Effect of Pasteuria penetrans endospore number and attachment method on Meloidogyne javanica root penetration and mass production of the bacteria in tomato plants Efeito do numero de endosporos de Pasteuria penetrans e do metodo de promocao da adesao sobre a penetracao de Meloidogyne javanica e producao da bacteria em tomateiro
Gomes, C.B.uer.; Grassi, D.F.eitas, L.; Ferraz, S.; Oliveira, R.D.Arc, D.L.ma.; Osorio, V.A.gayer.
Nematologia Brasileira. Dezembro; 262: 119-130
The effect of Pasteuria penetrans on penetration of Meloidogyne javanica in tomato roots was studied in the growth chamber. The tomato plants were inoculated with 1000 J2 carrying 0, 10, 30, 60 and 90 endospores attached to their cuticle by bubbling juvenile and endospore water suspensions. The inoculated plants were incubated for 10 days at 12-hour photoperiod and 27deg. C. The root system was collected and stained with acid fucsin to evaluate the number of juveniles that penetrated the roots. Attachment of 10 endospores/J2 reduced penetration by 50% compared to endospore-free J2, and was further reduced with increased number of attached spores. Subsequently, the attachment-promoting methods of air bubbling, shaking, centrifugation and being stationary were compared by calculating the coefficient of variation (CV) of attachment among juveniles in plastic tubes containing 15 mL suspension of 500 M. javanica J2 and endospores (1x105/mL). To evaluate the effect of attachment on the P. penetrans multiplication, plants in the greenhouse were inoculated with 1000 J2 carrying an average of 10 endospores each. The attachment was promoted through air bubbling, centrifugation or shaking. Seventy days after the inoculation, roots were collected and the egg and gall numbers were evaluated, before drying the roots to determine the dry weight and the number of endospores produced. A high variation in endospore number/J2 and number of galls and eggs per plant were observed using the air bubbling method. Even though the shaking method yielded more uniform attachment, the number of endospores produced was lower than that obtained in centrifugation and air bubbling methods (P<0.01).