Effect of K1, K2 Anti-Bacterial Agents on Tobacco Ralstonia Solanacearum

The tobacco Ralstonia Solanacearum were both cultured on nutrient agar plates and inoculated in seedling stage of tobacco, then treated with K1 and K2, two anti-bacterial agents, at a serial con-centrations to study their inhibitory efficiency. The result indicated that K1 can inhibit R. Solanacearum growth entirely, at the concentration range from 1/50 to 1/5000. K2 can reach the same result at the concentration range from 1/50 to 1/50000. Compared with the control plates, K1, at the concentration 1/50000, had no significant differences, and the average number of colony per plate was 112-115. The immature tobacco shown wilt as soon as inoculated with R. Solanacearum, and recovered gradually after using K1, K2. The densities of microbial suspension, handled by K1, K2 within 10 hs, were both significantly lower than the controlled ones. The optical microscopy also shown that handled microbial body differed from the controlled, whose body was regular short, rod shape as opposed to the handled ones with irregular rod shape and damaged body. All the results indicated that K1 and K2 both had inhibitory effects on tobacco R. Solanacearum, and K2 was more efficient than K1.

桑青枯雷尔氏菌MR111的16S rDNA基因序列测定和系统进化分析

对从发病的桑树中分离出的菌株MR111的16S rDNA进行PCR扩增和序列分析。结果表明:对菌株MR111进行16SrDNA的PCR扩增,获得了1 435 bp 16S rDNA序列。NCBI在线BLAST分析表明,该序列与茄科雷尔氏菌PC-3、RSGC-1等序列的同源性达95%。对28个茄科雷尔氏菌菌株的16S rDNA序列进行系统进化分析,MR111与来自空心菜(GY0501)、番茄(ZCz-3)等的菌株聚合在一个簇群,证实该菌株为青枯雷尔氏菌。命名为桑青枯雷尔氏菌MR111a。

番茄新品种特宝1号苗期对青枯病的抗性测定

对从荷兰引进的番茄新品种特宝1号进行番茄青枯病(R a lston ia solanacearum)抗性测定试验,结果表明,该品种表现出较好的抗性。苗期人工接种后,30d才出现症状,比抗病品种抗青1号的发病时间推迟15d,发病率低且病害发展缓慢,校正发病率差异达到极显著水平。该品种还具有早熟、生长势强、不易早衰、丰产性好和特别耐贮运等特点。

罗尔斯通菌去除土壤重金属铅的效能及机制

从矿区土壤分离得到的罗尔斯通菌(Ralstonia Bcul-1)对重金属离子具有广谱抗性,可在重金属铅含量为87.35 mg·kg^(-1)的酸性土壤生长(pH 5.62)。低浓度Pb^(2+)可诱导部分重金属抗性基因表达,但高浓度Pb^(2+)(>15 mg·L^(-1))则抑制这些基因的表达。在Pb^(2+)胁迫下,一些蛋白质的表达同样受到诱导或者抑制。重金属抗性基因和抗性蛋白的表达使Ralstonia Bcul-1能够适应重金属铅污染的生存环境。在含Pb^(2+)的液体培养基中(pH<6.50),Ralstonia Bcul-1菌体对Pb^(2+)的去除效率高达8.22%~29.09%。将Ralstonia Bcul-1接菌到受重金属铅污染的酸性菜园土壤中(pH 5.32,重金属铅总含量为94.37 mg·kg^(-1)),在没有添加任何营养物质的条件下,Ralstonia Bcul-1能持续生长达12 d,并且对土壤悬浮物(包括泥浆)重金属铅的去除效率达到12.71%~24.71%(土壤悬浮物的重金属铅含量为32.67 mg·kg^(-1))。研究结果表明,Ralstonia Bcul-1能在重金属铅污染的酸性菜园土壤中存活,并对土壤悬浮物的重金属铅有较强的去除效率,具有修复土壤重金属铅污染的潜力。

受病原物诱导的植物启动子PPPs在转基因辣椒中的活性

按GenBank中受病原物诱导的植物启动子(PPPs)的碱基序列设计3对引物,从烟草基因组中扩增到3个启动子PPP1,PPP2和PPP3.用PPPs替换pBI121中与uidA基因(编码β-葡萄糖醛酸酶GUS)相连的35S启动子,再将重组质粒导入农杆菌GV3101,构建了PPPs和uidA相连的转化单元.通过农杆菌介导法将受PPPs控制的uidA基因导入辣椒.对转基因辣椒叶片接种青枯菌无致病性菌株(AVRS1),24 h后检测GUS活性.结果表明,接种AVRS1后,PPPs启动了uidA的表达,GUS活性显著增强.

青枯菌对花生发芽率及芽长的影响

花生青枯病严重影响花生的产量和品质,了解青枯菌对花生发芽和生长的影响是研究青枯病作用机制以及信号转导途径的前提。为检测强致病力青枯菌对"日花1号"种子发芽的影响,采用发芽试验对种子发芽(露白)率以及芽长进行检测,并用荧光定量PCR方法检测了植物抗病相关基因非病程相关基因表达子1(NPR1)在青枯菌胁迫条件下的表达变化规律。结果表明,经过青枯菌浸泡的种子,发芽受到明显抑制,芽长较对照组亦明显变短。在胁迫条件下NPR1的表达量在第12h达到最高,随后缓慢降低,第48h的表达量仍未恢复到初始水平,是初始水平的1.7倍。

Intra-strain Elicitation and Suppression of Plant Immunity by Ralstonia solanacearum Type-III Effectors in Nicotiana benthamiana

Effector proteins delivered inside plant cells are powerful weapons for bacterial pathogens,but this exposes the pathogen to potential recognition by the plant immune system.Therefore,the effector repertoire of a given pathogen must be balanced for a successful infection.Ralstonia solanacearum is an aggressive pathogen with a large repertoire of secreted effectors.One of these effectors,RipE1,is conserved in most R.solanacearum strains sequenced to date.In this work,we found that RipE1 triggers immunity in N.benthamiana,which requires the immune regulator SGT1,but not EDS1 or NRCs.Interestingly,RipE1-triggered immunity induces the accumulation of salicylic acid(SA)and the overexpression of several genes encoding phenylalanine-ammonia lyases(PALs),suggesting that the unconventional PALmediated pathway is responsible for the observed SA biosynthesis.Surprisingly,RipE1 recognition also induces the expression of jasmonic acid(JA)-responsive genes and JA biosynthesis,suggesting that both SA and JA may act cooperatively in response to RipE1.We further found that RipE1 expression leads to the accumulation of glutathione in plant cells,which precedes the activation of immune responses.R.solanacearum secretes another effector,RipAY,which is known to inhibit immune responses by degrading cellular glutathione.Accordingly,RipAY inhibits RipE1-triggered immune responses.This work shows a strategy employed by R.solanacearum to counteract the perception of its effector proteins by plant immune system.

Ⅲ型效应子GALA对青枯菌在两种寄主植物上致病性的影响（英文）

【目的】研究III型效应子GALAs对青枯菌OE1-1在不同寄主植物致病性上的影响。【方法】构建青枯菌OE1-1的多种GALA缺失突变体,通过根切和叶片注射等方法研究GALAs对青枯菌OE1-1致病力和细胞内增殖能力的影响。【结果】GALA多基因缺失突变体对寄主烟草的致病力减弱,在烟草体内细菌繁殖能力较野生型明显降低,但在寄主番茄上不影响其致病性。【结论】GALA效应子对青枯菌OE1-1在烟草植株致病性上展现协同作用。

应用竞争力指数分析Ⅲ型效应子SKWP对青枯菌在寄主植物体内增殖能力的影响（英文）

【目的】研究Ⅲ型效应子SKWP对青枯菌OE1-1在寄主植物体内增殖能力的影响。【方法】构建青枯菌RK7197(野生型突变体,带Gm抗性)和SKWP单基因缺失突变体(带PB抗性),通过竞争力指数分析SKWP各效应子对青枯菌OE1-1在叶片组织内增殖能力的影响。【结果】竞争力指数适合在寄主植物茄子上分析各效应子功能,6个SKWP效应子对OE1-1细菌增殖能力影响不同,SKWP4影响最明显。【结论】竞争力指数可提供一个新视野来分析SKWP各效应子对青枯菌OE1-1在寄主茄子上增殖能力的影响。