CHARACTERIZATION OF APOPLAST-COLONIZING ENDOPHYTES FROM OILSEED RAPE LEAVES SHOWING ANTAGONISM TO CANOLA PHYTOPATHOGENS

ROMERO F.M.; ROSSI F.R.; GARRIZ A.; RUIZ O.A.

BARCELONA

Congreso; CONGRESO DE LA SOCIEDAD DE FISIOLOGÍA VEGETAL ESPAÑOLA; 2017

SOCIEDAD ESPAÑOLA DE FISIOLOGIA VEGETAL

Many endophytic bacteria colonize host tissues internally without causing damage or eliciting disease symptoms and in some cases promote plant growth and protect them against pathogens. This work aimed to characterize bacterial members of the apoplast-colonizing community of oilseed rape plants grown under conditions of commercial production, and to analyze their antagonistic properties against phytopathogens. Several bacterial endophytes were isolated from the apoplast of field-grown oilseed rape leaves. These isolates were co-cultured with different canola pathogens, such as the fungal pathogens Leptosphaeria maculans and Sclerotinia sclerotiorum and the bacterial pathogen Xanthomonas campestris, in order to evaluate their antagonistic properties in vitro. In this way, three isolates (Apo8, Apo11 and Apo12) were selected based on their ability to inhibit all pathogens tested in vitro. These isolates were identified by sequencing the ARNr 16S gene as members or the genus Pseudomonas, specially related to the specie P. viridiflava. In order to test these isolates for their ability to diminish the infection provoked by X. campestris, oilseed rape seeds were inoculated with bacterial endophytes and four weeks after sowing these plants were challenged with X. campestris. Thus, plants inoculated with Apo11 showed decreased pathogen propagation in comparison to mock-inoculated ones. Moreover, Apo11-inoculation induces the expression of defense genes involved in the salicylic acid and jasmonates signaling pathways. In addition to that, Apo11 inoculation produced a 50%-increment in fresh and dry weight of oilseed rape plants. This work allowed the identification of bacteria from apoplast of oilseed rape leaves able to inhibit growth of pathogens in vitro and to reduce disease symptoms caused by X. campestris when inoculated on canola plants. These features, along with their potential for plant growth promotion, render the above-mentioned isolate an interesting candidate for the development of biological formulations for growth promotion and control of canola diseases.