Banca de DEFESA: Deziany da Silva Ferreira

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : Deziany da Silva Ferreira
DATE: 05/04/2024
TIME: 08:00
LOCAL: Videoconferência
TITLE:

"In plant validation of genes from wild Arachis species involved in Sclerotinia sclerotiorum resistance".

KEY WORDS:

Arachis duranensis, Arachis stenosperma, Sclerotinia sclerotiorum, white mold, defense genes, model plants.

PAGES: 140
BIG AREA: Ciências Biológicas
AREA: Biologia Geral
SUMMARY:

The fungus Sclerotinia sclerotiorum, responsible for white mold and stem rot diseases in various crops, is a necrotrophic organism that employs secreted proteins and metabolites to eliminate host cells. Current studies indicate that 425 species are documented hosts of this highly destructive fungus. Its survival primarily relies on sclerotia, which are aggregates of melanized hyphae persisting in the soil for extended periods. Sclerotia can germinate mycelogenically or carpogenically, with the latter being the dominant mode of infection. The fungus spreads through wind-borne ascospores, leading to direct plant infections under optimal temperature and humidity conditions. S. sclerotiorum is known to cause significant crop damage, resulting in substantial economic losses, especially in favorable environmental conditions. The absence of complete host resistance and the broad range of susceptible plants contribute to the detrimental impacts of this pathology, ranging from 35 to 50%, reaching more severe proportions of 80 to 100% in extreme situations. The presence of white mycelium in affected tissues is an identifiable sign, but no unique symptoms are common across all hosts. Resistance to S. sclerotiorum is crucial, and the wild relatives of peanuts emerge as valuable sources of disease-resistant genes. These wild species, such as A. duranensis and A. stenosperma, exhibit high levels of resistance to certain diseases, with previous studies prospecting and identifying genes from these species, utilizing transcriptomic approaches to understand responses to biotic and/or abiotic stresses. The present study examined the effects of overexpression of candidate genes from wild Arachis species, potentially involved in defense responses to biotic stresses. Using Arabidopsis thaliana and Nicotiana tabacum as model plants, the objective was to understand how these genes influence the interaction with S. sclerotiorum through phenotypic evaluations and subsequent molecular assessments. An inoculation methodology was initially established for detached leaves, with bioassays conducted using six genes from both A. duranensis and A. stenosperma. The study addressed the overexpression of specific genes, such as AdEXLB8 and AsTIR19, in transgenic plants to evaluate their impact on resistance to S. sclerotiorum. The overexpression of AdEXLB8 demonstrated increased tolerance, suggesting its potential as a candidate gene to enhance resistance through modifications in the cell wall and activation of phytohormone signaling pathways. The analysis of AsTIR19 highlighted the complexity of plant-pathogen interactions, providing insights into molecular mechanisms such as the induction of reactive oxygen species, and underscoring genetic engineering as a promising tool for improving resistance. Additionally, AsECHI1, both individually and in combination with AdEXLB8, led to a significant reduction in fungal lesions, indicating the effectiveness of pyramidal strategies in expanding the spectrum of resistance. On the other hand, the overexpression of the AsAOC3, AsTIL, and AsSTS4 transgenes did not exhibit a significant impact on the progression of the disease, emphasizing the intricate nature of gene-pathogen interactions and the necessity for more comprehensive approaches. The overexpression of these genes may offer an effective approach in developing resistant varieties to mitigate losses caused by S. sclerotiorum, emphasizing the importance of genetic investigation and the utilization of wild relatives in crop improvement.

COMMITTEE MEMBERS:
Interno - 6404906 - JUVENIL ENRIQUE CARES
Externa à Instituição - Lucilia Helena Marcellino - EMBRAPA
Externa à Instituição - MARIA EUGENIA LISEI DE SA - EMBRAPA
Presidente - 2644635 - ROBERT NEIL GERARD MILLER
Externo à Instituição - SILVINO INTRA MOREIRA - OUTROS