Immunocytochemical localization of callose in the vascular tissue of tomato and cotton plants infected with Fusarium oxysporum

1994 ◽  
Vol 72 (4) ◽  
pp. 505-509 ◽  
Author(s):  
W. C. Mueller ◽  
A. T. Morgham ◽  
E. M. Roberts

Callose (β-1,3-glucan) was localized with the electron microscope in the contact cells surrounding vessels of tomato and cotton infected with Fusarium oxysporum by means of gold labelling with a polyclonal antiserum to β-1,3-glucan. The callose was deposited in the apposition layers formed after infection in the cells surrounding initially infected vessels. Callose was not detected in the contact cells surrounding secondarily infected vessels. Callose could be detected in the contact cells of resistant and susceptible tomato cultivars 4 h after inoculation. Key words: β-1,3-glucans, contact cells, gold labelling, Gossypium, Lycopersicon esculentum.

Author(s):  
C. Booth

Abstract A description is provided for Fusarium oxysporum f.sp. vasinfectum. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Gossypium spp., and species of Cajanus, Coffea, Hevea, Hibiscus, Medicago, Ricinus, Solanum and Vigna. DISEASE: Vascular wilt or Fusariosis of cotton is a disease affecting its host at all stages of its growth. Early symptoms on seedlings consist of vein clearing of the leaves followed by necrosis of the interveinal tissue and death of the leaves. On older plants leaves become chlorotic and the vascular tissues show a brown discolouration. Growth is retarded and the plant eventually wilts. GEOGRAPHICAL DISTRIBUTION: Africa: Congo, Central African Republic, Egypt, Ethiopia, Madagascar, Senegal, Somalia, Sudan, South Africa, Tanganyika, Uganda; Asia: Burma, China, Formosa, India, Indo-China, Iran, Iraq, Pakistan, U.S.S.R. ; Europe: France, Greece, Italy, Romania, Yugoslavia; North America, Mexico, U.S.A. (cotton belt); Central America & West Indies: Guatemala, Nevis, Nicaragua, Puerto Rico, Salvador, St. Vincent; South America: Argentina, Brazil, Chile, Colombia, Peru, Venezuela. (C.M.I. Map 362). TRANSMISSION: Soil-borne, but may also be transmitted by water and seed. The pathogen has been recovered from delineated seed obtained from infected cotton plants in the Central African Republic, Congo, Tanganyika and Brazil (32: 186; 33: 143; 40: 754; 41: 389). The percentage infection ranged from 0.2 to 5.0.


2005 ◽  
Vol 30 (1) ◽  
pp. 26-32 ◽  
Author(s):  
Aldir de O. de Carvalho ◽  
Jorge Jacob Neto ◽  
Margarida Goréte F. do Carmo

Os objetivos do presente trabalho foram os de avaliar o efeito do pH sobre a germinação de conídios e o crescimento miceliano de F. oxysporum f. sp. lycopersici e o efeito da fonte de nitrogênio sobre o início do processo de infecção de raízes de mudas de tomateiro (Lycopersicon esculentum). Inicialmente quantificou-se a porcentagem de germinação dos conídios e o crescimento miceliano em meio Caldo Nutritivo com pH variando de 2,0 a 11,0. O pH do meio foi também medido ao final de 14 dias de crescimento do fungo. Avaliou-se, ainda, por meio de isolamentos e observações ao microscópio óptico, o efeito das fontes de nitrogênio sobre o processo de infecção e colonização das raízes. Utilizou-se a cultivar Kada Gigante e solução nutritiva contendo como fontes de nitrogênio N-NH4+, N-NO3- e N-NH4NO3, seguido da adição ou não de conídios do patógeno. As avaliações de pH da solução, das alterações morfológicas da raiz e da colonização pelo patógeno foram feitas até 240 h após a infestação. O N-NO3- proporcionou maiores valores de pH e favoreceu o desenvolvimento radicular, com aumento do tamanho e número de pêlos radiculares, e redução da taxa de adesão de conídios e da colonização por F. oxysporum f. sp. lycopersici comparado a N-NH4NO3 e, principalmente, N-NH4+. Estes resultados, porém, devem-se, mais provavelmente, ao desbalanço iônico nas plantas supridas com N-NH4+, do que ao efeito simples da variação de pH da rizosfera. O patógeno mostrou-se hábil em se desenvolver em faixa ampla de pH, 3 a 9, em meio de cultura.


2018 ◽  
Author(s):  
Qingqi Chen ◽  
Xiangyang Xu ◽  
Jingbin Jiang ◽  
Jingfu Li

Tomato yellow leaf curl virus (TYLCV) is one of the most devastating viruses of cultivated tomato in both tropical and subtropical regions. Five major genes (Ty-1, Ty-2, Ty-3, Ty-4 and Ty-5) from wild tomato species have been associated with resistance to TYLCV. Researchers have recently attempted to determine the functions of these resistance genes, but molecular mechanisms underlying the observed resistance remain unclear. Here, resistant (cv. CLN3212A-23, carrying Ty-5) and susceptible (cv. Moneymaker) plants were either left untreated (R and S, respectively) or artificially inoculated with TYLCV via Agrobacterium-mediated transformation (RT and ST, respectively). The transcriptomes of the plants in the four groups were then analyzed by RNA-Seq, and the results identified 8,639 differentially expressed genes (DEGs) between the R and RT groups, 2,818 DEGs between the RT and ST groups, 8,899 DEGs between the S and ST groups, and 707 DEGs between the R and S groups. The gene expression profiles in both the resistant and susceptible tomato cultivars appeared to undergo notable changes after viral inoculation, and functional classification revealed that most DEGs were associated with 18 GO terms. Moreover, the functional classification of the response of Ty-5-carrying tomato plants to TYLCV infection identified the importance of the GO term “response to stimulus” in the BP category, which is related to disease resistance. In addition, 28 genes were significantly enriched in the “Plant hormone signal transduction”, “Carbon metabolism”, “ Carbon fixation in photosynthetic organisms ” and “ Glutathione metabolism ” pathways. The differential expression levels of 12 select genes were confirmed by quantitative real-time PCR. The present study indicates that the Ty-5 gene activates the expression of multiple genes involved in the resistance process and will aid a more in-depth understanding of the effects of the Ty-5 gene on resistance based on its molecular mechanism with the aim of improving TYLCV disease management in tomato.


2014 ◽  
Vol 11 (2) ◽  
pp. 813-818
Author(s):  
Baghdad Science Journal

Research was conducted to study the effect of proline and aspirin with 10 and 20 ppm on seed germination and seedling growth of Lycopersicon esculentum and the effect of surface growth of Fusarium oxysporum. The results showed that the proline and aspirin effected significantly to decreased percentage of seed germination, acceleration of germination, promoter indicator, elongation speed of radical and plumule and also the infection percentage of seed decay and surface growth of Fusarium oxysporum was reduced significantly.


2016 ◽  
Vol 83 (4) ◽  
Author(s):  
V. Chellappan Biju ◽  
Like Fokkens ◽  
Petra M. Houterman ◽  
Martijn Rep ◽  
Ben J. C. Cornelissen

ABSTRACT Race 1 isolates of Fusarium oxysporum f. sp. lycopersici (FOL) are characterized by the presence of AVR1 in their genomes. The product of this gene, Avr1, triggers resistance in tomato cultivars carrying resistance gene I. In FOL race 2 and race 3 isolates, AVR1 is absent, and hence they are virulent on tomato cultivars carrying I. In this study, we analyzed an approximately 100-kb genomic fragment containing the AVR1 locus of FOL race 1 isolate 004 (FOL004) and compared it to the sequenced genome of FOL race 2 isolate 4287 (FOL4287). A genomic fragment of 31 kb containing AVR1 was found to be missing in FOL4287. Further analysis suggests that race 2 evolved from race 1 by deletion of this 31-kb fragment due to a recombination event between two transposable elements bordering the fragment. A worldwide collection of 71 FOL isolates representing races 1, 2, and 3, all known vegetative compatibility groups (VCGs), and five continents was subjected to PCR analysis of the AVR1 locus, including the two bordering transposable elements. Based on phylogenetic analysis using the EF1-α gene, five evolutionary lineages for FOL that correlate well with VCGs were identified. More importantly, we show that FOL races evolved in a stepwise manner within each VCG by the loss of function of avirulence genes in a number of alternative ways. IMPORTANCE Plant-pathogenic microorganisms frequently mutate to overcome disease resistance genes that have been introduced in crops. For the fungus Fusarium oxysporum f. sp. lycopersici, the causal agent of Fusarium wilt in tomato, we have identified the nature of the mutations that have led to the overcoming of the I and I-2 resistance genes in all five known clonal lineages, which include a newly discovered lineage. Five different deletion events, at least several of which are caused by recombination between transposable elements, have led to loss of AVR1 and overcoming of I. Two new events affecting AVR2 that led to overcoming of I-2 have been identified. We propose a reconstruction of the evolution of races in FOL, in which the same mutations in AVR2 and AVR3 have occurred in different lineages and the FOL pathogenicity chromosome has been transferred to new lineages several times.


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