Banca de QUALIFICAÇÃO: LÍVIA FRANCYNE GOMES CHAVES

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : LÍVIA FRANCYNE GOMES CHAVES
DATE: 31/08/2021
TIME: 14:00
LOCAL: Google Meet
TITLE:

Begomovirus species infecting Cnidoscolus urens and study of Cnidoscolus mosaic leaf deformation virus transmission by seed

KEY WORDS:

Uncultivated plants; Euphorbiaceae; transmissibility

PAGES: 72
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Fitossanidade
SPECIALTY: Fitopatologia
SUMMARY:

Species of the genus Begomovirus (family Geminiviridae) cause damage to economically important crops around the world. However, wild/non-cultured hosts play a relevant epidemiological role, acting as a viral reservoir. These viruses are transmitted by a complex of cryptic species of the whitefly Bemisia tabaci, but, recently, transmissibility via seeds has been observed. Interestingly, Cnidoscolus urens plants are observed in the field with typical symptoms of begomovirus infection even in the apparent absence of the vector. In this context, the aim of the present study was to molecularly characterize new begomoviruses infecting C. urens, as well as to study the possible transmission of viruses by seeds. Leaf samples showing symptoms indicative of begomovirus infection were collected in the states of Pernambuco and Rio Grande do Norte, between 2019 and 2020. Total DNA was extracted from cansanção plants and later used as a template for rolling circle amplification (RCA), followed by cloning and sequencing by primer walking. In Paripueira, Alagoas, leaves, flowers and seeds of symptomatic plants were collected, as well as seedlings from infected seeds, and tested for Cnidoscolus mosaic leaf deformation virus (CnMLDV), using species-specific primers. A total of six clones of the DNA-A genomic component and two DNA-B clones were obtained. The DNA-A of the isolate from Paulista - PE shared the highest percentage of nucleotide identity (79.9%) with the Tomato common mosaic virus (ToCmMV; accession number KC706579), while the DNA-A from the isolate from Cabo de Santo Agostinho – PE obtained the highest percentage of nucleotide identity (88.9%) with CnMLDV (NC038982). The DNA-A component of the isolate from Goianinha - RN also shared the highest percentage of nucleotide identity (82.8%) with CnMLDV (NC038982). Based on the classification criteria for the genus Begomovirus, we report three new members infecting C. urens, and the names Begomovirus paulitiensis, Begomovirus caboniensis and Begomovirus goianiensis, respectively, are proposed for these viruses, adopting the binomial system. The results of detection of CnMLDV in plant parts revealed that 62% of the sepals, 79% of the androceum and 83% of the flowers, petals and gynoecium were infected. More than 90% of the seeds collected from C. urens infected with CnMLDV were positive. CnMLDV was also identified from integument, endosperm and embryo. However, no evidence of transmission of CnMLDV from seeds to seedlings was observed. Thus, suggesting that transmissibility via seeds is not a general property of the CnMLDV begomovirus.

BANKING MEMBERS:
Presidente - 2149632 - SARAH JACQUELINE CAVALCANTI DA SILVA
Interno - 051.040.974-12 - MARIOTE DOS SANTOS BRITO NETTO - UFRPE
Externo à Instituição - ROBERTO RAMOS SOBRINHO