A novel technique using 1-MCP microbubbles for delaying postharvest ripening of banana fruit

This study aimed to investigate the application of microbubble technology for delaying banana ripening. A preparation of 1-MCP designed for use as a form of aqueous micro bubble (MBs) solutions was formulated. Banana fruit were immersed in 500 nL L⁻¹ of aqueous 1-MCP microbubbles (1-MCP-MBs) or fumigated with 500 nL L⁻¹ 1-MCP, then stored at 25 °C for 8 days. 1-MCP-MBs were more effective in delaying postharvest ripening than conventional 1-MCP fumigation. 1-MCP-MBs reduced the respiration rate and ethylene production compared to the control and 1-MCP fumigated fruit. Moreover, 1-MCP-MBs delayed yellowing and maintained firmness of banana fruit during storage. These results indicate that 1-MCP-MBs can be used as an alternative method for delaying the postharvest ripening of banana fruit, and its application for other commodities needs to be further elucidated.     

不同品种与成熟度原料对香蕉片真空干制品质的影响

[目的]研究香蕉不同品种和成熟度的真空干制特性。[方法]以当地产的成熟香牙蕉、粉蕉、大蕉、鸡蕉为试材,对其分别进行浸药预处理和冷冻预处理后,在65℃和-0.1 MPa条件下进行真空干燥,测定制好的香蕉干片的总糖和复水性能,并评价其感官品质,研究香蕉不同品种与成熟度原料对香蕉片真空干制品质的影响。[结果]以经浸药预处理的香牙蕉干片和经冷冻预处理的粉蕉干片的真空干制品质最好,复水性最好的是香牙蕉干片,得率最高的是粉蕉干片。在适宜的成熟度范围内,香牙蕉和粉蕉的成熟度越高,其干制品的感观品质和理化品质就越好,但得率随着成熟度的升高而略有降低。[结论]香牙蕉和粉蕉适于香蕉干制,且香牙蕉和粉蕉分别适于采用浸药、冷冻方法进行预处理。     

香蕉条斑病毒LAMP快速检测方法的建立

 环介导等温扩增（loop-mediated isothermal amplification,LAMP）是一种特异、灵敏、快速的新型基因检测技术。本研究以香蕉条斑病毒（Banana streak virus,BSV）ORF3保守区域为基础针对6个特定区域设计并筛选了4条LAMP扩增引物,通过对LAMP反应中MgSO₄、dNTPs、Betaine等主要试剂浓度进行优化,建立了香蕉BSV的LAMP检测方法,63℃反应90 min后通过在反应产物中添加SYBR Green Ⅰ染料后颜色的变化,肉眼即可判断检测结果。LAMP具有极高的检测特异性和灵敏性,其检测下限约为3.2 ng·μL^-1,是PCR检测灵敏度的25倍,能快速、准确地对疑似样品进行检测,本研究对华南地区部分疑似样品的检测结果显示LAMP阳性检出率比PCR检出率高。本文建立的BSV LAMP检测方法是对BSV检测方法的拓展和延伸,为香蕉病毒的快速检测提供技术保障。     

Induction of systemic resistance in banana (<Emphasis Type="Italic">Musa</Emphasis> spp.) against <Emphasis Type="Italic">Banana bunchy top virus</Emphasis> (BBTV) by combining chitin with root-colonizing <Emphasis Type="Italic">Pseudomonas fluorescens</Emphasis> strain CHA0

Pseudomonas fluorescens strains CHA0 and Pf1 were investigated for their biocontrol efficacy against Banana bunchy top virus (BBTV) in banana (Musa spp.) alone and in combination with chitin under glasshouse and field conditions. Bioformulation of P. fluorescens strain CHA0 with chitin was effective in reducing the banana bunchy top disease (BBTD) incidence in banana under glasshouse and field conditions. In addition to disease control, the bioformulation increased the economic yield significantly compared to the untreated control. Increased accumulation of oxidative enzymes, peroxidase (PO), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), pathogenesis-related (PR) proteins, chitinase, β-1,3-glucanase and phenolics were observed in CHA0 bioformulation amended with chitin-treated plants challenged with BBTV under glasshouse conditions. Indirect ELISA indicated the reduction in viral antigen concentration in P. fluorescens strain CHA0 with chitin-treated banana plants corresponding to reduced disease ratings. The present study revealed that induction of defence enzymes by P. fluorescens with chitin amendment reduced the BBTD incidence and increased bunch yield in banana.     

A rapid technique for screening banana cultivars for resistance to Xanthomonas wilt

The banana Xanthomonas wilt disease (BXW) has threatened the livelihood of millions of farmers in East Africa. Use of resistant varieties is the most cost-effective method of managing this bacterial disease. A reliable and rapid screening method is needed to select resistant banana varieties. An in vitro screening method was developed for early evaluation of Xanthomonas wilt resistance using small tissue culture-grown plantlets. Eight cultivars of banana were screened with sixteen isolates of Xanthomonas campestris pv. musacearum using this method. There were significant differences (P < 0.0001) in susceptibility among the various banana cultivars tested, whereas no significant difference (P = 0.92) in pathogenicity was observed between the pathogen isolates. The cv. Pisang Awak (Kayinja) was found to be highly susceptible and Musa balbisiana resistant. Nakitembe was found to be moderately resistant while cvs Mpologoma, Mbwazirume, Sukali Ndiizi, FHIA-17 and FHIA-25 were susceptible. The susceptibility of these cultivars was further tested in vivo by artificial inoculation of potted plants with similar results. This study shows that an in vitro screening test can serve as a convenient, cheap and rapid screening technique to discriminate BXW-resistant from BXW-susceptible banana cultivars.     

应用TaqMan real-time PCR研究BSV在带毒香蕉组培苗中传递

由香蕉线条病毒(Banana streak virus,BSV)引起的香蕉线条病,严重影响了香蕉产量及种质资源交流。本研究根据BSV ORF Ⅲ基因保守序列设计引物和探针,建立了BSV的实时荧光定量PCR检测方法。该法检测BSV时,与黄瓜花叶病毒(Cucumber mosaic virus,CMV)和香蕉束顶病毒(Banana bunchy top virus,BBTV)无交叉反应;不论是检测质粒DNA还是香蕉病株总DNA,其灵敏度都比普通PCR高,检测质粒DNA的灵敏度比普通PCR高100倍,检测香蕉病株总DNA的灵敏度比普通PCR高10倍,且具有良好的重复性。利用建立的实时荧光定量PCR方法检测我国主栽的不同香蕉品种‘大蕉’、‘粉蕉’和‘粤优抗一号’香蕉组培苗中BSV的浓度,发现不同品种BSV传递规律不同。‘大蕉’第3代、第9代组培分化芽中BSV含量较原代显著减少;‘粉蕉’中BSV含量随继代数增加表现为先增加后减少;‘粤优抗一号’中BSV含量随继代数增加呈增加趋势。BSV在‘粉蕉’、‘大蕉’和‘粤优抗一号’第10代到第12代组培苗中以顶部第1片或(及)第2片叶中含量最高。直接结合PCR分析初步表明不同品种在原代和组培至第12代,其植株中的BSV均为游离状态。本文通过对带毒香蕉组培苗中BSV的含量监测,明确了BSV在不同品种带毒香蕉组培苗中的传递和分布规律,为研究BSV与寄主互作及BSV检测提供了理论依据。     

香蕉果实抗性淀粉含量变化及其与其他类型淀粉相关性分析

【目的】研究香蕉果实抗性淀粉形成机理,为选育高抗性淀粉香蕉品种和调控抗性淀粉合成提供理论基础。【方法】以 ‘巴西’蕉（Musa acuminata L. AAA group cv. Brazilian）果肉为试材,对香蕉果实采前和采后抗性淀粉含量变化及其与其他类型淀粉相关关系进行分析。【结果】香蕉果实发育过程中,总淀粉、直链淀粉、支链淀粉及抗性淀粉含量整体呈上升趋势,后熟过程中各种淀粉含量逐渐下降;乙烯处理加速了总淀粉、直链淀粉和支链淀粉的降解,但抗性淀粉降解速度较自然后熟慢;1-MCP处理香蕉果实各种淀粉含量呈先增后降的单峰曲线变化。相关性分析表明：香蕉采前果实抗性淀粉合成与直链淀粉含量变化呈显著正相关,与总淀粉和支链淀粉含量变化不相关;1-MCP处理后,抗性淀粉含量变化与直链淀粉含量达到显著正相关水平,与总淀粉含量变化不相关。【结论】香蕉果实抗性淀粉形成与直链淀粉含量密切相关,在香蕉果实发育过程中可通过调控直链淀粉含量促进抗性淀粉合成。     

Banana Prevents Plasma Oxidative Stress in Healthy Individuals

There is increasing evidence that lipid peroxidation and oxidative modification of low density lipoprotein (LDL) is important in atherogenesis. The present study was designed to study the effects of a single banana meal on plasma lipids and lipoprotein profile, plasma oxidative stress and susceptibility of LDL to oxidation in 20 healthy volunteers. Lipid and lipid peroxide (LPO) levels were measured before the meal (baseline, fasting) and 2 h after it (post-dose). The susceptibility to copper-induced oxidation of baseline and post-dose LDL was measured as conjugated diene (CD) formation. Results showed that the LPO contents in plasma, very low density lipoprotein (VLDL), LDL and high density lipoprotein (HDL) decreased significantly in the 2 h post-dose phase. Prolongation of lag phase and decrease of CD formation during LDL oxidation indicated that post-dose LDL was less susceptible to oxidative modification than the homologous fasting LDL. In conclusion, the consumption of banana reduces the plasma oxidative stress and enhances the resistance to oxidative modification of LDL.     

不同添加剂对香蕉假茎青贮的影响

以经过干制的假茎(干物质含量约为25%)为原料,分别添加甲酸、EM、青宝Ⅱ号、EM+青宝Ⅱ号进行青贮以探讨香蕉假茎通过青贮转化作为饲料的效果。结果表明：加入添加剂处理可以提高青贮品质,与对照相比各处理组在pH值、氨态氮、ADF测定中均显著降低(p<0.05);EM+青宝Ⅱ号组效果最好pH值为3.9,ADF含量下降了7.86%;EM效果次之,但这两者之间的差异不显著。     

香蕉枯萎病发病机制及其防治技术研究

从香蕉枯萎病的病原菌及其发病机制和香蕉抗病机制等多方面阐述了国内外的研究进展,研究表明枯萎病菌的4号小种对中国香蕉生产影响最大,果胶酶和毒素是引起香蕉致病的主要毒力因子,此外,还有一些小分子的成分和作用有待进一步明确。阐述了香蕉枯萎病的防治现状。