Type IV Secretion System Is Not Involved in Infection Process in Citrus.
The type IV secretion system (T4SS) is used by Gram-negative bacteria to translocate protein and DNA substrates across the cell envelope and into target cells. Xanthomonas citri subsp. citri contains two copies of the T4SS, one in the chromosome and the other is plasmid-encoded. To understand the conditions that induce expression of the T4SS in Xcc, we analyzed, in vitro and in planta, the expression of 18 ORFs from the T4SS and 7 hypothetical flanking genes by RT-qPCR. As a positive control, we also evaluated the expression of 29 ORFs from the type III secretion system (T3SS), since these genes are known to be expressed during plant infection condition, but not necessarily in standard culture medium. From the 29 T3SS genes analyzed by qPCR, only hrpA was downregulated at 72 h after inoculation. All genes associated with the T4SS were downregulated on Citrus leaves 72 h after inoculation. Our results showed that unlike the T3SS, the T4SS is not induced during the infection process.
Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, Departamento de Tecnologia, Universidade Estadual Paulista (UNESP), 14.884-900 Jaboticabal, SP, Brazil.
Tiago Rinaldi
TR
Jacob
Departamento de Engenharia Florestal, Faculdade de Ciências Agrárias, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 39.100-000 Diamantina, MG, Brazil.
Marcelo Luiz
ML
de Laia
Departamento de Ciências Biológicas (DECBI), Instituto de Ciências Exatas e Biológicas (ICEB) and Núcleo de Pesquisas em Ciências Biológicas (NUPEB), Universidade Federal de Ouro Preto, 35.400-000 Ouro Preto, MG, Brazil.
Leandro Marcio
LM
Moreira
Departamento de Engenharia Florestal, Faculdade de Ciências Agrárias, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 39.100-000 Diamantina, MG, Brazil.
Janaína Fernandes
JF
Gonçalves
Embrapa Informática Agropecuária, CNPTIA-EMBRAPA, Campinas, SP, Brazil.
Flavia Maria de Souza
FM
Carvalho
Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, Departamento de Tecnologia, Universidade Estadual Paulista (UNESP), 14.884-900 Jaboticabal, SP, Brazil.
Maria Inês Tiraboschi
MI
Ferro
Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, Departamento de Tecnologia, Universidade Estadual Paulista (UNESP), 14.884-900 Jaboticabal, SP, Brazil.
Jesus Aparecido
JA
Ferro