ABSTRACT
Actin filaments play an important role in fungal life processes such as growth, development and cytokinesis. The expression vector pSULPH-Lifeact-mCherry of fluorescent mCherry-labeled actin was transferred into Verticillium dahliae Kleb. wild type V592 by the genetic transformation system mediated by Agrobacterium tumefaciens to obtain the stable fluorescent labeled actin strain V592/Lifeact-mCherry. Then we detected its biological phenotype and the dynamic changes of actin fluorescence during the process of spore germination, mycelial growth and development. There was no significant difference in the colony morphology, colonial growth rate, sporulation and germination rate between the fluorescent labeled actin strain and the wild type. The actin fluorescence signal was observed at the tip of the conidia and hyphae and the septum clearly. Actin participated in the formation of the contractile actomyosin ring (CAR) during cytokinesis by observing the dynamic behavior of the actin in the process of hyphal septum formation. The fluorescent labeled actin strain can be used to study the dynamics of actin in fungal development to provide theoretical and practical support for further study of the mechanism of actin in fungal development and pathogenesis.
Subject(s)
Actins , Agrobacterium tumefaciens , Plant Diseases , Spores, Fungal , VerticilliumABSTRACT
Okra (Abelmoschus esculentus (L.) Moench) has gained more popularity as an economically significant plant for its nutritional and medicinal value, especially in China. During 2014–2016, the root disease of okra was discovered in four okra commercial fields surveyed in China. A fungul was isolated from the infected tissues, and was identified by Verticillium dahliae based on morphological characteristics. Pathogenicity test demonstrated that the fungus was pathogenic on okra, and fulfilled Koch’s postulates. The analysis of three sequences revealed 99–100% identity with the reported V. dahliae strain in GenBank. Neighbor-joining analysis of the gene sequences revealed that the representative isolates were clustered with V. dahliae. To the best of our knowledge, this is the first report of Verticillium wilt of okra in China.
Subject(s)
Abelmoschus , China , Dahlia , Databases, Nucleic Acid , Fungi , Plants , Sequence Analysis , Verticillium , VirulenceABSTRACT
Fungal diseases are the main threat to crop yield and quality, often leading to huge economic losses. Chemical fungicides are almost useless to soil-borne and vascular fungal pathogens. The most effective way is crop resistance breeding by using resistance genes. Yet, for plants lacking resistance resources, new approaches are urgently needed for crop protection. Recently, host-induced gene silencing (HIGS) is developed based on the well-known RNA interference, and already effective against viruses and pests. However, it is challenging to validate HIGS in soil-borne fungal pathogens due to uncharacterized and complicated infection processes. Recently, we have made great progresses in revealing the infection structure of Verticillium dahliae, a soil-borne and vascular fungal pathogen that leads to verticillium wilt disease to many crops, including cotton plants. Moreover, we demonstrate that cotton exports endogenous microRNAs to inhibit virulence gene expression in V. dahliae. The most exciting achievement is the successful application of HIGS in cotton plants that confer resistance to V. dahliae. All these results reveal a promising potential for applying HIGS against a wide range of soil-borne fungi.
ABSTRACT
The Bacillus subtilis strain NCD-2 is an important biocontrol agent against cotton verticillium wilt and cotton sore shin in the field, which are caused by Verticillium dahliae Kleb and Rhizoctonia solani Kuhn, respectively. A mutant of strain NCD-2, designated M216, with decreased antagonism to V. dahliae and R. solani, was selected by mini-Tn10 mutagenesis and in vitro virulence screening. The inserted gene in the mutant was cloned and identified as the phoR gene, which encodes a sensor kinase in the PhoP/PhoR two-component system. Compared to the wild-type strain, the APase activities of the mutant was decreased significantly when cultured in low phosphate medium, but no obvious difference was observed when cultured in high phosphate medium. The mutant also grew more slowly on organic phosphate agar and lost its phosphatidylcholine-solubilizing ability. The suppression of cotton seedling damping-off in vivo and colonization of the rhizosphere of cotton also decreased in the mutant strain when compared with the wild type strain. All of these characteristics could be partially restored by complementation of the phoR gene in the M216 mutant.
ABSTRACT
Avaliou-se o potencial de rizobactérias na indução de resistência do algodoeiro à Xanthomonas axonopodis pv. malvacearum. Após o isolamento das rizobactérias, foram selecionados os isolados capazes de reduzir os sintomas da mancha angular bacteriana em casa de vegetação, os quais foram aplicados espacialmente separados do patógeno desafiador. Os melhores isolados foram testados quanto à capacidade de reduzir os sintomas da ramulose e da murcha de Verticillium e de inibir diretamente os patógenos in vitro. Do total de 123 isolados de rizobactérias foram selecionados cinco, L2-1 (Bacillus cereus), MT5-6 (Bacillus cereus), L2-2 (Achromobacter xylosoxidans), MT5-5 (Bacillus cereus) e MT5-11 (Brevibacterium sp.), os quais apresentaram controle da mancha angular acima de 40 por cento, em relação à testemunha. Nenhum isolado reduziu a severidade da ramulose e da murcha de Verticillium em relação à testemunha, nem apresentou efeito inibitório direto in vitro a X. axonopodis pv. malvacearum e Colletotrichum gossypii var. cephalosporioides. Para V. dahliae, apenas o isolado L2-1 apresentou efeito inibitório.
The potential of rhizobacteria was evaluated for resistance induction against Xanthomonas axonopodis pv. malvacearum. After isolation, the rhizobacteria were screened for the reduction of angular leaf spot severity under greenhouse conditions. They were spatially separated from the challenging pathogen. The best isolates were tested for the capacity to reduce ramulose and Verticillium wilt severity and directly inhibit pathogens in vitro. From a total of 123 rhizobacterial isolates, five were selected, L2-1 (Bacillus cereus), MT5-6 (Bacillus cereus), L2-2 (Achromobacter xylosoxidans), MT5-5 (Bacillus cereus) and MT5-11 (Brevibacterium sp.), which showed angular leaf spot control above 40 percent as compared to the control. The tested isolates neither reduced the severity of ramulose and verticillium wilt compared to the control nor showed in vitro direct inhibition to X. axonopodis pv. malvacearum and Colletotrichum gossypii var. cephalosporioides. For V. dahliae, only isolate L2-1 showed direct inhibition.
ABSTRACT
Twenty-nine antagonistic bacillus strains, isolated from some Chinese traditional medicine and fermented food , inhibit the growth of Fusarium oxysporum f. sp. Vasinfectum and Verticillium dahliae Kleb. And twelve of them are able to produce antagonistic proteins. Among the twelve strains, five (H110, H184, H216, B316 and B382) showed higher antibacterial activity. Furthermore, H110 and H184 were identified as Bacillus subtilis, and H216, B316 and B382 as Bacillus licheniformis based on physiological and biochemistry experiments. The antagonistic proteins of five strains were all thermostable, resistant to proteinase K and trypsin, while H184 and H216 partially sensitive to pepsin.