7 rains. This study has shown that it is possible to inhibit polyphenol oxidase activity in white yam using the chemical pretreatments and processing conditions described in this study for possible adoption in the production of packaged frozen yam chips by food industries.

Application of Prochloraz-nano-titanium Dioxide Complex Fresh-keeping Agent in Refrigeration of Dioscorea alata Lirm. sp.

Prochloraz diluents( 450 ×,475 ×,500 ×) were added with different concentrations of nano-titanium dioxide( Ti O2)( 0. 8%,1. 0%) respectively to prepare complex fresh-keeping agents,which were applied in the refrigeration of Dioscorea alata Lirm. sp. With rot index,weight loss rate,browning degree( BD),total soluble solids( TSS) content,malondialdehyde( MDA) content,polyphenol oxidase( PPO) activity and peroxidase( POD) activity,DPPH· scavenging rate as evaluation indexes,the preservation effect of the prepared freshkeeping agents on D. alata during the cold storage period was analyzed. The results showed that prochloraz added with nano-titanium dioxide significantly prolonged the storage life,reduced the rot rate and weight loss rate,and slowed the loss of pulp of D. alata. The preservation effect of complex fresh-keeping agent of prochloraz diluent( 475 ×) and nano-titanium dioxide( 1. 0%) was better than that of other treatments.

Effect of Plant Growth Hormones and Liquid Fertilizer on Rooting and Tuberization of Yam (<i>Dioscorea rotundata</i>Poir.) Vine Cuttings

Vine cutting is an effective solution to solve the problem of seed availability in yam cultivation. This study was conducted to improve the recovery and rooting rate of vine cuttings of Dioscorea rotundata. Two-node cuttings from five (5)-month-old hybrid plants were grown in liquid media consisting of phytohormones (AIA3 and GA3) and liquid fertilizer (NPK 8-8-8) at different concentrations. Observations were made weekly from the 21st day after transplanting and focused on the survival rate of the cuttings, the number of roots emitted and the number of minitubers initiated. The results obtained showed a significant effect of the different growing media on the survival rate, rooting and production of minitubers. The best survival rates were obtained for cuttings grown in NPK (8-8-8) at 0.25% (100%) and AIA3 at 25 ppm (93.3%). The highest averages root number was recorded with growing media containing 0.25% NPK 8-8-8 (20.3) and 25 ppm AIA3 (17.7). Growing media with 0.25% NPK (8-8-8) and 25 ppm AIA3 provided the highest average numbers of minitubers initiated, respectively 5 and 4.6. Growing medium containing 0.25% NPK 8-8-8 has been identified as the one that allows better roots emission and minitubers production by yam vines cuttings.

Effect of 24-Epibrassinolide on Growth of <i>in Vitro</i>Shoot Tips of Different Yam (<i>Dioscorea</i>Spp.) Species

In this work we compared the effect of the growth regulator content of the culture medium on the growth of in vitro shoot tips of five yam accessions belonging to four yam species (one Dioscorea alata, one D. rotundata, one D. cayenensis and two D. trifida). Medium S contained 0.6 μM benzyl adenine, 1.07 μM naphthalene acetic acid and 0.23 μM gibberellic acid while medium EBR contained 0.23 μM gibberellic acid and 0.1 μM 24-epibrassinolide. After 2 months of culture, oxidation level was significantly reduced on medium EBR compared to medium S for four of the five accessions tested. By contrast, medium EBR did not have any positive effect on shoot length since length of shoots produced after 2 months of culture on medium S and EBR were similar, except with accession 3-45T, for which shoot length was shorter on medium S compared to medium EBR. These results underline the potential of 24-epibrassinolide to reduce oxidation phenomena during in vitro culture and call for its utilization for regeneration of cryopreserved yam shoot tips, which is often impeded by oxidation phenomena.

Effect of Curing Treatments on Seven Key Farmers’ Yams (<i>Dioscorea</i>spp.) in Ghana

Curing of freshly harvested yams (Dioscorea spp.) is a process for wounded yams during harvest to heal. In this work the effectiveness of straw, polypropylene and jute sack on curing of seven key farmers’ yam varieties over a duration of 7, 14 and 21 days was studied. Seven key farmers’ yam varieties identified as Pona, Lariboko, Dente, Mutwumudoo, Serwah belonging to D. rotundata, Matches and Akaba belonging to D. alata were studied under different curing treatments. The percentage weight loss of yam tubers varied among the treatments over curing period. Curing under jute sack showed all yam varieties had weight losses less than 2.0%, within 7 days of curing. Five different varieties had weight loss less than 2.0% except Dente under the straw treatment. Mutwumudoo variety showed the highest water loss (8.4%) for polypropylene sheet and 6.9% for Lariboko in the control treatment. During 7 days curing the control and polypropylene treatment did not support yam curing. After 14 days of curing of tubers, similar tends were observed as in 7 days curing. After 14 days of curing under jute sack, percentage weight loss of the tubers ranges from 2.0% - 3.7%. In the straw treatment, the percentage weight loss ranges between 1.0% - 4.7% in all other varieties except Dente (D. rotundata) (8.2%). Polypropylene sheet treatment showed the highest percentage weight loss in Mutwumudoo variety (18.4%). A similar trend was observed for the yam tubers cured for 21days as percentage weight loss of tubers under jute sacks was 2.5 – 9.8%. Curing temperature and humidity ranged between 27&degC - 40&degC and 87% - 100% rh for yam tubers under the three different treatments of polypropylene, jute and straw. However, the control treatment recorded lower humidity of 60% - 80% rh. Curing material, duration, climatic conditions and yam varieties influenced curing and Serwah variety, which is a D. rotundata is the best bet yam variety to cure under jute sack for 7, 14 and 21 days of curing.

Acetone Extract of <i>Dioscorea alata</i>Inhibits Cell Proliferation in Cancer Cells

Dioscorea spp., White Yam has been shown to exhibit a wide range of nutritional and medicinal properties. However, the compounds associated with its medicinal functions have not been fully examined. The purpose of this study was to generate a chemoinformatic profile of the bioactive compounds present in Dioscorea. alata (D. alata) and to characterize their putative anti-cancer properties using prostate (DU145) and lung (A549) cancer cells. Chemoinformatic profiling of D. alata resulted in five bioactive extracts: hexane (DaJa-1), ether (DaJa-2), acetone (DaJa-3), ethanol (DaJa-4) and water (DaJa-5) were generated. The analytes present in the five bioactive extracts were dissolved in 0.1% DMSO and their anti-cancer activity were determined. We observed that the acetone extract (DaJa3) was the only extract capable of inducing greater than 90% cell death of DU 145 cell at 100 μg/mL. The order of growth inhibition of the extracts in DU-145 cell is DaJa-3 (IC50, 31.45 μg/mL) > DaJa-4 (IC50 60 μg/mL) > DaJa-1 (IC50 > 100 μg/mL) ≥ DaJa-2 (IC50 > 100 μg/mL) ≥ DaJa-5 (IC50 > 100 μg/mL). MTT cell viability, dye exclusion, caspase activity and microscopic assessment of apoptotic cells demonstrated that DaJa-3 displayed cytotoxicity to both lung and prostate cancer cells. The A549 cells were more sensitive toward DaJa-3 with an IC50 value of 22.28 μg/mL (CI 28.42 to 36.63 μg/mL), compared to that of DU145 cells with an IC50 value of 31.45 μg/mL (CI 27.58 to 35.86 μg/mL). It was also observed that DaJa-3 induces differential anti-proliferative activity in the cancer cells. The apoptotic response induced by DaJa-3 paralleled the level of cell cytotoxicity observed in both cell lines. DaJa-3 induces G2 phase cell cycle arrest in DU145 cells but G1 arrest in A549 cells. The level of key apoptotic regulator proteins was upregulated, suggested that DaJa-3 may be mediating its anti-cancer effect through activation of the intrinsic apoptotic pathway. Altogether, our data indicates that DaJa-3 derived from a staple food source (white Yam) contains unique active compounds that have specific biological properties that may prevent certain types of cancer or specific types of cancer.

Cultivar and Soil Fertilizer Treatment Affect Seed Production of Sweet Yellow Yam (<i>Dioscorea dumetorum</i>) on Highly Acidic Soils of the Western Highlands Region of Cameroon

The popularization of Dioscorea dumetorum (Dioscoreaceae), a nutritious yam species is still marginal due to constraints such as the low interest of research, poor cultural practices, insufficient and expensive seeds, pests, and diseases. The latter pushes producers to use about 50% of their harvest as seed for the next planting season. The lack of a specific fertilizer formulation for yam production on the oxysols of Cameroon is another constraint. This study was aimed at enhancing the availability of quality seeds through the characterization of five yam accessions. One experiment was performed to determine the effect of cultivar and origin of tuber sets on their germination rate. The second concerned the evaluation of cultivars and soil treatment effects on agronomic parameters of yam seedlings. Yam cultivars were subjected to nine fertilizer formulations as follows: T0: no fertilizer;T1: mycorrhizal fungi (MF) + 150 g manure + peanut waste;T2: 25 g chemical fertilizer (20.10.10);T3: MF + peanut waste;T4: 16 g chemical fertilizer (12.6.20);T5: 25 g (20.10.10) +100 g CaO + 150 g manure;T6: 100 g CaO + 150 g manure;T7: 20 g tropicote + 2 g DAP (Diammonium phosphate, a reference starter fertilizer coded N18P46) + 100 g CaO + 150 g manure;and T8: mycorrhiza. These treatments were tested in a factorial design. Results show that Ibo sweet 3 and Mabondji sweet white 1 yam accessions were less affected by anthracnose disease on the aerial parts. Guzang 1 showed the best germination rate and yield, making it appropriate for cultivation in the region. Soil treatments, T2, T5, T7 and T8 significantly increased the yield of yam cultivars. Mycorrhiza treatment alone gave a better response to seed weight, indicating the interest of this biofertilizer as a solution for good seedling production. These fertilizer treatments can be recommended to farmers for more seed production with optimum seed weight (300 g).

Farmer Participatory Breeding - The Foster Parent in the Breeding of Dioscorea spp. in Ghana

Yam （Dioscorea spp.）, has been aptly described as an orphan crop. It has suffered institutional neglect from time immemorial. Until this study there were no formally released yam varieties in Ghana. The farmer participatory breeding approach was adapted to fast-track the development and release of three new yam varieties in Ghana. This paper uses the breeding process as a case study and conducts a SWOT analysis to provide guidelines for breeding for crops in Low External Input Agriculture. It was faster than conventional breeding in varietal development. Scientific quality of Farmer Participatory Breeding is as good as conventional breeding. Farmer Participatory Breeding is a must for breeding yam in Ghana. Ultimately, three genotypes 2000/001, KUP2000/001 and TDr89/02665 were accepted and released as new varieties ＂CRIKukrupa＂, ＂CRIPona＂ and ＂Mankrong Pona＂ respectively in March 2005. Danger of omission of some promising genotypes in the course of varietal development and danger of opinion group cabalizing the group discussions were identified as potential threats to the approach. Effective research-extension-farmer linkage was identified as extremely vital to the success of the approach. Farmer participatory breeding process was also sustainable and more efficient than conventional breeding in varietal selection in yam breeding.

Biology of Planococcus citri (Risso) (Hemiptera: Pseudococcidae) on Five Yam Varieties in Storage

Yam is an important staple cash crop, which constitutes 53% of total root and tuber consumption in West Africa. It is a cheap source of carbohydrate in the diets of millions of people worldwide and in tropical West Africa. However, attack by Planococcus citri results in shriveling of the tubers, making them become light and unpalatable. They also lose their market value. The total number of eggs laid, incubation period, developmental period and adult longevity of P. citri on stored yam Disocorea species were studied on five yam varieties namely Dioscorea rotundata var. Pona, Dioscorea rotundata var. Labreko, Dioscorea rotundata var. Muchumudu, Disocorea alata var. Matches and Dioscorea rotundata var. Dente in the laboratory with ambient temperatures of 26.0&#176C - 30.0&#176C and relative humidity of 70.0% - 75.0%. The mean life spans of the female insect that is from hatch to death on Dioscorea rotundata var. Pona, Dioscorea rotundata var. Labreko, Dioscorea rotundata var. Muchumudu, Disocorea alata var. Matches and Dioscorea rotundata var. Dente were 62.4, 63.5, 66.8, 67.3 and 69.8 days, respectively and those of the male were 23.8, 25.3, 29.6, 30.2 and 33.5 days, respectively. The adult female lived longer than the adult male. The findings showed that citrus mealybug preferred Dioscorea rotundata var. Pona to the rest of the varieties, as it developed faster and laid more eggs (497.0 eggs) on it than on the other varieties. This implies that citrus mealybug multiplies faster and destroys Dioscorea rotundata var. Pona tubers in storage faster than on the other varieties. Therefore, Dioscorea rotundata var. Dente should be the preferred yam for long-term storage.

山药块茎生长膨大相关基因的筛选与分析

为筛选山药块茎生长膨大相关基因,采用生物信息学方法,对山药块茎发育前期和中期构建的不同发育阶段抑制性消减杂交(suppression subtractive hybridization,SSH)文库进行分析。结果表明:山药块茎发育前期与中期差异表达基因(differential expression genes,DEGs)序列主要涉及九大类,其中发育调控占比最大(27.1%),其他依次为细胞组织结构(14.0%)、物质代谢(11.2%)、生物合成(4.7%)等。初步筛选出泛素-连接酶体(F-box associated,F-box)、碳酸酐酶(carbonic anhydrase,CAs)、核苷二磷酸激酶(nucleoside diphosphate kinase,NDPK)、氨基酸透性酶(amino acid permease)、糖基转移酶(glycosyl transferase)、α-淀粉酶(α-amylase,AMY)等候选基因,它们可能与细胞增殖、细胞伸长、激素代谢、酸碱环境调节及功能物质代谢物等功能有关,参与调控山药块茎的生长膨大。

山药颗粒结合型淀粉合成酶基因DaGBSS的克隆与分析

颗粒结合型淀粉合成酶(granule-bound starch synthase,GBSS)是一种能够决定直链淀粉生物合成的关键性酶。通过对山药转录组分析、分子克隆获得一个具有完整ORF的DaGBSS基因,cDNA片段长度为1845 bp,编码614个氨基酸。生物信息学分析结果显示DaGBSS蛋白为一酸性稳定蛋白,含有淀粉合酶催化和糖基转移酶2个功能结构域。多序列比对结果显示:糯米山药DaGBSS蛋白与所选的物种具有较高的同源性,且含有典型的功能结构域;生物进化分析结果显示DaGBSS蛋白与圆形薯蓣亚种进化亲缘关系最近。对采收15 d山药块茎进行处理,qRT-PCR、指标分析结果显示DaGBSS基因在山药块茎的表达存在明显的时空差异性,且在距离地表位置最远的部位DaGBSS基因的表达量、GBSS和直链淀粉的含量均为最高。研究通过对山药块茎淀粉合成的早期阶段进行生理、关键调控因子的克隆分析,为探究山药淀粉合成的调控提供参考,同时对糯米山药的分子育种提供了重要的基因资源。

不同肉色脚板薯营养成分和功能成分分析

以紫色、白色2种肉色脚板薯为试材,采用高效液相色谱法、电感耦合等离子体发射光谱法(ICP-OES)和pH示差法对其氨基酸、单糖、尿囊素、薯蓣皂苷、微量元素及总花色苷含量进行检测分析,并测定水分、蛋白质、淀粉等成分含量。结果表明:2种不同肉色脚板薯营养成分和功能成分存在一定差异性。白色肉脚板薯蛋白质含量显著高于紫色肉,而水分和淀粉含量显著低于紫色肉;微量元素Bi、Rb和Se含量为白色>紫色,Mo、Ca、Mg元素为白色<紫色,其他元素差异不明显;必需和非必需氨基酸总含量为白色>紫色;富含精氨酸,含量为白色>紫色,分别为297.96和97.08 mg/kg;富含尿囊素,含量为白色>紫色,分别为30.03和24.53 mg/kg;单糖、薯蓣皂苷、总花色苷含量均为白色<紫色,单糖组成为葡萄糖>半乳糖>甘露糖>半乳糖醛酸>木糖>核糖>阿拉伯糖>葡萄糖醛酸>鼠李糖>岩藻糖。

紫参薯的包埋玻璃化超低温保存

以紫参薯带芽茎段为材料,采用2%海藻酸钠和0.1mol/L氯化钙凝胶系统制备包埋珠,液氮保存,以茎段细胞活力和包埋珠成活率为指标筛选获得有关参数适宜水平,比较冻后再生苗与常温苗形态及生理指标.结果表明:紫参薯试管苗经4℃锻炼6d后,无菌条件下制备其带芽茎段包埋珠,接种到MS+2 mg/L KT+0.2 mg/L NAA+0.5mol/L蔗糖液体培养基中预培养1d,转入MS+2 mol/L甘油+0.4 mol/L蔗糖溶液中室温下装载40min,在玻璃化保护剂PVS2中脱水40min,更新PVS2后迅即液氮保存,24h后置于37℃水浴中化冻5min,用MS+2mg/L KT+0.2mg/L NAA+0.8mol/L蔗糖溶液洗涤3次(每次10min),然后转入MS+2mg/L KT+0.2mg/L NAA+30g/L蔗糖+1g/L活性炭固体培养基中,暗培养7d后转至光照下培养14d,该包埋珠成活率可达60%.冻后再生苗诸多形态和生理指标与常温苗差异不具有统计学意义.

山药SuSy基因全长cDNA序列的结构、进化和表达

【目的】阐明山药蔗糖合成酶(SuSy,EC 2.4.1.13)基因家族的成员及其功能。【方法】利用RT-PCR和RACE技术从大薯(Dioscorea alata)地下块茎中分离到1个SuSy基因(DaSuSy1)全长cDNA序列,并用DANSTAR和Clastal W等软件分析该序列的结构特征和分子进化,采用RT-PCR和Northern杂交对该基因的时空表达进行分析。【结果】DaSuSy1全长cDNA序列大小为2673bp,其中最大开放阅读框(ORF)、5'端和3'端的非翻译区分别含有2445bp、7bp和221bp,而且3'端的非翻译区含1个24nt的Poly(A+)尾;最大ORF可编码814个氨基酸,分子量为92.76kD,等电点为6.42,含有蔗糖合成酶和葡糖基转移酶两个保守功能域及两个磷酸化位点,即N端的Ser10和C端的SNLDRRET781 RR(Ser774～Thr781)。该基因在全长cDNA序列、编码区cDNA序列及其编码氨基酸序列的水平上与GenBank中所选已知物种SuSy基因相应序列的同源性分别达45.3%～71.3%、45.8%～74.8%和50%～84.7%,与禾本科植物SuSy基因家族中一些成员亲缘关系最近。DaSuSy1在非光合器官中表达,其中地下块茎表达最为强烈,而且从块茎形成初前期开始表达一直增强至盛中期,此后逐渐减弱。【结论】DaSuSy1是山药SuSy基因家族成员,归为单子叶植物SuSy基因的组别,仅在非光合器官中表达编码负责蔗糖-淀粉转化功能的SuSy同工型。