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91.
Kristi Kabyashree Rahul Kumar Piyali Sen Siddhartha S. Satapathy Suvendra K. Ray 《Plant pathology》2020,69(7):1347-1356
Ralstonia solanacearum causes a lethal bacterial wilt disease in many plants by colonizing the vascular tissues of the hosts. Upon inoculation of tomato seedlings through either leaf or root, the wilting symptoms occur first at the apical region and then proceed downward along the shoot. The systemic order of the disease initiation and progression in the host, independent of the site of pathogen inoculation, is yet to be investigated. To understand the disease progression more clearly, we have carried out a systematic study of the pathogen localization by GUS staining of inoculated tomato seedlings, at 24-hour intervals from 0 days post-inoculation (dpi) to 5 dpi. In both inoculation methods, pathogen colonization was observed at 1 dpi at the apical meristem as well as the cotyledon leaves, where the disease initiates. As the disease progressed, colonization by the pathogen towards the lower region of the shoot was observed. Disease consistency and pathogenicity magnitude were observed to be higher using the leaf inoculation method than the root inoculation method. Several R. solanacearum transposon-induced mutants that were reduced in virulence by root inoculation but virulent by leaf inoculation were obtained. Using GUS staining, it was observed that these mutants were unable to localize in the shoot region when inoculated in the root. Our study indicates that the apical meristem and the cotyledon leaves are the first regions to be colonized in inoculated tomato seedlings, which might explain the disease initiation from this region. 相似文献
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在本工作中,通过平板筛选分离得到两个来自马铃薯的青枯假单胞菌菌株T2002和T2053(对花生不致病)的利福平抗性自发突变株T2016和T2017,通过三亲本接合,pGX1252分别以9.07×10-7、2.54×10-6频率被导入到T2016和T2017中,所得接合子T2123(T2016/pGX1252)和T2124(T2017/pGX1252)均分别能使花生汕油523发生青枯病,但它们侵染的植株出现病症的时间比T2005晚3~5d,说明pGX1252能扩大T2016和T2017的寄主范围使之包括花生。从侵染T2123、T2124的病株中重新分离病菌,四环素抗性检测和质粒检测表明所有细菌均含有pGX1252,说明在植物体内无抗生素选择压力情况下pGX1252能在T2016、T2017中稳定存在。本工作进一步证实pGX1252带有特异性控制青枯假单胞菌在花生上致病的与寄主专一性有关的基因。 相似文献
94.
采用番茄青枯病防治中3种已登记杀菌剂和7种未登记杀菌剂对番茄青枯病菌进行室内毒力测定,并通过EC50和病原菌的抗性水平进行抑菌作用对比。结果表明:在10种药剂中,以已登记的3%中生菌素WP抑菌效果最好,EC50值为1.308 mg/L,番茄青枯病菌对其表现敏感;在未登记的7种杀菌剂中,0.5%氨基寡糖素AS的抑菌效果最好,EC50值为2.180 mg/L,番茄青枯病菌对其表现敏感。 相似文献
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为筛选对桉树青枯病有防治效果的内生细菌,采用抑菌圈法,测定从青枯菌的非寄主植物中分离的内生细菌对青枯菌的拮抗作用,并分别在水培和土壤系统中测定其防治作用以及内生特性。结果表明:从蒜、葱、洋葱和葡萄内分离的14种可培养内生细菌中,只有菌株SH、SB、PT、C1和C2对青枯病菌具有拮抗作用;SH对C1具有拮抗作用,C2对SH有拮抗作用;在水培系统中,菌株SH对桉树青枯病的防治效果最好;在土壤系统中菌株PT、SH具有防治作用;菌株SH具有内生性,将桉苗浸于SH菌液中24 h,内生菌能侵入到桉苗茎部。 相似文献
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98.
The change in the nitrogen localized in the lamellae systems and stroma region of the rice chloroplast was pursued throughout the stages of growth and, further, the relationship between the composition of the chloroplast and leaf N content was examined. A common trend accompanying the stages of growth is recognized: that in the early stages of growth the amount of nitrogen existing as a form of stroma N is larger than that of lamellae N. Thereafter, stroma N tends to decrease in relation to lamellae N and finally, lamellae N becomes a dominant nitrogenous fraction in the chloroplast. The change in the composition of the chloroplast seems to be brought about by a change in the nitrogen metabolism of the chloroplast by which the distribution of absorbed nitrogen among the nitrogenous fractions of the chloroplast differs. 相似文献
99.
The effect of prior colonization of a sterile loam soil and a sterile clay loam soil by individual soil bacteria on the subsequent growth of a bacterial wilt pathogen Ralstonia solanacearum YU1Rif43 (tRNA type III: Seal et al. 1992: Appl. Environ. Microbiol., 58, 3759–3761) was investigated. Various strains, belonging to the same type, the same species, the same genus, Gram-negative, Grampositive, or fungi, were used. The degree of suppression of the growth of R. solanacearum YU1Rif43 was markedly different depending on the species that had previously colonized the soil, hereafter referred to as priorcolonists. All the strains belonging to R. solanacearum type III suppressed the growth of R. solanacearum YU1Rif43 markedly, while strains of R. solanacearum type I and type II showed a moderate suppressive effect on R. solanacearum YU1Rif43. The suppressive effect of the strains belonging to species other than R. solanacearum, including fungal strains, was relatively limited, or some strains did not show any suppressive effect. The production of bacteriocin did not appear to be related to the strong suppressive effect of the R. solanacearum type III strains. Possible mechanisms for the suppressive effect of priorcolonists on R. solanacearum YU1Rif43 are discussed in relation to nutrients and physical sites in soil available for growth. 相似文献
100.