Bacterias solubilizadoras de Zn como promotoras del crecimiento en plantas de arroz y su contribución a la mitigación del estrés abiótico

SALAZAR, ANDY; MAIALE, SANTIAGO JAVIER; ALEGRE, MATÍAS; LLAMES, MARÍA EUGENIA; RODRÍGUEZ, ANDRÉS ALBERTO; WISS, BEATRIZ; MICHELINI, MARÍA CAROLINA; ROMERO, FERNANDO MATÍAS

Chascomús

Taller; 1er Taller Científico INTECH; 2023

INTECH

Rice in Argentina is mainly produced in Entre Ríos and Corrientes provinces. In Entre Ríos, the crop has limitations due to several stresses, among them stands out the Zn deficit. We proposed the study of zinc solubilizing bacteria isolated from the rice rhizosphere, as an alternative to increase the rice production in the area and to reduce chemical fertilization. Solubilizing bacteria were isolated on medium with an insoluble Zn source (Zn3(PO4)2) after enrichment in liquid medium. To confirm the solubilizing capacity, pH and soluble Zn were determined by the Zincon® method in culture medium. Phosphorus solubilization was also evaluated in NBRIP medium. Tolerance to low temperature was measure at 16°C. 15 isolates were selected from 99 bacterial isolates based on their ability to decrease the pH of the medium (pH2-6) and to show higher Zn3(PO4)2 solubilization (100-500ppm). Trough box PCR, 7 bacteria were identified out of the 15 isolates. The solubilizing capacity was also evaluated in both solid (qualitative) and liquid (quantitative) medium using ZnO as an insoluble source. In all cases, the ability to solubilize Zn was observed. The isolate 64 showed the highest values in ZnO solubilization (400-600 ug/ml); the bacteria 65 was the less effective with values between 100 and 300 ug/ml. Likewise, the bacterial ability to solubilize an insoluble source of phosphorus (Ca₃(PO₄)₂) was also detected and determined. For phosphorous solubilization, the highest rates were obtained for bacteria 64 (1.5-2). The 7 bacteria showed capability to grow at 16°C, and bacteria 50 and 64 were identified as the best tolerant bacteria, with colony diameters from 0.7 to 0.9 mm. These bacteria are currently being molecularly characterized and identified. Other plant-growth promotion traits such as indole and siderophore production are also being carried out. In conclusion, this work shows different bacteria with the capacity to solubilize Zn and P, that could be used as bioinoculants for rice cultivation to reduce the use of chemical fertilizers.