An efficient barley and wheat colonization are achieved by Paraburkholderia tropica after seed inoculation

GARCIA, SABRINA SOLEDAD; BERNABEU, PAMELA; VIO, SANTIAGO ADOLFO; GALAR, MARÍA LINA; LUNA, MARIA FLAVIA

Foz de Iguazú

Simposio; XVI Symposium on Biological nitrogen Fixation with NON-LEGUMES ? IV Latinamerican Workchop of PGPR; 2018

EMBRAPA

Root colonization is a key factor in the successful interaction of Plant Growth Promoting Bacteria with plants. The study of bacterial population dynamic in plant tissues is a direct measure of their efficiency as colonizers. The aim of this study was to determine the colonization patterns of the PGPB Paraburkholderia tropica MTo-293 after its application to barley and wheat seeds to evaluate the efficiency of root colonization by the bacteria under gnotobiotic conditions using different approaches: i-culture-dependent techniques by counting bacterial colonies in suspension of disinfected and non-disinfected plant tissues and ii-culture-independent techniques by microscopic observations of plant tissues inoculated with marked strains with gfp and gus reporter genes, and by molecular biology techniques. The results of this work showed that: 1- P. tropica was able to colonize roots and stems of barley and wheat, both superficial and endophytically, and a similar behaviour was observed for both grasses. Root surface and endophytic bacterial population were moderately stable throughout the experiment, reaching values ranging from 7 to 10 and 4 to 5 log CFU/g of fresh weight, respectively. P. tropica was also able to colonize aerial tissues reaching endophytic stem populations greater than that found in roots (5 to 7 log CFU/g of fresh weight) for both grasses. 2- P. tropica could be localized by microscopy on roots of both grasses. It was observed an extensive surface colonization with rows and groups of bacteria on the junction of the epidermal root cells, on root hairs and on root tips. 3- It was also possible to detect P. tropica in disinfected and non-disinfected roots and stems tissues from barley and wheat plants using a nested-PCR as an alternative and easier way to determine the presence of the bacterium after inoculation of barley and wheat seeds. This work provides useful knowledge for the application of P. tropica as an inoculant in grasses.