TRACKING BY CULTURE-DEPENDENT AND -INDEPENDENT TECHNIQUES, AND PLANTGROWTH?PROMOTION EFFECT OF Paraburkholderia tropica MTo-293 APPLIED ON TOMATO (Solanum lycopersicum L.)

VIO, SANTIAGO ADOLFO; CRESPO, JUAN MANUEL; BERNABEU, PAMELA; LUNA, MARIA FLAVIA; GALAR, MARÍA LINA

La Plata

Congreso; V Congreso Argentino de Microbiología Agrícola y Ambiental (CAMAYA); 2021

Asociación Argentina de Microbiología (AAM)

The Horticultural Belt of La Plata (CHP, Buenos Aires, Argentina) is one of the main production areas under cover with tomato as the first crop in order of importance. In recent years, the intensification of production has led to an excessive use of fertilizers and pesticides of chemical synthesis which have an undesired impact on food safety, human health and natural resources. Microbial bioinputs based on plant-growth?promoting bacteria (PGPB) have been considered key components of sustainable agriculture since they allow obtaining quality agri-food products adding value at source and reducing chemical use. PGPB exert beneficial effects on plant growth once rhizosphere, superficial or internal tissues (endophytes) have been efficiently colonized.Tomato cultivation is carried out in two stages: seedling in substrate and productive in soil after transplanting. Seedling transplant is a critical step with a great impact on crop development and yield. Achieving high-quality tomato seedlings is a goal to be pursued by using microbial bioinputs. PGPB adoption in horticulture is still scarce among CHP producers since PGPB applied on productive stage have shown limited success, mainly due to inefficient colonization.Paraburkholderia tropica has been characterized as an endophytic PGPB by in vitro and in vivo assays in different plants, and qualify as a promising bacterium for application as bioinput.Therefore, the aims of this work were the tracking of P. tropica MTo-293 Tcr throughout time in inoculated plants ?at sowing and before transplanting to pots? grown in substrate systems at growth chamber under controlled conditions, using culture-dependent and -independent techniques (nested PCR), and the evaluation of P. tropica effect on tomato plants by determining growth parameters on seedling and productive stage.Growth chamber results showed that:-P. tropica was able to efficiently colonize stem and root of tomato plants grown in both substrate systems: surface populations values were 104-105 CFU g−1fw in trays and 102-104 CFU g−1fw in pots 15 days postinoculation, and at around one order less the endophytic ones.-Nested PCR could be implemented to track P. tropica in populations lower than 102 CFU g−1fw.-Root and aerial part dry weight of 40 days seedlings grown in trays was higher in inoculated plants but this increase was only significant for roots (t-Test).-Biomass dry weight of plants inoculated before transplanting grown in pots was significantly higher than uninoculated and inoculated at sowing, by 25% and 38% for roots and aerial parts, respectively (ANOVA-Tukey).In greenhouse trials, P. tropica increased yields values from the first three harvested trusses: fruit weight per plant increased at about 27.4% and 29.8% in inoculated plants in 2017/18 and 2018/19 seasons, respectively, with significant differences in the last one (ANOVA-Tukey).This work contributes to the adoption of P. tropica as bioinput for a sustainable tomato production.