Transporte de Xanthomonas vesicatoria de sementes para plântulas e mudas de tomate

Abstract

Transport of Xanthomonas vesicatoria from seeds to seedlings and to plants of tomatoTransmission of Xanthomonas vesicatoria by seeds is one of the major sources of inoculum for development of epidemic bacterial spot. The aim in this work was elucidating the process of infection and colonization of tomato seeds and seedlings by these bacteria. Three experiments were carried out using X. vesicatoria, ENA 4463 isolate, and tomato seeds from Santa Clara Miss Brasil cultivar. Seeds were inoculated using vacuum or by injection of bacterial suspension in the region of the placenta of green fruits. Sowing was done in Gerbox boxes, aluminum or Styrofoam trays (128 cells) containing germitest paper, sand or commercial substrate for seedlings, respectively. Seedlings in Gerbox were assessed along six days by the quantification of bacterial population associated to different organs, through direct and indirect isolation on NA medium. In sand and commercial substrate, assessments were carried out until 30 days using the same procedures. Bacteria was easily isolated from the coat along the first six days, and from radicles, hypocotyls and cotyledon leaves just after the organs appearance, at two or three days after sowing, respectively. Maximum population of Xanthomonas vesicatoria was observed at 48 hours after sowing at the time of radicle protrusion. In sand and commercial substrate experiments, the bacteria colonized all plant organs and this process occurred as they arose. These bacteria can survive as resident at roots, epicotyls, cotyledon and definitive leaves until, at least, 30 days after sowing, not necessarily causing symptoms.

Occurrence of Pseudomonas syringae pv. garcae in coffee seeds

“…glycinea, and also reported symptoms of this disease in plants derived from these seeds, when exposed to ideal conditions for infection. Thus, even if the pathogen cannot be visually detected in seeds, as occurred in this study, seeds can be effective in disseminating plant bacterial diseases (Parashar and Leben, 1972;Silva et al, 2002;Romeiro, 2005;Corrêa et al, 2008;Silva et al, 2013).…”

“…Thus the occurrence, distribution pattern and progress of epidemics depend on the origin of the initial inoculum, which is often seed borne (Romeiro, 2005;Brasil, 2009). Several studies have provided evidence that seeds harbor diverse microbial flora, both on the surface and in the internal tissues (Saettler et al, 1989;Bacilio-Jiménez et al, 2001;Romeiro, 2005;Goto, 2012;Silva et al, 2013), and proliferation is stimulated in early germination (Simon et al, 2001;Nelson, 2004). In the case of plant pathogens, the inoculum can be transmitted by seeds to plants in both nursery and field.…”

“…Even harbored in the outer seed integument, the inoculum of some bacterial species can cause infection in plants (Guthrie, 1970;Silva et al, 2002;Corrêa et al, 2008). Silva et al (2013) reported transmission and infection by Xanthomonas vesicatoria from seed integument to new shoots of tomato seedlings (Solanum lycopersicum L.). Although seed transmission rate is low (Saettler et al, 1989;Carmo et al, 2004), seeds can act as efficient vectors for spreading bacteria (Romeiro, 2005) if the initial inoculum is introduced into growing areas (Carmo et al, 1996;Carmo et al, 2004;Romeiro, 2005;Silva et al, 2013).…”

“…Silva et al (2013) reported transmission and infection by Xanthomonas vesicatoria from seed integument to new shoots of tomato seedlings (Solanum lycopersicum L.). Although seed transmission rate is low (Saettler et al, 1989;Carmo et al, 2004), seeds can act as efficient vectors for spreading bacteria (Romeiro, 2005) if the initial inoculum is introduced into growing areas (Carmo et al, 1996;Carmo et al, 2004;Romeiro, 2005;Silva et al, 2013). For example, the transport of bacteria from complex X. vesicatoria by tomato seeds (S. lycopersicum) is a major mechanism of survival and spread of the pathogen (Carmo et al, 2004;Jones et al, 2004).…”

Scientific Opinion on the pest categorisation of Xanthomonas campestris pv. vesicatoria (Doidge) Dye

“…Pepper seeds were found to be more frequently contaminated than tomato seed lots (Black et al, 2001). Contaminated seeds lead to infection of seedlings; therefore, bacteria colonise the whole plants and can survive as residents on roots, epicotyls, cotyledons and leaves at least 30 days after sowing without necessarily causing symptoms (Silva et al, 2013).…”