茄子抗青枯病基因的RAPD标记研究

 为探明茄子抗青枯病的遗传机制, 以高感青枯病品种北京六叶茄064, 高抗青枯病半栽培种马来西亚S3及其F₂ 代为材料, 用RAPD技术对供试材料的抗青枯病基因进行了研究。结果表明: 通过300个随机引物的PCR扩增分析, 发现15.6%的引物在双亲间表现出多态性, 找到了一个与茄子抗青枯病亲本S3中的抗病基因紧密连锁的分子标记S264₇₈₀ (该引物的碱基序列为CAGAGCGGA) , 该标记与S3的抗病基因的交换值为4.32% , 遗传距离为4.33 cM。     

Bacterial wilt of bellflower caused by Ralstonia solanacearum in Japan

A sudden wilt of bellflower (Campanula lactiflora) was observed in Japan in 1997. A bacterium that formed white fluidal and mucoid colonies resembling those of Ralstonia solanacearum was isolated from the infected plants. The bacterium was bacteriologically identified as biovar 3 of R. solanacearum. This is the first report of R. solanacearum affecting a plant species of the Campanulaceae family.     

云南红壤坡耕地秸秆配施复合菌剂的应用效应研究

基于大田试验和扩增子测序技术,分析在常规施肥（CK）基础上添加复合菌剂A(T1)、复合菌剂B(T2)、秸秆（T3）、秸秆+复合菌剂A(T4)和秸秆+复合菌剂B(T5)的处理对云南红壤坡耕地烟田综合应用效应的影响。结果表明,与CK处理相比,单施复合菌剂、秸秆还田及秸秆配施复合菌剂均能不同程度地提高红壤坡耕地土壤细菌群落丰富度、多样性和碱解氮、速效磷、速效钾含量、阳离子交换量及种植效益,改善上部烟叶化学成分的协调性和感官品质,整体以T5处理的综合应用效应较佳。综上,秸秆配施复合菌剂综合应用效应优于单施复合菌剂或单独秸秆还田,秸秆配施复合菌剂B更适合云南红壤坡耕地烤烟栽培。     

基于高通量测序的不同轮作方式下烟田土壤细菌群落组成分析

在自然界中,土壤微生物与植物之间存在着密切的联系,土壤微生物依赖植物提供的养分而生存,同时对植物的生长发育起着促进作用.本研究利用Illumina HiSeq高通量测序技术,提取西双版纳烟田烟草连作、田菁轮作和青蒿轮作3种种植模式下土壤样品的总DNA,通过PCR方法扩增构建16S rRNA基因文库.结合生物信息学方法分...     

Taxon-specific responses of soil bacteria to the addition of low level C inputs

The addition of small or trace amounts of carbon to soils can result in the release of 2-5 times more C as CO₂ than was added in the original solution. The identity of the microorganisms responsible for these so-called trigger effects remains largely unknown. This paper reports on the response of individual bacterial taxa to the addition of a range of ¹⁴C-glucose concentrations (150, 50 and 15 and 0 μg C g⁻¹ soil) similar to the low levels of labile C found in soil. Taxon-specific responses were identified using a modification of the stable isotope probing (SIP) protocol and the recovery of [¹⁴C] labelled ribosomal RNA using equilibrium density gradient centrifugation. This provided good resolution of the ‘heavy’ fractions ([¹⁴C] labelled RNA) from the ‘light’ fractions ([¹²C] unlabelled RNA). The extent of the separation was verified using autoradiography. The addition of [¹⁴C] glucose at all concentrations was characterised by changes in the relative intensity of particular bands. Canonical correspondence analysis (CCA) showed that the rRNA response in both the ‘heavy’ and ‘light’ fractions differed according to the concentration of glucose added but was most pronounced in soils amended with 150 μg C g⁻¹ soil. In the ‘heavy RNA’ fractions there was a clear separation between soils amended with 150 μg C g⁻¹ soil and those receiving 50 and 15 μg C g⁻¹ soil indicating that at low C inputs the microbial community response is quite distinct from that seen at higher concentrations. To investigate these differences further, bands that changed in relative intensity following amendment were excised from the DGGE gels, reamplified and sequenced. Sequence analysis identified 8 taxa that responded to glucose amendment (Bacillus, Pseudomonas, Burkholderia, Bradyrhizobium, Actinobacteria, Nitrosomonas, Acidobacteria and an uncultured β-proteobacteria). These results show that radioisotope probing (RNA-RIP) can be used successfully to study the fate of labile C substrates, such as glucose, in soil.     

稻田环境对鲤血清生化指标、肠道组织形态及细菌群落结构的影响

稻鱼共生(Rice-fish co-culture)作为“全球重要的农业遗产系统”,已成为我国发展可持续农业的重要模式。为研究稻田环境条件下,鲤血清生化特性、肠道显微结构及肠道微生物菌群多样性、物种丰度的影响。于2019年6月在连南瑶族自治县,分别选取稻田和池塘,放养规格大小一致的鲤幼鱼进行3个月的不投喂养殖。试验结束后统一进行采样与检测。结果表明：稻田环境显著提高了鲤的体长和体质量,显著降低了鲤血清谷丙转氨酶(ALT)活性和肠道微绒毛高度(P＜0.05),血清补体C3和C4的含量有上升趋势,但差异不显著(P＞0.05);在肠道微生物方面,稻田环境显著提高了鲤肠道内菌群多样性,并在门水平显著提高了疣微菌门(Verrucomicrobia)和变形菌门(Proteobacteria)的丰度(P＜0.05),显著降低了梭杆菌门(Fusobacteria)的丰度(P＜0.05);在纲水平,显著提高了α-变形菌纲(Alphaproteobacteria)和放线菌纲(Actinobacteria)的丰度;在属水平,显著降低鲸杆菌属(Cetobacterium)、邻单胞菌属(Plesiomonas)、拟杆菌属(Bacteroides)以及气单胞菌属(Aeromonas)的丰度(P＜0.05)。实验结果证实,稻田环境改变了肠道微生物多样性及与代谢能力有关的功能基因丰度,降低了部分条件致病菌的丰度,减少了疾病爆发的几率,同时有利于维持肝功能稳定。对于保持养殖鱼类健康生长有积极作用。     

水分管理对水稻籽粒硒积累及根际土壤细菌群落多样性的影响

采用盆栽试验方法,研究不同水分管理方式对水稻根际土壤硒组分、籽粒硒积累以及根际土壤细菌群落多样性的影响。结果表明：在水稻的各生育期,好氧和干湿交替较淹水灌溉一定程度上提高了土壤pH和氧化还原电位（Eh）,土壤可溶性和可交换态硒含量增加,从而提高了土壤硒的有效性。水稻成熟后,不同部位的含硒量由高到低依次为根（1.38~2.22 mg·kg^-1）、叶（0.55~0.85 mg·kg^-1）、茎（0.53~0.61 mg·kg^-1）和籽粒（0.15~0.53 mg·kg^-1）。水稻籽粒含硒量以干湿交替灌溉最高,淹水灌溉最低,二者含硒量差异达显著水平。干湿交替灌溉的水稻产量显著高于常规淹水灌溉,且较淹水灌溉提高了7.83%,较好氧灌溉提高13.51%。水稻根际土壤优势菌为变形菌门、绿弯菌门、拟杆菌门、酸杆菌门、Patescibacteria和芽单胞菌门,变形菌门是不同水分管理方式下水稻根际土壤中丰度最高的细菌,水分管理措施显著影响其丰富度,干湿交替和好氧灌溉中变形菌门的丰富度明显高于淹水灌溉。从纲水平看,Gammaproteobacteria的丰度与土壤有效硒含量呈正相关,故Gammaproteobacteria丰度的增加可能是土壤硒生物有效性增加的另一个重要原因。综上,干湿交替灌溉不但能提高水稻产量和稻米硒含量,且较正常淹水管理节约用水,在水稻生产中,是一种优先推荐的水分管理方法。     

浙江省蚕区桑树“凋萎”症状病因诊断

从浙江省临安、桐庐等地桑园中的"凋萎"桑树根、茎部获得151个细菌分离物样品。经离体水培接种试验表明,这些分离物均可引起桑树"凋萎"症状,其形态、大小、染色反应、培养性状与对照番茄青枯菌(Ralstonia so-lanacearum)相近;PCR鉴定其中125个分离物为雷尔氏菌(Ralstonia solanacearum)。结合田间发生症状,将桑树"凋萎"症状诊断为细菌性青枯病。从125个雷尔氏菌株中选择16个典型菌株进行研究,根据生理小种划分标准,这些菌株均为雷尔氏菌的生理小种1,其中75%为青枯菌的生化型Ⅴ、25%为青枯菌的生化型Ⅲ。