Use of SF4c-tailocins to stimulate corn plants growth under water stress conditions

GAMBETTA, C; ASCONAPE, J; LOPEZ RAMIREZ, V; BARRIONUEVO, L; TRAVAGLIA, C; FISCHER, S

Rosario

Congreso; LIX Reunión Anual de SAIB; 2023

SAIB

Corn (Zea mays L.) is the most predominant cereal in Argentina, being Córdoba province the principal national producer. This crop is significant for economic activity, playing a fundamental role in crop rotation and as an input for several agro-food chains. Water deficit is one of the main problems that affect agriculture nowadays. The intense droughts recorded in the last years have caused a significant decrease in the production of summer crops. In this context, studies that tend to mitigate the effect of drought will mainly benefit the corn. The use of bacteriocins as a bioinput for application in agriculture is a topic that has begun to gain popularity in the last decade, especially for the biocontrol of phytopathogenic bacteria that cause economic losses in crops. New advances have allowed discover new property of bacteriocins, which is the ability to promote plant growth. However, in the world, only one bacteriocin has been evaluated as biostimulant of plants. Tailocins (phage tail-like bacteriocins) are high-molecular-mass protein complexes that resemble and are evolutionarily related to bacteriophage tails. The rhizospheric strain Pseudomonas fluorescens SF4c, belonging to our laboratory collection, produces tailocins with antimicrobial activity against phytopathogenic strains. This study aimed to evaluate SF4c-tailocins as a corn growth biostimulants under irrigation and water stress conditions. Corn seeds (SYN 897 Viptera 3-NK) were surface-sterilized and treated with 2 different doses of SF4c-tailocins: 102 and 103 arbitrary units per ml (AU ml-1). Then, the seeds were sown into pots containing peat: perlite (1:1) and kept in a greenhouse with controlled conditions (16h light, 28° C, 70% humidity, and 8h darkness, 18° C, 80% humidity). After 10 days, a differentiated irrigation regime was applied: 100% of the field capacity for optimal irrigation and 10% of the field capacity for water stress. At 45 days, plants were harvested. Dry biomass, stem diameter, and V8 leaf area were measured. For the statistical evaluation of the results, a univariate analysis (ANOVA) was performed for each parameter, with a posteriori Fisher LSD test, with a significance level of p < 0.05. Under optimal irrigation conditions, plants treated with tailocins (102 AU ml-1) had greater stem diameter (16%), V8 leaf area (27%), root dry weight (68%), and shoot dry weight (82%), compared with untreated plants. Under water stress conditions, SF4c-tailocins were able to alleviate the adverse effects of droughts. These results indicate that the application of SF4c-tailocins on seeds has a biostimulant effect on corn.