Banca de QUALIFICAÇÃO: GEORGIA DE SOUZA PEIXINHO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : GEORGIA DE SOUZA PEIXINHO
DATE: 24/02/2022
TIME: 09:00
LOCAL: Sala Virtual Googlemeet
TITLE:

CHARACTERIZATION OF Colletotrichum spp. ASSOCIATED WITH ANTHRACNOSIS IN TROPICAL FLOWERS IN NORTHEAST BRAZIL AND USE OF ESSENTIAL OILS IN DISEASE CONTROL

KEY WORDS:

cut flower, inflorescence, post-harvest, disease, fungus

PAGES: 108
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Fitossanidade
SPECIALTY: Fitopatologia
SUMMARY:

Anthracnose is the main disease caused by the species of this genus and occurs on a wide range of hosts. In species of the tropical flowers the disease causes serious problems in productivity, mainly in tropical and subtropical regions. Although more species of the genus have been reported causing anthracnose in tropical flowers in different parts of the world, little is known about the etiology of the disease in Brazil. Therefore, the objective of this study wereto identify species of the genus Colletotrichum through molecular and morphocultural characterization associated with different species of tropical flowers, to evaluate the cross-pathogenicity of the different species of Colletotrichum identified and to test different essential oils to control the disease. For molecular characterization, the genomic DNA of the isolates were used by the CTAB 2% protocol with modifications. The partial sequence of the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene was amplified using the GDF/GDR primers, for a preliminary identification of the isolates and evaluation of the haplotypic diversity of the species. Subsequently, representatives of each species, based on haplotypes, were amplified with another gene, β-tubulin (TUB2), and the ITS-rDNA region. The cultural characterization consisted of obtaining the mycelial growth of the colonies, through daily measurement in two diametrically opposite directions and observation of the color of the colonies evaluated after seven days. Morphological characterization was based on the shape and size of 50 conidia and appressoria. Length and width measurements were obtained through images captured by a digital camera attached to an optical microscope with a 400x magnification, using Cellsenses Standard software. The mycelial growth of Colletotrichum spp. in Petri dishes containing PDA medium supplemented with the following chemicals: mancozeb (240g); methyl thiophanate (45 g.L-1) and essential oils: lemongrass, citronella and mint essential oil (0.75; 1.5; 2.25 and 3%) and ADE for all controls. The selected in vitro treatments were used in the in vivo experiment, applied 72 and 48 hours before inoculation of the pathogen (resistance inducer) and 72 and 48 hours after inoculation (dressing), for the first experiment. In the second experiment, citronella and mint oils (0.25; 0.5; 0.75 and 1%) and methyl thiophanate (45 gL-1) were used, separately, 72 and 48 hours before inoculation (inducing resistance) and 72 and 48 hours after inoculation (dressing). The inflorescences were submitted to inoculation with the pathogen, through the spraying method (106 con./mL). After 4 days, the disease index and severity and incidence were determined. The data were submitted to analysis of variance (ANOVA), and when there were significant differences, the averages of the treatments were compared by the Scott-Knott Test at a 5% probability level, using the SISVAR program. The compounds present in the essential oils were determined. It was possible to identify five species within the C. gloesporioides and C. orchidearum complexes. The essential oils of citronella, lemongrass and mint reduced the severity of the disease.

BANKING MEMBERS:
Presidente - 1119045 - EDNA PEIXOTO DA ROCHA AMORIM
Externa ao Programa - 032.999.174-47 - JULIANA PAIVA CARNAUBA - IFAL
Interna - 2149632 - SARAH JACQUELINE CAVALCANTI DA SILVA