Rapid detection of potato late blight using a loop-mediated isothermal amplification assay

Potato late blight caused by Phytophthora infestans is one of the most destructive plant diseases that threaten global food security. Early and effective diagnosis of P. infestans is required before disease management decisions are made. Here, we developed a quick protocol to detect P. infestans based on a loop-mediated isothermal amplification(LAMP) assay. The P. infestans specific multiple copy DNA sequences(PiSMC), a transposon-like element, provides an ideal target for molecular detection of this pathogen. We designed highly specific and sensitive primers allowing effective LAMP detection of the pathogen at 64℃ in 70 min. In the validation assay, all 15 P. infestans isolates collected from China, Europe and South America could be positively detected, but results of the other 9 Phytophthora species infecting different plants, fungal and bacterial plant pathogens tested were negative. The detection limit of this assay is 1 pg P. infestans DNA. Moreover, the LAMP-PiSMC assay is able to detect P. infestans from infected leaves, tubers and soil. Taken together, this study reports the development of a specific and sensitive LAMP-PiSMC assay for early diagnosis of potato late blight.

Inhibitory effect of tartary buckwheat seedling extracts and associated flavonoid compounds on the polyphenol oxidase activity in potatoes(Solanum tuberosum L.)

To improve the processing quality of potatoes,phosphate buffer extract(PBE),50%ethanol(E50),and aqueous extract(AE)of tartary buckwheat seedlings were evaluated for their ability to inhibit the enzymatic browning of potatoes.The results suggest that all extracts of tartary buckwheat seedlings exert significant inhibitory effects on the polyphenol oxidase(PPO)activity in potatoes.The relative concentrations required for a 50%reduction in the PPO activity(IC50)were 0.21,0.28 and 0.41 mg mL^-1,for PBE,E50 and AE,respectively.The strongest inhibitory activity was observed for PBE,followed by E50 and AE.Four flavone compounds in the PBE of tartary buckwheat seedlings(i.e.,rutin,kaempferol-3-O-rutinoside,quercetin,and kaempferol)were identified by high-performance liquid chromatography.These compounds were subsequently evaluated for their roles in the inhibition of PPO from potatoes using a model system.The results indicated that rutin exhibited the highest inhibition rate on the PPO of potato.A synergistic inhibitory effect was observed by mixing rutin,kaempferol-3-Orutinoside,quercetin,and proteins.The inhibitory patterns of rutin,kaempferol-3-O-rutinoside,and quercetin on the enzyme were noncompetitive and reversible,with inhibitory constants of 0.12,0.31,and 0.40 mg mL^-1,respectively.Flavonoids from tartary buckwheat seedlings may exhibit a common mechanism with phenolic compounds,involving the blockage of the reaction of oxygen with PPO leading to the inhibition of the enzymes involved in browning.Based on these results,extracts of tartary buckwheat seedlings can be used as potent natural inhibitors.

Impact of Plant Density on the Formation of Potato Mimitubers Derived from Microtubers and Tip-Cuttings in Plastic Houses

The potato minitubers have been widely used for the elite seed propagation to improve the seed potato system in China. However, little information is available for an efficient production of the minitubers with high plant density in the protected growing conditions like plastic houses. In present research, the minitubers of a wide-grown potato variety, Favorita, were produced with the microtubers from tissue culture and the tip-cuttings of the microtuber plants. Three plant densities, 200, 400 and 600 microtubers or plants m-2 were set up with the randomized block design of 3 replications and the experiment was repeated in 4 seasons in 2009-2010. The canopy development, light interception, dry weight production and partitioning, tuberization and tuber weight were investigated to elucidate the mechanism by which the plant density affects the formation and growth of the minitubers. The results showed that the number of the tubers formed per unite area was in line with the increase in plant density. The difference in leaf area index （LAI） between the plant densities, especially in early stage of the plant growth, resulted in more radiation interception and dry weight producing in higher plant density than in lower one. However, our analysis demonstrated that the conversion coefficient of the cumulative intercepted radiation to plant weight and the dry weight partition rate to the tubers were constant between plant densities, suggesting that less amount of the photoassimilates partitioned to individual tubers is causal for more small tubers in high plant density. A negative exponential curve model, determined by total number of tubers produced per unit area and the mean tuber weight, fitted well to the tuber size distribution pattern. The optimum plant density could be estimated from this model for a maximum production of the minitubers with desired size.

Pesticides Could Alleviate the Symptoms of Sweet Potato Virus Disease(SPVD)

In recent years, sweet potato virus disease （SPVD） has severely affected the production of sweet potato in China. In order to select chemical agents to prevent sweet potato from being infected with SPVD, 14 pesticides were sprayed on the plants of sweet potato infected with SPVD, and the relative mRNA level of the viruses in the leaves and physiological indicators of sweet potato plants were detected. The results showed that after the application of most of the pesticides, the relative mRNA level of the two viruses that caused SPVD decreased, and the chlorophyll content and biomass of sweet potato infected with SPVD increased significantly or extremely significantly. Among the pesticides, BASF virus liquid, 0.1% physcion and Aolike powder for cucumber virus were proved to be the best, as the chlorophyll content and stem length of sweet potato increased significantly. The experiment indicated that the pesticides could reduce the harm of SPVD to sweet potato.

Present Situation and Prospect of Grub Control in Sweet Potato Field

Grub is one of the major pests affecting yield and quality of sweet potato. Although traditional chemical pesticides have quick effect, the disadvantages of high toxicity, strong pest resistance, and heavy pollution hinder the development of modern ecological agriculture, while physical means such as light trapping, sex pheromone method and biological control methods are more safe and lasting compared with chemical means. To provide reference and guidance for grub control and sweet potato production, the control methods against sweet potato grubs are comprehensively explored, and strategy and prospects of using biological technology to control pests are analyzed.

Population Improvement of Resistance to Late Blight in Tetraploid Potato:A Case Study in Combination with AFLP Marker Assisted Background Selection

Cultivated potato with high level of horizontal resistance against late blight is one of the most important goals of potato breeding.The recurrent selection has been adopted to increase the level of potato horizontal resistance and a B3C1 population without R1-R11 dominant genes has been released by the International Potato Center at the short-day condition of Peru.The present research was carried out to further improve the resistance and the agronomic traits of B3C1 population under long-day condition of Hubei,China,with maximized retention of its genetic diversity.Twenty-seven individual clones of B3C1 were used to generate population B3C2 by in-population crossing with the bulk pollens aiming to elevate the frequency of late blight resistance genotypes and to improve the adaptation to local long-day conditions.The late blight resistance and the main agronomic traits including the maturity,the plant characters and the tuber traits were evaluated for the foreground selection in three years,by which 130 pedigrees were maintained as the basic population of B3C2 for further selection.A total of 312 polymorphic loci detected by 9 AFLP marker combinations were used to monitor the genetic diversity of the populations for the background selection.The B3C2 population of 51 clones was finally selected,of which the frequency of resistant genotypes increased by 23.8% points and the genetic diversity was maintained by about 96% as referred to B3C1.Our results strongly suggested that combination of the foreground selection for target traits and the background selection for the genetic diversity is an efficient strategy in the recurrent selection of tetraploid potato to improve quantitative traits.

暹罗芽胞杆菌JZ1-4-10对马铃薯干腐病的抑菌作用及机理

为了得到对马铃薯干腐病具有良好抑菌效果的生防细菌,本研究从4株芽胞杆菌中筛选出暹罗芽胞杆菌JZ1-4-10,并通过马铃薯活体试验探究菌株JZ1-4-10防治马铃薯干腐病及其相关防御酶活性的影响。结果表明,4株芽胞杆菌中菌株JZ1-4-10的抑菌活性最高,对茄病镰刀菌的抑菌率达59.15%,发酵液的抑菌率达61.25%;此外,菌株JZ1-4-10处理有效提高了马铃薯SOD和POD活性,降低PPO酶活性和MDA含量,保持了马铃薯贮藏期间的品质,且对马铃薯干腐病的预防效果优于治疗、钝化的防治效果,达85.17%;同时,该菌株菌悬液及挥发性有机物均有较高的抑菌活性,并具有较强的生物膜形成能力。因此,暹罗芽胞杆菌JZ1-4-10对马铃薯干腐病有着巨大的防治潜力,可进一步开发成生防菌剂。

恩施地区马铃薯育成品种遗传多样性分析

为明确恩施地区自主选育的16个马铃薯品种的亲缘关系及遗传多样性,本研究利用筛选的9对SSR引物,对16份恩施地区自主选育的马铃薯品种进行遗传多样性分析。结果表明,9对SSR引物共扩增出117个位点,其中114个为多态性位点,平均每对引物扩增出13个等位位点、12.67个多态性位点;16个马铃薯品种的遗传距离在0.1818~0.6867之间,平均遗传距离为0.3780;在相似系数为0.553附近,16份试验品种可分为三类,第Ⅰ类仅含1个品种(鄂马铃薯1号);第Ⅱ类包括6个品种(鄂马铃薯4号、鄂马铃薯5号、鄂马铃薯6号、鄂马铃薯15号、鄂马铃薯8号、鄂马铃薯13号);第Ⅲ类包括9个品种(鄂马铃薯2号、鄂马铃薯3号、鄂马铃薯9号、鄂马铃薯10号、鄂马铃薯7号、鄂马铃薯11号、鄂马铃薯12号、鄂马铃薯14号、鄂马铃薯16号)。研究结果为南方冬作区马铃薯育种亲本的选择和杂种优势利用提供参考。

砜嘧磺隆在土壤中的动态消解规律

“薯/玉/豆”带状复合种植技术中,由于作物栽培时间和生育期不一致导致田间杂草管理难度较大,符合该技术的除草剂鲜有报道。砜嘧磺隆杀草谱广、选择性好,可较好应用到该技术中。为准确评价砜嘧磺隆在土壤中的残留动态,明确其在“薯/玉/豆”带状复合种植技术中应用的安全性,采用室内模拟试验,应用高效液相色谱法测定砜嘧磺隆在土壤中的残留。25%砜嘧磺隆水分散粒剂在施药量为0.5~2.0 mg/kg时,在土壤中半衰期为7.70~9.50 d,9.50 d内降解量为初始沉降剂量一半,在施药42 d后土壤残留量为0.0018~0.0090 mg/kg。为确保安全使用砜嘧磺隆,最大限度减轻除草剂造成的药害,施用砜嘧磺隆9.50 d后再栽培其他作物相对安全。

施钾对马铃薯苗期抗旱性的影响

为研究不同施钾水平对马铃薯苗期抗旱性的影响,本研究以马铃薯品种大西洋为材料,对苗期不同干旱胁迫的大西洋增施不同量钾肥,测定其生长指标和生理指标,并探究在不同条件下植株的抗旱性差异。结果表明:干旱胁迫会显著抑制马铃薯株高、茎粗的生长,同时显著降低叶片叶绿素含量、叶片类胡萝卜素含量、光合生理指标及根系活力,会促使马铃薯叶片中丙二醛含量、脯氨酸含量、抗氧化物酶活性增加,进而影响马铃薯块茎的产量及品质。增施一定量的钾肥可有效缓解干旱对上述指标的影响,均在K2(180 kg/hm^(2))水平下效果最佳。在K2施钾水平下,T0、T1和T23种干旱胁迫条件下的马铃薯块茎重量较未施钾肥的分别增加了23.3%、27.8%和36.2%,块茎淀粉含量分别增加了25.2%、25.47%和33.67%,维生素C含量分别增加了34.83%、36.91%和43.05%。综上,施钾量为180 kg/hm 2对马铃薯幼苗抗旱性和生长发育的促进效果最佳。

优质鲜食型甘薯新品种‘徐薯32’的选育及特性分析

甘薯新品种‘徐薯32’是以品质性状良好的‘徐薯55-2’为母本、‘红东’为父本,经有性杂交培育而成。该品种于2015年通过河南省农作物品种审定委员会审定。通过对‘徐薯32’农艺性状特征、生产力、抗病性、品质性状等进行研究,结果表明:‘徐薯32’地上部短蔓,薯块萌芽性好,耐贮藏,熟食口感佳;抗黑斑病,中抗根腐病与茎线虫病;鲜薯产量与对照‘徐薯22’相当,薯干和淀粉产量较对照分别增产15.24%和18.99%;‘徐薯32’块根主要营养物质含量均高于‘徐薯18’,其淀粉最高粘度值与崩解值较‘徐薯18’分别高6.52%和12.40%,糊化温度则略低于‘徐薯18’;淀粉粒径表面积与体积分布呈三峰、数目分布呈单峰,三类分布中淀粉颗粒总平均粒径均低于‘徐薯18’,降低幅度分别为12.22%、13.18%和2.22%。因此,‘徐薯32’具有良好的农艺性状与品质特性,可为鲜食型甘薯品种改良和应对市场需求奠定基础。

湖南省马铃薯主产区马铃薯病毒种类及流行分析

马铃薯是世界第四大粮食作物，其病毒病危害严重。2010年对湖南马铃薯主产区采集的66个病毒标样进行了RT—PCR检测，结果表明，检测出的马铃薯病毒有马铃薯Y病毒（PYY）、马铃薯卷叶病毒（PLRv）、马铃薯x病毒（PVx）、马铃薯s病毒（PVS）、马铃薯A病毒（PVA）和马铃薯纺锤块茎类病毒（PSTVd）。其中PVS的检出率最高，为54．5％，其次是PVX，检出率为45．5％，PVY的检出率为39．4％，唧d和PVA的检出率均为21．2％，PLRV的检出率为18．2％。2～4种病毒的复合侵染现象较为普遍。PVY中重组型PVY占85．7％。

植物乳杆菌发酵苦荞芽苗茶饮料加工工艺研究

萌发后的苦荞芽苗富含黄酮等有益成分,采用植物乳杆菌对苦荞芽苗和苦荞茶汁进行发酵,通过单因素实验和响应面法确定优化的发酵工艺条件和配方,并对产品的总黄酮含量、透光率和pH值进行测定。实验结果显示,较优的苦荞芽苗与苦荞茶汁比例为1:6,较优的上清液稀释比例为1:10,产品的总黄酮含量可达(0. 193±0. 006) mg/mL。优化的发酵工艺条件为:菌剂添加量0.6%,发酵时间24 h,果葡糖浆添加量6%,该条件下感官评分的平均值达91.50±0.29,较适的pH值为3. 87±0. 05。优化的稳定剂配方为:黄原胶添加量0. 06%,羧甲基纤维素钠(CMC-Na)添加量0. 08%,海藻酸钠添加量0. 05%,该条件下感官评分的平均值达93. 60±0. 32,透光率为91. 37%±0.45%。发酵后的苦荞芽苗茶饮料富含黄酮和益生菌等有益成分,口感醇正、澄清透明、风味独特。

乳酸菌发酵对苦荞芽苗饮料品质和营养成分的影响

为确定较优的乳酸菌发酵菌种,向苦荞芽苗饮料中接种保加利亚乳杆菌、嗜热链球菌和植物乳杆菌进行发酵,比较发酵过程中饮料感官评分、乳酸菌活菌数、总糖、还原糖、总酸、总蛋白、总黄酮、芦丁、槲皮素、山奈酚-3-O-芸香糖苷等营养成分的变化。结果表明,乳酸菌能够较好地在苦荞芽苗饮料中生长,植物乳杆菌的发酵活性较其他2种乳酸菌高,且植物乳杆菌和保加利亚乳杆菌混合发酵有一定的协同作用,得到的产品感官评分最高。不同乳酸菌发酵造成饮料液中总糖和还原糖含量下降,发酵48h后总糖含量最多下降了24.8%,还原糖含量最多下降了34.2%。植物乳杆菌在发酵48h产酸量最多,嗜热链球菌产酸能力最弱。饮料液中的蛋白质被乳酸菌作为氮源利用,发酵48h后其总蛋白含量最多降低了58.6%。乳酸发酵对芦丁基本没有影响,但会造成槲皮素和山奈酚-3-O-芸香糖苷少量分解。

响应面法优化贵州特色洋芋粑加工工艺

目的 采用响应面法优化贵州特色洋芋粑加工工艺。方法 以感官评分为评价指标,优化洋芋粑厚度、预炸温度和时间、配料添加量,幵在单因素实验的基础上,通过响应面试验优化洋芋粑配斱和工艺。结果 速冻洋芋粑较优的厚度为1.00 cm,预炸温度220℃,预炸时间25 s。食盐添加量0.5%,纯净水添加量15.0%,棕榈油添加量3.0%,玉米淀粉添加量4.0%时,为最佳的速冻洋芋粑配斱,预测感官评分的理论值为100.0分,验证实验得到感官评分为(95.3±1.4)分。结论 采用优化后的工艺制得的速冻洋芋粑口感较好,食用斱便,可作为工业化生产的基本加工条件。

芦荟叶皮β-葡萄糖苷酶的分离纯化及酶学性质

库拉索芦荟叶皮经匀浆、柠檬酸-柠檬酸钠缓冲液抽提,硫酸铵分级沉淀,DEAE-Sepharose fast flow层析和Superdex-200prep grade层析,获得电泳纯的β-葡萄糖苷酶(β-Glucosidase,BGL).纯化结果是β-葡萄糖苷酶比活力为98.48U/mg,纯化倍数为328.27倍,酶活性回收率为9.87%,全酶分子质量约为69.3kD,亚基分子质量约为69.7kD.酶学性质研究表明:β-葡萄糖苷酶的最适反应温度和最适反应pH值分别为40℃和5.0;在20~30℃及pH4.0~8.0范围内稳定性较好;最适条件下,以pNPG为底物的K_m值为2.21mmol/L,V_(max)为1.381μmol/(min·L).乙醇,抗坏血酸,Mn^(2+),K^+对该酶活性具有激活作用;SDS,Cu^(2+)对该酶活性具有强烈抑制作用;异丙醇,EDTA,尿素,Mg^(2+),Li+对该酶活性影响较小;甲醇对该酶有双重作用.

基于近红外光谱技术快速检测苦荞面条中荞粉含量

以苦荞面条为研究对象,采用近红外漫反射光谱(NIR)技术结合偏最小二乘法(PLS)建立预测苦荞面条中荞粉含量的定量模型,实现荞粉含量的在线快速检测。根据参考值,制作230份苦荞面条样品,分别以移动平均平滑、一阶导数、归一化处理、标准正态化、多元散射校正等方法预处理光谱。结果表明,选择波数9403.6~7498.2,6101.9~5446.2cm^-1+一阶导数+多元散射校正(MSC)所建的模型效果最好,预处理后模型相关系数为0.9839,其交叉验证均方根误差(RMSECV)、预测标准误差(RMSEP)、预测相对分析偏差(RPD)、最低检出限(LOD)和定量检出限(LOQ)分别为1.14、0.894、7.89、2%、5%。外部验证预测相关系数为0.9852,RMSEP、RPD分别为0.881、5.41,相对标准偏差(RSD)均小于1,不同产地苦荞粉对比验证集的R2、RMSEP、RPD分别为0.9637、0.926、5.22,RSD较小,模型具有较高的精密度,符合实际生产的需求。该方法快速、低成本、准确、简便、无污染,可以实现苦荞面条中荞粉含量的快速检测。

马铃薯A病毒研究进展

马铃薯A病毒（PotatovirusA，PVA）是马铃薯生产上危害较严重的病毒之一。PVA已知的寄主为茄科植物，在马铃薯上引起的症状与气候条件、马铃薯品种和PVA的株系有关。PVA基因组与其他PVY属已知序列的病毒核苷酸序列同源性在53％～58％之间，编码的11种蛋白在基因组复制、蛋白加工、蚜虫传毒、系统移动以及与寄主组分互作等方面具有各自的功能。马铃薯对PVA的抗性分为过敏抗性（HR）和极端抗性（ER）两类，植物对PVA的抗性机制主要分为显性基因介导的抗性、隐性基因介导的抗性、RNA介导的抗性。PVA的致病机理、PVA抗性基因挖掘和抗PVA转基因新策略将是今后的研究重点。

国内育成马铃薯品种资源的表型及品质性状综合评价

在恩施种植马铃薯品种资源100份,调查及测定了36个质量性状和9个数量性状,并进行遗传多样性分析和聚类分析,为选育适宜西南山区春种马铃薯新品种及生产利用提供参考。结果表明,质量性状中托叶形状、叶表面光泽度、叶缘、顶小叶形状、柱头长短、花冠大小、茎翼形状的遗传多样性指数为3.2189~3.9120,相比其他性状遗传多样性丰富;数量性状中株高、粗蛋白含量、产量等遗传多样性指数较高,均为4.6052。供试材料的株高、主茎粗、主茎数、还原糖含量均与产量呈极显著正相关,其他性状与产量呈正相关,但未达到显著水平。聚类分析结果表明,供试资源可分为6个类群,其中以Ⅴ、Ⅵ类群马铃薯品种数量最多,Ⅲ、Ⅳ类群次之,Ⅰ、Ⅱ类群最少,仅占总数的19%;相比其他类群,Ⅰ、Ⅱ类群品种具有高产、植株高大、营养物质含量较高等特性,可作为选育西南山区春种高产优质马铃薯新品种的亲本材料。

定远县甘薯引进品种比较试验

为筛选适合定远县高产、优质的甘薯品种,2019年夏季引进9个甘薯新品种进行品种比较试验。以苏薯8号为对照,从农艺性状、产量性状和营养品质等方面进行筛选鉴定。结果表明,9个引进品种中,徐紫薯602、普薯32号、岩薯5号、安平1号、心香5个品种的产量表现优于对照品种。其中,紫心品种徐紫薯602、红心品种普薯32号和黄心品种心香分别比对照显著增产27.88%、36.55%和38.00%。这3个品种的还原糖和可溶性糖含量低于对照品种,但淀粉和蛋白质含量明显高于对照品种。综合分析试验结果,徐紫薯602、普薯32号和心香丰产性状好,蛋白质含量高,口感偏黏或粉糯,可满足不同的消费者需求,适宜在定远县推广种植。