高等植物果聚糖合成途径、相关基因和功能的研究进展

果聚糖是由蔗糖与一个或多个果糖基相连接的聚合物,是一类重要的碳水化合物和渗透调节物质,可提高植物的抗逆性;果聚糖还是一类重要的功能性食品,对人体健康有多种促进作用。植物是果聚糖的主要来源,其合成过程涉及到多种果糖基转移酶,不同的果糖基转移酶组合形成不同类型的果聚糖。较为系统地综述了高等植物果聚糖合成的代谢路径、相关基因、果聚糖的功能及应用前景等方面的研究进展。     

食用菊苣引种试验

菊苣是双子叶植物纲菊科舌状花亚科菊苣属植物,营养价值很高,富含多种糖分、矿物元素,其中果聚糖含量15%～20%,菊苣经加工提炼果聚糖可制为菊粉。目前,在新疆几乎没有种植,为探索菊苣在我区种植前景,昌吉市农业技术推广中心在试验基地选择具有代表性的地块开展菊苣试种工作,为菊苣在我区的种植和发展提供依据。     

Cloning and Characterization of Genes Coding for Fructan Biosynthesis Enzymes （FBEs）in Triticeae Plants

Fructan is not only a carbon source for storage but also plays an important role as anti-stress agents in many plant species. Complex fructans having both β-（2,1）- and β-（2,6）-linked fructosyl units accumulate in Triticeae plants commonly. Three enzymes （sucrose： sucrose 1-fructosyltransferase, 1-SST, EC： 2.4.1.99; sucrose： fructan 6-fructosyltransferase, 6- SFT, EC： 2.4.1.10; and fructan： fructan 1-fructosyltransferase, 1-FFT, EC： 2.4.1.100） were involved in fructan biosynthesis in Triticeae plant species. We successfully isolated these genes from tetraploid wheat （Triticum turgidum, genotype： AABB）, common wheat （Triticum aestivum L., genotype： AABBDD） and three wild relatives of common wheat, Triticum urartu Thum. （the origin of the AA genome）, Aegilops speltoides （Tausch） Gren. （the putative source of the SS genome） and Aegilops tauschii Coss. （the source of the DD genome）. Sequence analysis revealed that all the FBEs （fructan biosynthetic enzymes） had three highly conserved functional motifs except 1-SST （EU981912） from tetraploid wheat species only with conserved DPNG. Low pI （isoelectric point） and potential N-glycosylation sites were predicted, which were crucial for protein compartmentation and post-translational process. Analysis on subcelluar localization signals showed that only 6-SFT had vacuolar-directed signal. Sequences alignment result showed that 1-SST and 1-FFT were more conservative and had closer relationship each other, while 6-SFT was more active during the evolution processing. According to the syntenic relationship between wheat and rice genome, FBEs were predicated to be located on the homeologous group 6 and group 2 chromosomes. Expression profile confirmed that expression of all the three FBEs were drought-stress induced. This study can assist to establish a useful theoretical platform for cold- or drought-tolerant improvement of wheat by modulating FBEs expression.     

果聚糖和甘露寡糖对幼貂生长性能的影响

为了探讨寡聚糖在毛皮动物饲料中替代抗生素的可能,随机选择体质量、性别、胎次相同的断乳幼貂80只,随机分为8组,每组10只。对照设为两组,一组饲喂基础日粮,另一组饲喂抗生素,抗生素组在基础日粮的基础上添加兽用土霉素,试验组在基础日粮上分别添加2.5、5.0和10 g/kg果聚糖和甘露寡糖。在2006-06-01-2006-07-20进行饲养试验和营养物质消化率的试验。结果表明,在饲料中添加2.5~5.0 g/kg的果聚糖和甘露寡糖能够提高水貂的采食量,提高各种营养物质的消化率和生长发育速度,效果显著(P0.05);从果聚糖和甘露寡糖提高水貂采食量、提高各种营养物质的消化率和水貂的生长发育速度方面看,果聚糖和甘露寡糖可以替代抗生素。     

不同海拔梯度对菊芋果聚糖代谢的影响

[目的]研究不同海拔梯度下菊芋各器官的果聚糖代谢特点。[方法]以青芋2号、青芋3号菊芋为试验材料,研究在不同海拔梯度下菊芋各器官中果聚糖的代谢。[结果]随着海拔高度的增加,菊芋各器官果聚糖总含量减少,地上部植株果聚糖聚合度（DP）降低、块茎内果聚糖积累总量和自地上部植株向地下部块茎转移分配率减少。海拔在2 600 m及以下,随海拔的升高菊芋块茎果聚糖聚合度降低,地上部植株果聚糖积累量降低;海拔在2 900 m以上,菊芋块茎果聚糖聚合度高、地上部植株果聚糖积累量高。[结论]该研究为拓展菊芋的种植区域和促进菊芋资源的开发利用提供了参考。     

Ta6-SFT基因对油菜的转化及抗旱性分析

为了研究Ta6-SFT对油菜抗旱的影响,进行了Ta6-SFT对油菜纯系材料的遗传转化,获得经PCR、Southern杂交和Northern 斑点杂交验证的转基因植株。对7株T₁代转基因油菜进行了为期36 d的干旱胁迫,分析干旱胁迫36 d和复水后2 d各植株及野生型对照中的Ta6-SFT的转录水平表达和果聚糖含量,同时进行同时期丙二醛含量和相对电导率测定。结果表明,Ta6-SFT的转录水平表达与转基因植株体内的果聚糖含量、转基因植株的抗旱性呈正相关,表明Ta6-SFT在干旱胁迫下的表达增强了转基因植株的抗旱性。     

添加谷物与果聚糖发酵乳工艺的优化研究

[目的]后疫情时代,消费者对饮食的需求趋于健康化,口感丰富饱满且对健康有益的产品供不应求,在此基础上,开展了在发酵乳中添加谷物、果聚糖等营养物质的产品研究。[方法]以燕麦、菊粉、发酵剂、发酵时间为主要研究对象,采用单因素及正交试验方法,对燕麦菊粉风味发酵乳进行理化及质构分析,并对发酵乳进行微生物检测。[结果]以生牛乳为主要原料,按8%的比例加入燕麦浆,4%的比例加入菊粉,0.3%的比例加入发酵剂,经过5.5 h的发酵,所得产品感官评分为92.7分。其中,4个因子对乳制品感官质量有显著改善作用,排序为：菌种数影响>发酵期影响>谷物浆浓度影响>果聚糖含量影响。产品指标及感官风味方面,添加谷物与果聚糖的发酵乳产品理化指标符合《GB19302—2010食品安全国家标准发酵乳》要求,质构稳定,持水性好,味道酸、甜味平衡,有淡淡的谷物香气。     

Optimizing Conditions Analysis of Levan by Whole-cell Biocatalysis with Corynebacterium glutamicum

This experiment was aimed to explore a new way for microbial synthesis of Levan and optimize its synthesis conditions.Levan synthesis by whole-cell catalysis using recombinant Corynebacterium glutamicum that transferred into levansucrase,and the response surface method were used to optimize the synthesis conditions with Levan yield as the response value.Firstly,the Plackett-Burman design was used to screen out three main factors affecting yield (sucrose concentration,final concentration of ethanol in Levan extraction and Ca²⁺ concentration) from 7 related factors (sucrose concentration,bacterial concentration,transformation time,transformation pH,Ca²⁺ and Mg²⁺ concentration in PBS,and final concentration of ethanol in Levan fructan extraction).Then the three most important factors selected were used for the steepest climbing test to approach the region of maximum response value,and finally use the BBD response surface method to determine the interaction between the three main factors and the best synthesis conditions.The results showed that the average yield of Levan was 0.069 g/mL in the initial experiment.The response surface method was used to optimize the whole-cell biocatalysis of Levan by Corynebacterium glutamate.The most influential factor was sucrose concentration,the second was the final concentration of ethanol,and the last was the Ca²⁺ concentration in the transformation solution.When the sucrose concentration was 52.71%,the final ethanol concentration was 85.31%,and the Ca²⁺ concentration was 0.04 g/L,the average yield of Levan synthesized by recombination Corynebacterium glutamate was 0.238 g/mL,which was close to the model's predicted maximum value of 0.233 g/mL,and the conversion rate was about 44%.The conversion rate was 1.9 times higher than the initial test,and the yield was 3.4 times higher than the initial test.The results provided the basis for Levan industrial production,and laid the foundation for its research in animal medicine and nutrition.     

转果聚糖蔗糖转移酶基因银腺杨的获得

采用农杆菌介导的遗传转化方法,将来自枯草杆菌的果聚糖蔗糖转移酶基因(SacB)导入银腺杨,以提高杨树对水分胁迫的抗性。以来自无菌培养的叶片为外植体,通过大约10 0 0个叶盘与农杆菌LBA4 4 0 4共培养,将植物双元表达载体pKP中SacB基因导入银腺杨基因组,经卡那霉素筛选后,共获得10 2株卡那霉素抗性植株。经PCR特异性扩增和Southern点杂交分析,证明其中97株再生植株基因组DNA中整合了SacB基因。对其中的6 2个无性系进行RT PCR分析,结果表明SacB基因在其中的5 0个无性系中获得表达。温室生长观察表明,转基因无性系外部形态与对照相比没有稳定的显著差异,少数部分转基因无性系的生长明显受到抑制,其他转基因无性系生长正常。这些转基因无性系的获得为培育抗旱转基因杨树奠定了基础。