Induction of resistance in rice plants using bioproducts produced from Burkholderia pyrrocinia BRM 32113.

Abstract

Leaf blast is the main rice disease in the world causing significant losses in productivity. Blast integrate management (BIM) requires the use of genetic resistance, cultural practices, and chemical control, although for sustainable BIM, the insertion of biological agents may be the fourth component for. The objective of this work was to test three formulations of Burkholderia pyrrocinia (BRM32113) previously selected and to verify the effectiveness in resistance induction and blast control in rice. Two experiments were carried out, in a completely randomized design with three replications, in the greenhouse (E1 and E2). E1 aimed to select the best treatment for suppressing leaf blast severity and activating plant defense mechanisms. It was composed of 8 treatments: (1) formulated 11+ B. pyrrocina × Magnaporthe oryzae; (2) formulated 17+ B. pyrrocina × M. oryzae; (3) formulated 32+ B. pyrrocina × M. oryzae; (4) formulated 11 × M. oryzae; (5) B. pyrrocinia 17 × M. oryzae; (6) formulated 32 × M. oryzae; (7) B. pyrrocina × M. oryzae; (8) M. oryzae; (9) control (water). E2 aimed to investigate the effect of the best treatments, for the promotion of plant growth and suppression of leaf blast by calculating AUDPC. It was composed of 6 treatments: (1) formulated 11+ B. pyrrocina × M. oryzae; (2) formulated 32+ B. pyrrocina × M. oryzae; (3) formulated 11 × M. oryzae; (4) formulated 32 × M. oryzae; (5) B. pyrrocina × M. oryzae; (6) water. And after, we did two assays aimed to localize this biological agent after application at seed, soil, and rice plant. In E1, formulated 11+ B. pyrrocinia and 32+ formulated and B. pyrrocina were the best, suppressing leaf blast by up to 97% and providing the significant increase of the enzymes β-1,3-glucanase, chitinase, phenylalanine ammonia lyase, lipoxygenase, and salicylic acid at 24h and 48h after inoculation with M. oryzae. In E2, treatments formulated 11+ B. pyrrocinia, formulated 32+ B. pyrrocinia, and B. pyrrocina provided more significant increases in growth promotion and reduced area under disease progress curve. B. pyrrocinia was detected in the rice plant for 18days, predominantly in the root system (internal and external). The use of B. pyrrocinia formulations based on sugarcane molasses and glycerol can be an essential strategy for sustainable management. Although all the benefits come from these sustainable formulations, the adoption by commercial biological segment depends on an established formulation process. It seems that all the results showed here by this research will be readily assimilated by startups of the organic segment.