Adeleke R.A., Mashiane R.A. and Bezuidenhout C.C.
Microbiology and Environmental Biotechnology Research Group Agricultural Research Council, Institute for Soil, Climate & Water 600, Belvedere Street, Arcadia, 0001, Pretoria; Unit for Environmental Science and Management, North West University-Potchefstroom campus, Private Bag X6001, Potchefstroom, 2520
Maize (Zea mays L.) expressing Bacillus thuringiensis (Bt) toxin has reduced the need for pesticides, however the toxin may affect the structure of plant associated microbes. Although there are benefits assigned to genetically modified plants, there is less information available in relation to the effect of the toxin to endophytes and their potential roles in plants. Endophytes are microorganism that dwell within the robust plant tissues by having a beneficial association with their host. The study aims at identifying the diversity and potential roles of cultivable endophytes associated with Bt and Non-Bt maize plants. Thirty-one isolates were obtained from the shoots of transgenic (Bt MON810) and its parental (Non-Bt) maize. The isolates were characterised according to their capacity to solubilise phosphate, nitrogen fixation, antifungal activity and IAA production. The genera found to be associated with both Bt and non-Bt maize were identified as Bacillus, Pantoea, Stenotrophomonas, Acinetobacter, Yersinia, with Serratia found only in Bt and Escherichia in Non-Bt maize. All strains were able to fix nitrogen and IAA production was detected in 16 strains with Pantoea sp. (Bt 2L) showing to be the highest producer. Furthermore, Yersinia sp. (NBt 10H* NBt 3L*), Bacillus sp. (NBt 10C2) and Serratia sp. (Bt1C) had high percentage inhibition against kernel pathogen F.verticillioides, signifying that endophytes found within the seeds of the maize are protecting the plants against pathogens. Acinetobacter sp. (Bt 9C**) obtained from the seeds showed to be the highest solubilisers with 51% efficiency. These finding suggest that the endophytes found in maize have potential to be good plant growth promoting bacteria and biological biocontrol, highlighting their importance in agriculture.