Research Progress in Biological Control of Soft Rot of Amorphophallus konjac

In this paper,the main control methods of soft rot of Amorphophallus konjac are reviewed,with a focus on the current research status of using plant growth promoting rhizobacteria for biological control of soft rot of A.konjac,and future research directions are looked forward to.

Effects of Intercropping on Rhizosphere Soil Bacterial Communities in Amorphophallus konjac

Soft rot disease causes heavy loss in konjac production every year, which caused by the genus Pectobacterium has been recognized as a major reason why konjac industry has not boomed in worldwide. However, intercropping with economically important trees can effectively control affect soft rot disease epidemics. Consequently, we conducted a rhizosphere bacterial diversity study to assess how intercropping affects soft rot disease using next-generation DNA sequencing. The results demonstrate the Shannon diversity index and Chao 1 index for soil bacteria were relatively steady under intercropping conditions, but changed greatly for the konjac monocrop with the increase in the number of cropping years. Of the 44 bacterial genera with relative abundance ratios of >0.3%, 11 were significantly affected by the duration of continuous cropping and the cultivation mode. Luteolibacter and Bacteroides showed highly significant differences between the monocrop and the intercrop for three continuous years. Pseudomonas was significantly affected by the different cultivation modes, while Myroides was significantly affected by planting age. Intercropping altered the structure and composition of the soil bacterial community, which led to a relative balance of beneficial bacteria, and the relative balance of beneficial bacteria is helpful to reduce the incidence of soft rot.

Constitutive and Secretory Expression of the AiiA in Pichia pastoris Inhibits Amorphophallus konjac Soft Rot Disease

Amorphophallus konjac is an important economic crop widely cultivated in Southeast Asia and Africa. However, A. konjac is seriously infected by soft rot pathogen. The endocellular acyl homoserine lactonase (AiiA) which is generated by Bacillus species has inhibitory effect on soft rot pathogen through disrupting the signal molecules (N-acylhomoserine lactones, AHL) of their Quorum Sensing system. The aim of our study is to obtain recombinant yeast which produces AiiA protein. The recombinant yeast Pichia pastoris GS115 was constructed to constitutive expression of the AiiA gene. The results of reverse transcript PCR analysis showed that the AiiA gene was expressed successfully in the yeast. Proteins extracted from YPDS showed the highest inhibition efficacy to E. carotovora compared with the other two mediums (YPD and LB) under tested conditions.

Exploring the Insecticidal Potentiality of <i>Amorphophallus paeonifolius</i>Tuber Agglutinin in Hemipteran Pest Management

Hemipteran group of sap sucking insect pests cause worldwide crop destruction. The role of mannose specific monocot lectins have recently been worked out in hemipteran pest management. The present article demonstrates the insecticidal efficacy of a new mannose specific agglutinin, isolated from tubers of Amorphophallus paeonifolius (AMTL) against a wide range of hemipteran insects. The 25 kDa dimeric protein was found to inhibit the survivability of hemipteran insects namely, Lipaphis erysimi, Aphis gossypii and Dysdercus cingulatus quite efficiently, as analysed by synthetic diet based bioassay experiments. Surface Plasmon Resonance study detected binding of insecticidal AMTL to insect gut brush border membrane vesicle (BBMV) protein, an absolute prerequisite for conferring toxicity against target insects. Further ligand blot analysis spotted a ~74 kDa glycoprotein as putative receptor of AMTL from the total BBMV protein fraction of Lipaphis erysimi. Phylogenetic analysis showed a significant relatedness of AMTL to the previously established monocot lectin Galanthus nivalis agglutinin (GNA) in terms of their conserved mannose binding domains, agglutinating ability of rabbit erythrocytes and insecticidal efficacies. These information project AMTL as a promising candidate in preventing crop loss caused due to hemipteran insect attack.

Protective effect of Amorphophallus campanulatus(Roxb.) Blunie.tuber against thioacetamide induced oxidative stress in rats

Objective:To identify the phytochemical constituents of Amorphopkallus campanulatus(A. campanulatus) tuber and to evaluate its antioxidant potential through in vitro and in vivo models. Methods:Phytochemical screening and in vitro antioxidant activities of A.campanulatus tuber n-hexane extract(ACHE) and methanolic extract(ACME) were evaluated using DPPH,hydroxyl radical,reducing power and total antioxidant capacity assays.The total phenolic and flavonoid contents were also investigated.The protective potential of two different doses of ACME(125 and 250 mg/kg) was also evaluated against thioaeetamide(TAA) induced oxidative stress in rats. Silymarin used as a standard drug control.Hepatotoxicitv was assessed by quantifying the serum levels of aspartate aminotransferase(AST),alanine aminotransferase(AIT),alkaline phosphatase (ALP) and lactate dehydrogenase(LDH).The antioxidant potential of ACME were also evaluated by the estimation of catalase(CAT),glutathione peroxidase(GPx),glutathione reductase (OR),glutathione-S-transferase(GST),reduced glutathione(GSH) and lipid peroxidation (Thiobarbituric acid reactive substances) in hepatic and renal tissues.Histopathologic changes of liver were also evaluated.Results:In vitro studies revealed that ACME has higher antioxidant and radical scavenging activity than ACHE,which may be attributed to its higher phenolic and flavonoid content.ACME significandy prevented the elevation of serum AST,ALT.ALP,LDH,and tissue malondialdehyde levels(P 【 0.05).Hepatic and renal GSH.GST.GR,GPx,and catalase levels were remarkably increased by the treatment with the extract.Quantification of histopathological changes also supported the dose dependent protective effects of ACME.Conclusions:The results do suggest that A.campanulatus tuber could be considered as a potential source of natural antioxidant.

Quality Characteristics and FTIR Research of Amorphophallus konjac K. Koch Cultivated under Forest

[Objectives]This study aimed to evaluate the quality characteristics of Amorphophallus konjac K.Koch and study the tubers of A.konjac K.Koch by infrared spectroscopy and second derivative method.[Methods]Referring to industrial standards of China for agriculture and related documents,the quality characteristics of A.konjac K.Koch were determined;and using potassium bromide tableting method and Fourier transform infrared spectroscopy,the infrared spectrum and second derivative spectrum of A.konjac K.Koch were studied.[Results]The drying rate,total ash content,acid-insoluble ash content,water extract content,ethanol extract content and crude polysaccharide content of A.konjac K.Koch were above 14.00%,4.57%-11.78%,0.04%-4.87%,26.31%-36.98%,2.20%-7.95%and 40.25%-61.18%,respectively.The infrared spectra of A.konjac K.Koch of different origins were relatively close,and the differences were mainly in peak intensity.The peaks at 1642,1322,1241,1154,1022,863,770 and 576 cm-1 were the main specific peaks.The main component was konjac glucomannan.[Conclusions]FTIR technology is simple and quick,and is suitable for quality control and sample identification of A.konjac K.Koch.This provides a scientific basis for the quality control and comprehensive utilization of A.konjac K.Koch cultivated under forest.

Effects of Storage Temperature on Postharvest Physiology of Amorphophallus cormifer Microbulb

[Objectives]The paper was to explore the optimum storage temperature of Amorphophallus cormifer microbulbs.[Methods]With A.cormifer as the raw material,the effects of different storage temperatures(4,12 and 20℃)on postharvest physiology of A.cormifer during the storage period of 80 d were investigated.[Results]There was no significant difference in starch content among the treatments,and the content of reducing sugar at 4℃was significantly higher than those of other treatments during the storage period.There was no significant difference in total water content among treatments,and the specific gravity of free water at 4℃was significantly lower than those at 12 and 20℃,respectively.At 60 d post storage,the POD activity at 4℃was significantly higher than those at 12 and 20℃,respectively.At the 80th day of storage,the PPO activity at 4℃was significantly lower than those at 12 and 20℃,respectively.[Conclusions]The low temperature of 4℃is more conducive to the storage of A.cormifer microbulbs,and the results also provide the theoretical basis for long-term storage of A.cormifer bulbs.

魔芋(Amorphophallus spp.)四种组织器官RNA提取方法的比较

由于魔芋植株各部位富含多糖,较难获得高质量的RNA。为了筛选出魔芋各组织器官总RNA提取最适合的方法,本研究采用Trizol法、异硫氰酸胍法、改良CTAB法、RNAprep Pure Plant Kit和Plant RNA Kit五种方法分别对花魔芋叶片、茎杆、根和球茎四种组织部位的总RNA进行了提取,并用琼脂糖凝胶电泳和紫外分光光度计对RNA质量进行综合评价。结果表明:用Trizol法和异硫氰酸胍法提取魔芋各器官的RNA效果较差,杂质含量较高,降解严重;采用RNAprep Pure Plant Kit和Plant RNA Kit两种商业试剂盒仅提取出魔芋叶片的RNA,茎秆、根、球茎三种组织器官未能提取质量完整的RNA,所提取的RNA效果不稳定且浓度较低。改良CTAB法提取的魔芋四种组织器官RNA均能得到完整、清晰的RNA条带,且四个器官的OD260/OD280均在1.8~2.0之间,采用改良CTAB法提取魔芋各组织器官总RNA较为理想。本研究为不同器官来源魔芋植株样品的RNA提取方法提供了科学依据。

Studies on antibacterial screening of corm of Amorphophallus campanulatus (Roxb.)

Objective: To study the antibacterial screening of corm of Amorphophallus campanulatus (Roxb.) (A. campanulatus). Methods: Antibacterial activities of methanolic, petroleum ether and ethyl acetate extracts of corm of A. campanulatus were studied by agar diffusion technique to determine in vitro antibacterial activities. The antibacterial activity was measured with respect to the standard antibacterial drug. In addition, minimum inhibitory concentration was also determined by using serial dilution method to determine and evaluate antibacterial potency of test corm extracts of A. campanulatus. Results: The results showed significant antibacterial activities against four pathogenic bacteria. The minimum inhibitory concentration values against test bacteria were found to be remarkable range in bacteria like methicillin-resistant Staphylococcus aureus at concentration 0.25 mg/well, in Pseudomonas aeruginosa at 0.5 mg/well concentration, in Vibrio cholerae was 2 mg/well, Streptococcus pyogenes at concentration of 0.5 mg/well and Proteus mirabilis was at concentration of 2 mg/well. Conclusions: The methanolic and petroleum ether extracts are capable to maximum inhibition of the tested pathogenic bacteria.

油茶林下种植魔芋技术及效益分析

为提高成龄油茶(Camellia oleifera Abel.)林土地利用效率与综合产值,研究油茶+魔芋(Amorphophallus konjac)林农复合种植模式,探讨该模式下的种植技术及病虫害防治技术,并对其经济效益、社会效益和生态效益进行综合评价。结果表明,油茶林下种植魔芋的复合种植模式充分发挥了林地空间资源优势,达到以短养长,以农促林的效果,可有效解决油茶生产经营成本较高的问题,为油茶林复合经营提供参考。

农田草本植物控制魔芋软腐病的效果分析

植物多样性对魔芋(Amorphophallus konjac)软腐病有较好的控制效果。此试验通过对农田草本植物采用不同的管理方式,设5个杂草处理。处理A:草高于魔芋后清除1次杂草;处理B:7、8月各清除1次杂草;处理C:将高于魔芋的杂草在低于魔芋叶片处剪断;处理D:杂草自然生长;CK:没有杂草,即随时除净杂草。研究农田草本植物对魔芋软腐病的控制效果及对产量的影响。试验结果表明:处理B的控病、增产效果最好。处理A、B、C防控魔芋软腐病的效果与处理D相比,在1%水平上差异显著。处理A、B的产量与处理D相比,在1%水平上差异显著。处理A、B的产量与CK相比,在5%水平上差异显著。CK的产量与处理D相比,在5%水平上差异显著。

软腐菌识别侵染魔芋根部影响因子的研究

魔芋(Amorphophallus Konjac)软腐病频发已成为制约魔芋种植业发展的瓶颈。目前对其病原、发病规律及防治方法等进行了一些研究,加深了对魔芋软腐病的认识,取得了一定进展,但对魔芋软腐病的侵染和发病机制缺乏系统而深入的研究。通过测定软腐菌(Pectobacterium carotovora subsp.carotovora)在魔芋根表吸附量和根部侵入量,研究不同温度、p H、接种浓度、LPS和EPS对软腐菌在魔芋苗根部吸附和侵入过程的影响。结果表明,软腐菌在魔芋苗根部吸附侵入的最适温度条件是30℃、p H 6.0,随接种浓度增加吸附和侵入量增加;菌体LPS是魔芋软腐欧文氏菌对寄主根表的吸附所不可缺少的成分,而EPS预处理对吸附侵入量影响较小。本研究明确不同外界因子(温度、p H、接种浓度)和细菌识别子(EPS和LPS)在软腐菌吸附识别魔芋根际中的作用,从源头上了解软腐菌对魔芋根系的侵染机制,为研究病害循环和制订防治策略提供新的启示,从根本上有效控制魔芋病害的发生,并为魔芋的抗病育种提供新思路。

魔芋内生拮抗菌的定殖研究

采用抗魔芋(Amorphophallus rivieri Durieu)软腐病的内生芽孢杆菌BS-8发酵液灌根魔芋植株,定期测定该内生拮抗菌在魔芋叶片中的定殖情况。根据该内生菌16S rRNA特异性保守区域设计引物,定期4次采样,提取魔芋叶片DNA,通过SYBR Green I实时荧光定量PCR法检测该内生拮抗菌在魔芋叶片中的定殖情况。结果表明,经内生拮抗菌灌根培养的魔芋叶片中芽孢杆菌数量均明显大于对照,该内生芽孢杆菌能大量定殖在魔芋叶片中。

花魔芋离体再生体系的建立

以花魔芋（Amorphophallus konjac）为材料比较不同灭菌方式对不同外植体的灭菌效果及生长的影响,不同激素浓度及组合对魔芋愈伤组织、不定芽诱导的影响,探讨了固液2种培养方式对继代培养的影响。结果表明：球茎和根状茎均可作为较为理想的外植体;魔芋愈伤组织诱导最适激素组合为MS＋1.0mg/L 6-BA＋1.0 mg/L NAA,最适不定芽诱导培养基为MS＋2.0~2.5 mg/L 6-BA＋0.5 mg/L NAA或MS＋0.5mg/L TDZ＋0.1 mg/L NAA;液体培养更适合魔芋愈伤的继代增殖,其不定芽平均增殖率可达4.69。

不同遮阴度对魔芋软腐病的影响

通过调节魔芋(Amorphophallus konjac)/玉米(Zea mays L.)套作的种植密度来控制遮阴度,研究了不同遮阴度对魔芋软腐病发生的影响。结果表明,套作时玉米的种植密度在18 000～22 500株/hm2,魔芋的种植密度为37 500～45 000株/hm2时可显著降低魔芋软腐病的发生率。

魔芋飞粉/淀粉基共混膜的制备及性能研究

以魔芋(Amorphophallus rivieri)飞粉、淀粉为主要原料,以甘油为增塑剂,通过流延成膜法制备淀粉/飞粉共混薄膜,以耐水性和力学性能优化飞粉/淀粉的质量比,并从共混膜的相容性和热稳定性角度进行表征,研究魔芋飞粉共混膜的制备条件和膜性能。结果表明,共混膜的最佳飞粉/淀粉质量比为1∶3,此时吸水倍数为0.20 g/g,断裂强度为475.68 N,断裂伸长率为8.85 mm。红外和扫描电镜结果表明,具有网状结构的葡甘聚糖提高了膜的相容性和均匀度,膜的断裂强度和拉伸性增强;纯淀粉膜、交联淀粉膜和共混膜热失重为三阶段式,最终质量损伤率分别为82.91%、93.21%和80.27%;第一、二阶段峰温分别为87、303℃,75、309℃和83、282℃。与纯淀粉膜相比,飞粉淀粉共混膜相容性有所改善,并且更易热降解。

人工诱导珠芽黄魔芋开花结子研究

以珠芽黄魔芋(Amorphophallus konjac K.Koch)2个量级球茎为供试材料,采用喷施不同浓度梯度生长素和赤霉素等体积混合溶液,以及光照、自然阴干、花芽分化后和分化前埋入基质中的技术手段,探究人工诱导珠芽黄魔芋开花结子的方法。结果表明,2.0 kg及以上球茎的开花率均要高于1.0~1.5 kg的球茎,最高的开花率达93.33%;2.0 kg及以上球茎在光照处理条件下,生长调节剂浓度配比为1∶1 200,花芽分化后埋入基质中的结子率最高,达81.11%;2.0 kg及以上球茎在自然阴干处理条件下,生长调节剂浓度配比为1∶800,花芽分化后埋入基质中的种子数量最多,达4 442粒,繁殖倍数将近300倍。2.0 kg及以上的球茎,生长调节剂浓度配比为1∶400~1∶1 200,花芽分化后埋入基质中的方法可在生产实践中推广应用。

四种农药对魔芋软腐病病原菌的毒力测定

用抑菌圈法,在室内研究4种农药对魔芋(Amorphophallus konjac)软腐病病原菌的毒力大小。结果表明,4种农药对魔芋软腐病病原菌的毒杀力不同。以0.075%苦参碱的效果最佳,其EC_(50)为0.689 mg/L,其次为10.5%烟枯净,EC_(50)为0.950 mg/L,再次为36%农用硫酸链霉素,其EC_(50)为2.727 mg/L,12.5%氯溴异氰尿酸效果最差,其EC_(50)为4.821 mg/L。

不同因素对魔芋愈伤组织诱导及增殖分化的影响

以清江花魔芋1号为试材,分析了不同因素对魔芋(Amorphophallus)愈伤组织诱导与增殖分化的影响。结果表明,培养基中激素配比为MS+2.0 mg/L NAA+1.0 mg/L 6-BA或MS+2.0 mg/L 2,4-D+0.5 mg/L KT或MS+2.0 mg/L 2,4-D+1.0 mg/L KT时,均能获得较高的愈伤组织诱导率;4种外植体愈伤组织诱导率之间存在差异显著,诱导率大小依次为鳞片>球茎>叶片>根段;添加活性炭(AC)可明显增强愈伤组织诱导效果;在MS+2.0 mg/L TDZ+0.1 mg/L NAA培养基上愈伤组织分化形成不定芽的效果相对较好,分化率达96.15%,分化系数达9.52。

采用星点设计-响应面法制备魔芋片剂

以魔芋(Amorphophallus konjac)精粉为主要材料,采用星点设计-响应面法优化制备工艺。结果表明,0.24 g羟甲基淀粉钠、0.05 g硬脂酸镁、0.24 g聚维酮K 30、2.1 g可压性淀粉,所得片剂崩解性能优良,指标符合《中华人民共和国药典》2010版中对于片剂质量要求的相关规定。采用星点设计法优化魔芋片剂的制备工艺,其预测性良好,制得的魔芋片剂具有成型好、精确度高、稳定性好等特点。