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| Author(s): |
Juliana Ramiro
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 2011-02-02 |
| Examining board members: |
Nelson Sidnei Massola Júnior;
Edson Luiz Furtado;
Marcel Bellato Sposito
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| Advisor: | Nelson Sidnei Massola Júnior |
| Abstract | |
Colletorichum acutatum is the causal agent of postbloom fruit drop (PFD).This disease is a limiting factor for citrus production under specifics environmental conditions in several regions of the world. In addition to the PFD, this fungus causes anthracnose on other hosts. It is one of the pathogens that cause more damage in tropical, subtropical and temperate fruit around the world. This work aimed to study the specificity pathogenic and vegetative compatibility among isolates of C. acutatum from citrus and other hosts: guava, pepper, strawberry and peach. For studies of pathogenic specificity, cross inoculations were performed among isolates from citrus and other hosts in order to verify whether different strains are capable of causing symptoms of PFD in citrus flowers and fruit anthracnose. Furthermore, it was obtained from the same isolates, nitrate-nonutilizing mutants (nit mutants). They were phenotypically characterized and paired to verify, by means of vegetative compatibility studies, the ability of recombination between them, generating heterokaryons with altered pathogenicity. In order to verify the occurrence of possible changes in the pathogenicity of the heterokaryons formed, parental isolates and heterokaryons were inoculated in their respective original hosts. In cross-inoculation tests, there was a great variation in the isolates pathogenicity. Isolates from citrus and guava caused lesions on citrus blossoms; this demonstrates the absence of pathogenic specificity between isolates of the two hosts. However, isolates from pepper, peach and strawberry were unable to induce symptoms on citrus flowers showing the existence of specificity of these isolates. The strains from citrus and other hosts were able to cause anthracnose on guava, strawberry and peach, but only isolates of pepper caused anthracnose on pepper. Some isolates from citrus were able to recombine among themselves and with isolates from guava, peppers and strawberries. From the heterokaryons obtained, two of them had their pathogenicity characterized: Het 3 and Het 5. As a result, the heterokaryon derived from citrus and guava (Het 5) behaved similarly to one of their parental isolates. The heterokaryon derived from citrus and pepper (Het 3) was more aggressive than their parental isolates when inoculated in pepper. With these results we can conclude that there is specificity between pathogenic strains of C. acutatum from different hosts. However, isolates from different hosts can recombine with each other and generate heterokaryons with altered pathogenic characteristics. (AU) | |
| FAPESP's process: | 09/03224-1 - Pathogenic specificity and vegetative compatibility between Colletotrichum acutatum isolated from citrus and other hosts |
| Grantee: | Juliana Ramiro |
| Support Opportunities: | Scholarships in Brazil - Master |