Response Surface Optimization of Ultrasound-assisted Aqueous Two-phase Extraction of Sweet Potato Leaf Polysaccharides

[Objectives]The ultrasound-assisted aqueous two-phase extraction of sweet potato leaf polysaccharides was studied.[Methods]With the yield of sweet potato leaf polysaccharides as the index,the aqueous two-phase extraction system was determined,and the optimal extraction conditions were optimized by single-factor experiments and response surface methodology.[Results]The optimal parameters were ethanol concentration 25.68%,liquid-to-material ratio 55.83,and ultrasonic treatment time 38.33 min.Under these conditions,the yield of sweet potato leaf polysaccharides could reach 20.646 mg/g.[Conclusions]The ethanol/ammonium sulfate aqueous system is a rapid and efficient method for extracting sweet potato leaf polysaccharides,which is of great significance for the application of sweet potato leaf extract as a natural food additive.

Sweet Potato Leaf Curl Virus: Coat Protein Gene Expression in <i>Escherichia coli</i>and Product Identification by Mass Spectrometry

Sweet potato is one of the first natural GMOs, genetically modified 8000 years ago by Agrobacterium rhizogenes as reported recently by Kyndt et al. A section of 10 kbp long DNA (Transferred- DNA or T-DNA) of the Ri (Root-inducing) plasmid was transferred to the plant genome by A. rhizo-genes and has been maintained in all 291 hexaploid sweet potato cultivars of the world. The maintenance in the sweet potato genome and expression of two T-DNA genes for tryptophan-2-monooxygenease (iaaM) and for indole-3-acetamide hydrolase (iaaH) are likely to be physiologically significant since these enzymes convert tryptophan to indole-3-acetic acid, a major plant growth hormone auxin. Sweet potato (Ipomoea batatas (L.) Lam) is ranked the third most important root crop after potato and cassava, and the seventh in global food crop production with more than 126 million metric tons. Although sweet potato originated in Central or South America, China currently produces over 86% of world production with 109 million metric tons. In the United States, North Carolina is the leading producer with 38.5% of the 2007 sweet potato production, followed by California, Mississippi, and Louisiana with 23%, 19%, and 15.9%, respectively. Leaf curl virus diseases have been reported in sweet potato throughout the world. One of the causal agents is Sweet potato leaf curl virus (SPLCV) belonging to the genus Begomovirus (family Geminiviridae). Although SPLCV does not cause symptoms on Beauregard, one of the most predominant sweet potato cultivars in the US, it can reduce the yield up to 26%. Serological detection of SPLCV is not currently available due to the difficulties in obtaining purified virions that can be used as antigen for antiserum production. In attempts to obtain the coat protein (CP) of SPLCV for antibody production, primers were designed to amplify the CP gene. This gene was cloned into the expression vector pMAL-c2E as a fusion protein with maltose-binding protein, and transformed into Escherichia coli strain XL1-Blue. After gene induction, a fusion protein of 72 kDa was purified by amylose affinity chromatography. The yield of the purified fusion protein was approximately 200 μg/liter of bacterial culture. Digestion with enterokinase cleaved the fusion protein into a 42.5 kDa maltosebinding protein and a 29.4 kDa protein. The latter protein was identified by mass spectrometry analysis as the coat protein of SPLCV based on the fact that the mass spectrometry elucidated the sequences corresponding to 37% of amino acid positions of the SPLCV coat protein.

Postharvest Quality and Physiological Behavior of Sweet Potato (Ipomoea batatas Lam.) Leaf Stalks Under Three Temperatures

Sweet potato （Ipomoea batatas Lam.） leaf stalks were cut into 20 cm length, and stored at 20, 6, and 2℃. The respiration rate, ethylene production, ascorbic acid, free amino acid, total chlorophyll content, freshness, and shelf life were determined during storage to investigate the effect of storage temperatures on the quality and physiological responses in sweet potato leaf stalks. Wound responses were observed as high respiration rate and ethylene production immediately after cutting. Sweet potato leaf stalks were found to be sensitive to chilling injury manifested as browning and water-soaking on the surface at 2℃. In contrast, sweet potato leaf stalks were susceptible to senescence, exhibited by etiolating and yellowing, at 20℃. Loss in weight and chlorophyll was minimized under low temperatures. High temperatures also caused the accumulation of amino acids with a significant loss of ascorbic acid and chlorophyll. Sweet potato leaf stalks had a storage life of 16 days at 6℃, 8 days at 2℃, and 6 days at 20℃, respectively.

Effects of different LEDs light spectrum on the growth,leaf anatomy,and chloroplast ultrastructure of potato plantlets in vitro and minituber production after transplanting in the greenhouse

Light spectrum plays an important role in regulating the growth and development of in vitro cultured potato(Solanum tuberosum L.) plantlets. The status of potato plantlets at the end of in vitro stage influences the minituber production after transplanting. With 100 μmol m^-2s^-1 total photosynthetic photon flux density(PPFD), a light spectrum study of 100% red light emitting diodes(LEDs) light spectrum(RR), 100% blue LEDs light spectrum(BB), 65% red+35% blue LEDs light spectrum(RB), and 45% red+35% blue+20% green LEDs light spectrum(RBG) providing illumination at the in vitro cultured stage of potato plantlets for 4 weeks using fluorescent lamp as control(CK) was performed to investigate the effects of LEDs light spectrum on the growth, leaf anatomy, and chloroplast ultrastructure of potato plantlets in vitro as well as the minituber yield after 2 months transplanting in the greenhouse. Compared to CK, RB and RBG promoted the growth of potato plantlets in vitro with increased stem diameter, plantlet fresh weight, plantlet dry weight, and health index. Furthermore, BB induced the greatest stem diameter as well as the highest health index in potato plantlets in vitro. Root activity, soluble protein, and free amino acid were also significantly enhanced by BB, whereas carbohydrates were improved by RR. In addition, thickness of leaf, palisade parenchyma and spongy parenchyma was significantly increased by BB and RBG. Chloroplasts under BB and RBG showed well-developed grana thylakoid and stroma thylakoid. Unexpectedly, distinct upper epidermis with greatest thickness was induced and palisade parenchyma and spongy parenchyma were arranged neatly in RR. After transplanting in the greenhouse for 2 months, potato plantlets in vitro from BB, RB, and RBG produced high percentage of large size tuber. BB improved fresh and dry weights of the biggest tuber but decreased tuber number per plantlet. In addition, RBG increased tuber number as well as tuber fresh and dry weight slightly. Our results suggested monochromatic blue LEDs as well as combined red, blue or/and green LEDs light spectrum were superior to fluorescent lamp spectrum in micro-propagation of potato plantlets. Therefore, the application of RBG was suitable;BB and RB could be used as alternatives.

不同富硒方式对甘薯叶蛋白抗氧化活性的影响

以甘薯叶为研究对象,分别对叶面与土壤进行富硒处理,通过分析甘薯叶中硒含量及甘薯叶蛋白的抗氧化活性的变化,研究不同富硒方式对甘薯叶蛋白抗氧化活性的影响。结果显示叶面富硒与土壤富硒都能提高甘薯叶蛋白的硒含量,在1.6 mg/mL的富硒质量浓度条件下两种富硒处理组蛋白硒含量分别达到了20.10 mg/g与1.68 mg/g。富硒对甘薯叶蛋白的抗氧化活性有一定的提升作用,其中,叶面富硒可使甘薯叶蛋白超氧阴离子自由基清除率提升19.17%。根据相关性分析可知,除硒含量对抗氧化活性有较大影响外,样品中总酚与总黄酮含量也在一定程度上影响着样品的抗氧化活性。经对比可知,叶面富硒能更好地提高甘薯叶蛋白中的硒含量,是较佳的富硒方式。

马铃薯茎叶还田对土壤理化性质及细菌群落结构的影响

【目的】探究马铃薯茎叶还田对土壤理化性质和细菌群落结构的影响。【方法】基于土壤理化分析和Illumina高通量测序技术,对比分析马铃薯茎叶还田(处理组R)与不还田(处理组NR)土壤理化指标和细菌群落结构的差异。【结果】与处理CK相比,马铃薯茎叶还田提高土壤pH及有机质、碱解氮、有效磷、速效钾含量,其中速效钾含量增幅最大,达42.36~141.53 mg/kg。马铃薯茎叶还田显著影响土壤细菌群落结构,在第45、90天时,还田处理土壤中12个细菌类群丰度显著提高,且还田处理较不还田处理土壤细菌群落的物种多样性显著提高。各处理土壤细菌群落的种间互作关系主要发生在酸杆菌门、放线菌门(Actinobacteriota)和变形菌门,且马铃薯茎叶还田处理较不还田处理,土壤细菌群落种间互作强度显著提高。相关性分析表明,Latescibacterota、脱硫菌门(Desulfobacterota)与有效磷含量呈极显著负相关,与碱解氮、有机质含量呈显著正相关;粘球菌门(Myxococcota)、Bdellovibrion⁃ota、髌骨菌门(Patescibacteria)、肠杆菌门(Entotheonellaeota)、芽单胞菌门(Gemmatimonadota)、硝化螺旋菌门(Nitrospirota)、变形菌门(Proteobacteria)与速效钾含量呈显著正相关。【结论】马铃薯茎叶还田处理可以提高土壤养分含量,显著提高土壤细菌群落的物种多样性及群落物种互作强度,土壤速效钾、有效磷、碱解氮及有机质含量等理化指标与土壤细菌群落物种组成存在显著的相关关系。

基于图像测算马铃薯叶面积的校正系数

在科研和生产过程中,马铃薯叶面积测定一直存在操作难度大、误差大、工作量大等问题。校正系数法是一种简便且成本较低的叶面积估测方法,获取准确的校正系数至关重要。为探索马铃薯叶面积校正系数的准确性,以‘北方009’‘大西洋’‘冀张薯12号’‘北方002’‘希森6号’为试验材料,采用数码相机拍摄技术结合图像处理技术与马铃薯叶片长宽进行相关计算得出准确校正系数。以图像处理法获得精确的马铃薯叶片面积为参照,采用各叶片长宽乘积估算叶面积校正系数(K值),采用对各叶片校正系数简单算术平均数法估算,叶面积校正系数为0.583;采用加权算术平均数法估算,叶面积校正系数为0.585;以线性回归法求得的马铃薯叶面积校正系数为0.571。试验结果比较表明,以线性回归分析获得马铃薯叶面积校正系数(K值)0.571作为系数法参数,相关系数吻合度较高,其可作为马铃薯叶面积校正系数,应用于马铃薯科学研究与生产实践。

甘薯叶粉添加量对面包品质、抗氧化性及淀粉消化性的影响

以不同添加量甘薯叶粉面包为研究对象,通过面包基本指标的测定以及感官评定研究甘薯叶粉对面包品质的影响,并通过体外实验来分析甘薯叶粉对面包的抗氧化和体外消化特性的影响。结果表明,与对照面包相比,甘薯叶面包的比容下降、水分含量增加、色泽变暗。添加量为0.5%和1%时,面包的质构特性无显著差异,感官评价总分高于对照面包。且随着甘薯叶粉添加量的增加,面包的总酚含量(0.67~3.10 mg GAE/g)、DPPH自由基清除能力(24.15%~67.47%)和抗性淀粉相对含量(6.48%~27.47%)显著增大。综上,添加甘薯叶粉,可以提高面包的抗氧化性及抗消化性,研究结果为甘薯叶在面包类焙烤食品中的应用提供了参考依据。

基于分层特征对齐网络的小样本马铃薯病害叶片检测

针对传统马铃薯病害叶片检测方法过度依赖大量训练数据以及对未知病害识别泛化性不强的问题,提出一种基于分层特征对齐网络的小样本马铃薯病害叶片检测模型。首先,收集并整理包含多种病害类型的弱标注马铃薯病害叶片数据集。其次,在支持分支中建立文本语义和视觉语义的多模态双层特征语义表示,并利用预训练网络生成多个候选框。再次,利用卷积神经网络将候选框区域映射到深度特征空间,并借助无参数的度量方法实现文本语义与视觉语义的特征对齐。最后,将查询分支中的未知类病害图片与多模态视觉和文本语义关联集进行度量计算,根据相似度值快速给出待测图片中未知新类的病害类别。通过在自建的马铃薯病害叶片数据集和开源数据集上进行测试,所提出模型分别可以实现93.55%和96.35%的识别精度,在跨域数据集上可以实现95.15%和94.06%的识别精度,优于当前经典的目标检测模型,具有一定的实际应用价值。

基质土壤与氮钾配合施用对菜用甘薯品质的影响

探究不同基质土壤中追施不同氮钾肥对菜用甘薯茎尖品质的影响,采用盆栽试验,以湖北主栽菜用甘薯“鄂菜薯10号”为供试材料,在泥炭土、有机基质栽培土、田间土中追施不同氮钾肥处理,测定菜用甘薯在不同处理下可溶性总糖、蔗糖、硝酸盐、总黄酮、总酚等品质指标.结果表明:增施氮肥降低了菜用甘薯茎尖总酚、总黄酮、绿原酸质量分数,提高了蔗糖和硝酸盐质量分数;钾肥降低了可溶性总糖质量分数;3种基质土壤类型对菜用甘薯硝酸盐呈显著正相关性.综合而言,3种基质土壤中田间土种植菜用甘薯总糖和多酚类物质积累最多,泥炭土中氮、钾肥追施量分别为3.22 g/m 2,0.69 g/m 2,有机基质栽培土每次追施钾肥0.69 g/m 2,田间土不施肥时可溶性总糖、蔗糖、总黄酮、总酚、绿原酸等积累效果最佳.

基于位置编码和BAM注意力机制的马铃薯叶部病害识别方法

马铃薯叶部病害的准确检测和识别对于精准防治病虫害至关重要,能够有效提高马铃薯产量,但由于马铃薯叶部的早疫病和晚疫病在早期表现上非常相似,很难区分。为了更准确地对马铃薯叶部病害进行检测识别,本文提出了一种基于位置编码和并行注意力机制的Conv Ne Xt模型。首先对数据集进行位置编码预处理,使网络模型无需加载预训练权重即可获取病害部位的位置信息,提高学习能力;其次针对不同病害空间分布位置不同以及形态特征的细微差异,添加并行注意力机制BAM模块增强对病害特征的提取能力。实验结果表明:优化后的ConvNeXt模型能够准确检测并对不同病害进行分类识别,较原ConvNeXt模型Top-1准确率最高提高约5个百分点,能够满足目前马铃薯叶部病害准确识别方面的需求,有良好的鲁棒性,可以泛化在其他植物种类上。

红薯叶黄酮超声提取工艺优化、抗氧化及抑菌研究

以红薯叶为原料,采用超声辅助提取,以单因素实验为基础,结合响应面法优化红薯叶中黄酮提取工艺参数,并测定其体外抗氧化活性及抑菌作用。结果表明,红薯叶黄酮超声提取最佳条件为:料液比1∶19,超声温度42℃,提取时间42 min,乙醇体积分数58%,红薯叶总黄酮提取率为2.611%±0.032%;红薯叶黄酮提取物具有一定的抗氧化性及抑菌作用,对DPPH和ABTS自由基清除率的IC_(50)分别为0.3382 mg/mL和0.4538 mg/mL;对金黄色葡萄球菌和大肠杆菌的MIC分别为0.084 mg/mL和0.168 mg/mL。

硫酸钠-聚乙二醇双水相法萃取红薯叶多糖

以红薯叶为原料,采用超声辅助硫酸钠-聚乙二醇双水相法提取红薯叶中多糖。以多糖萃取率为考核指标,在单因素试验的基础上,通过正交试验优化提取工艺。结果表明:最佳工艺条件为料液比1∶20(g/mL)、pH 5、超声时间30 min、超声温度60℃,该条件下红薯叶多糖的平均萃取率为94.2%,得率为62.6 mg/g。

响应面法优化红薯叶凉粉的配方及工艺

为研究红薯叶提取液对凉粉产品综合品质的影响,本文以红薯叶及红薯淀粉为主要原料,考察碳酸钠添加量、白砂糖添加量、红薯叶提取液添加量、红薯淀粉添加量、蒸制时间等因素对红薯叶凉粉感官品质和质构特性的影响,在此基础上,以弹性为响应值做响应面优化试验,确定红薯叶凉粉的最优配方及工艺参数。结果表明,采用浓度为0.20 g/100 mL的碳酸钠溶液制备红薯叶提取液效果较为理想。红薯叶凉粉最佳配方为:红薯叶提取液40 mL/100 g、白砂糖1 g/100 g、红薯淀粉19 g/100 g,纯净水40 mL/100 g。原料经充分混合并蒸制处理8 min,再经冷却制得的红薯叶凉粉色泽翠绿,质地均匀,具有红薯叶特有香气,经验证弹性为6.19。本研究为进一步拓展红薯叶应用范围,提升红薯产业综合附加值提供了技术支持。

甘薯曲叶病毒PCR-层析试纸条快速检测方法的建立

为了能够快速且同时大批量检测甘薯样本是否感染甘薯曲叶病毒(SPLCV),本研究建立了SPLCV cp基因的PCR-层析试纸条快速检测方法。首先,本研究构建SPLCV cp基因的重组质粒作为阳性对照,并对标记的特异性引物的扩增条件进行优化。结果显示,退火温度为57℃时,特异性扩增效果最佳;特异性检测结果表明,该引物对与甘薯无症状1号病毒(SPSMV-1)、甘薯杆状DNA病毒B(SPBV-B)、甘薯羽状斑驳病毒(SPFMV)、甘薯褪绿矮化病毒(SPCSV)和甘薯潜隐病毒(SPLV)均无交叉反应,表明该引物对具有较高的特异性。其次,本研究构建了PCR-层析试纸条快速检测系统,当抗体包被磁粒时,20μg地高辛单克隆抗体为0.1 mg羧基磁粒的最佳抗体标记量。特异性扩增产物在新构建的层析系统中3 min左右进行可视化检测;灵敏度检测结果表明,该层析系统的最低检测限为0.0001 ng·μL^(-1)基因组DNA,灵敏度是普通凝胶检测的10倍,说明该系统灵敏度较高。综上,本研究建立的PCR-层析试纸条检测系统具有可视性、灵敏度高、简便快速的特点,且可以同时对大批量的样本进行SPLCV检验,满足了脱毒薯苗上市前检测量大的需求。

核桃根和叶水浸提液对土豆的化感效应研究

为探讨核桃林下种植土豆的合理性,本文研究了核桃根、叶水浸提液与土豆之间的化感效应。结果表明:不同浓度核桃根、叶水浸提液对土豆出苗率无影响,中等浓度核桃根和叶水浸提液对土豆地上部分生长都有明显的抑制作用,高浓度的核桃叶水浸提液和低浓度的核桃根水浸提液均对土豆地上部分生长有促进作用。低浓度核桃叶水浸提液能促进土豆块茎生长,高浓度核桃叶水浸提液会抑制土豆块茎生长,表现出“低促高抑”的双重浓度效应。低浓度核桃根水浸提液对土豆块茎生长无影响,高浓度核桃根水浸提液能促进土豆块茎生长。

基于冠层光谱和覆盖度的马铃薯叶片钾含量估算方法

叶片钾含量(Leaf potassium content, LKC)是表征作物钾素营养状况的重要指标,高效准确地获取马铃薯LKC有助于精准农业施肥管理。本研究旨在通过结合马铃薯关键生育期RGB影像提取的植被指数(VIs)和植被覆盖度(FVC),提高马铃薯关键生育期LKC估算的准确性。首先从马铃薯块茎形成期(S1)、块茎增长期(S2)和淀粉积累期(S3)的RGB影像中提取VIs和FVC,然后分别分析每个生育期VIs和FVC与马铃薯LKC的相关性,最后利用支持向量机(Support vector machine, SVM)、Lasso回归(Least absolute shrinkage and selection operator, Lasso)和岭回归构建马铃薯LKC的估算模型。结果表明:基于RGB影像提取的马铃薯FVC精度较高,且前两个生育期高于第3个生育期;利用VIs估算马铃薯LKC是可行的,但精度有待进一步提高;VIs结合FVC可以提高马铃薯LKC的估算精度。本研究可为作物生长和钾素营养状况监测提供技术参考。

响应面法优化红薯叶中水溶性膳食纤维提取工艺

采取微波萃取法提取红薯叶中水溶性膳食纤维(SDF),以SDF得率为评价指标,在单因素试验的基础上通过响应面法优化提取工艺。结果表明:最佳提取工艺为柠檬酸质量分数7%、微波功率为中低火、微波时间58 s,在此条件下红薯叶中SDF得率为26.46%±0.15%。

叶菜型甘薯资源耐寒性评价体系研究

【目的】比较不同叶菜型甘薯品种的耐寒性,找出能科学评价品种耐寒性的指标,建立可靠的耐寒性数学评价模型,筛选耐寒性强的叶菜型甘薯品种,为耐寒资源鉴定与筛选提供理论依据和参考。【方法】以13个叶菜型甘薯品种为材料,设置25℃为对照温度,10℃为低温胁迫温度,研究叶片中过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)、可溶性蛋白(SP)、可溶性糖(SS)、组织含水率(TMC)、叶绿素(Chl)、类胡萝卜素(Car)及叶绿素a/b(Chl a/b)10个指标对低温胁迫的响应。以各单项指标的耐寒系数为衡量依据,运用主成分分析、聚类分析和逐步回归等方法进行耐寒性综合评价。【结果】通过主成分分析将10个单项生理指标转换为4个相互独立的综合指标;13个叶菜型甘薯品种按照耐寒性强弱划分为4类,即不耐寒型、轻度耐寒型、中度耐寒型、高度耐寒型;建立叶菜型甘薯耐寒性评价数学模型,D=0.283+0.0171X_(1)-0.074X_(3)+0.166X_(4)+0.409X_(5)-0.874X_(7)-0.067X_(8)+0.116X_(9)+0.030X_(10),估计精度大于95%;筛选出8个耐寒性鉴定指标,即POD、CAT、SOD、SP、TMC、Chl、Car及Chl a/b。【结论】低温胁迫条件下,不同叶菜型甘薯品种发生不同程度的生理变化。通过回归方程筛选获得的8个关键指标可用于叶菜型甘薯品种的耐寒性鉴定和预测。结合隶属函数综合评价模型得出,供试13个叶菜型甘薯品种中耐寒性最强的前3名为:福菜薯18、渝菜薯3号、广菜薯6号,可在早春推广种植耐寒能力强的品种,结合现代保温设施,使其提早上市从而抢占市场。

耐热甘薯品种筛选及生理机理探析

为了筛选获得甘薯耐热品种,以4个优质甘薯品种为研究对象,将叶片耐热评价值、SPAD值、过氧化氢(H_(2)O_(2))含量、丙二醛(MDA)含量、过氧化氢酶(CAT)活性以及抗坏血酸过氧化物酶(APX)活性作为耐热指标,对比35℃和40℃高温胁迫下4个品种甘薯叶片各指标间的差异,探究高温胁迫对甘薯叶片生理及抗氧化酶活性的影响。结果表明:35℃高温胁迫下,4个品种甘薯叶片形态无明显变化,在40℃高温胁迫下,龙薯116和莆薯23的叶片出现明显的失水卷曲,SPAD值较金山57和广薯87显著降低;叶片中产生的H_(2)O_(2)含量高达2.53μmol·g^(-1)和4.21μmol·g^(-1),造成CAT以及APX的活性增强,且MDA含量较金山57和广薯87显著增加,高达10.06 nmol·g^(-1)和14.94 nmol·g^(-1)。综合评价,参试品种中广薯87为耐热性优秀的甘薯品种,金山57次之。研究结果可为甘薯种植产业提供耐热品种资源,为甘薯耐热品种的选育提供理论依据。