Bacillus amyloliquefaciens CN 307 e sua formulação comercial na quimiotaxia de Meloidogyne incognita

Abstract

The root-knot nematode, Meloidogyne incognita, causes significant damage to agriculture worldwide. Experiments were conducted in a greenhouse and at the Nematology Laboratory of the Federal University of Lavras, Minas Gerais, Brazil. Treatments consisted of applying the commercial product Auba® or the isolate B. amyloliquefaciens CN 307 to seeds of soybean (Glycine max L.), cv. M 6410 IPRO, common bean (Phaseolus vulgaris L.), cv. 2051, and corn (Zea mays L.), hybrid P 3707VYH C1. Chemotaxis assays showed that treated root exudates and roots exhibited a repellent effect on J2 nematodes, a result also observed when only the product or the isolate was tested. Biofilm formation occurred only in bean roots treated with the product. In beans, the commercial product and the isolate reduced the number of galls per gram of root by 31.24% and 42.96%, respectively, and the number of eggs per gram of root by 55.32% and 40%. In the second experiment, there was no significant reduction in the number of galls, but there were reductions in the number of eggs per gram of root of 59.78% with the product and 32.14% with the isolate. In soybeans, in the first experiment, there was no significant reduction in the number of galls per gram of root; however, the number of eggs was reduced by 64.18% with the product and 38.31% with the isolate. In the second experiment, the reductions in the number of galls per gram of root were 38.33% with the product and 27.80% with the isolate, with no significant effect on the number of eggs. Microscopic analysis with Raman spectroscopy indicated, in the treated roots, peaks associated with cellulose, xylan, and lignin, with a predominance of cellulose in beans and lignin in soybeans. The results indicate that the product and the isolate have potential for the biological management of M. incognita, acting through direct effects and biochemical alterations in root tissues.