Accumulation of resistance signal substances in Guangfen No.1（ Musa spp. ABB） roots induced by Bacillus subtilis strain TR21

In order to reveal the relationship between systemic acquired resistance（ SAR） and systemic resistance in dwarf banana Guangfen No.1（ Musa sp. ABB） that induced by Bacillus subtilis strain TR21，the signal substances， NO，H2O2 and SA in the roots of Guangfen No.1 were detected. The seedlings were treated by four treatments as control （water inoculated in leaf axils），TR21 inoculated in leaf axils，Fusarium oxysporum f. sp. cubense strain FOC004microconidia inoculated on roots and challenge inoculation（ TR21 vaccinated leaf axils，24 h later FOC004 inoculated on roots），and then the SA，NO，and H2O2 content in roots were detected at 6 time points after 0 h，12 h，24 h，48 h，72 h and 96 h. Results showed that，both of the TR21 and FOC004 treatments avoided activating the plant to produce NO in early stage，but challenge inoculation activated the plant roots producing NO quickly and maintaining a high level for long time. TR21 and FOC004 avoided activating the plant generating H2O2 quickly in early stage，FOC004 only stimulated the H2O2 increasing markedly in roots at 24 h，but H2O2 in TR21 treated kept low level until 48 h and reached the highest level，the challenge inoculation treatment significantly stimulated the H2O2 increasing at the 12 h，and remained at a high level. TR21 treatment only promoted the production of free SA，but avoided bound SA observably in the early stage，FOC004 treatment inhibited the both free and bound SA production，but challenge inoculation motivated the plant producing bound SA for a long-term and stable level. To sum up，TR21 inoculation in leaf axils early could indeed help the Guangfen No.1 response the invasion of pathogen quickly，which would help the further development and field application of TR21.