Reação de genótipos de soja quanto a resistência a Xanthomonas axonopodis pv. glycines e Pseudomonas savastonoi pv. glycinea

Abstract

Bacterial pustule and bacterial cresting caused by Xanthomonas axonopodis pv. glycines and Pseudomonas savastonoi pv. glycinea, respectively, are considered the main bacterial diseases of soybean crop worldwide. Where the main strategy for the control of these bacteriosis is through obtaining resistant genotypes. Thus, the present study aimed to: (i) evaluate the aggressiveness of Xanthomonas axonopodis pv glycines and Pseudomonas savastonoi pv. glycinea in greenhouse and controlled environment; (ii) select which bacterial isolate was the most aggressive; (iii) to evaluate the reaction of soybean genotypes regarding resistance to X. axonopodis pv. glycines and P. savastonoi pv. glycinea in controlled environment; (iv) selection of resistant genotypes in relation to bacteriosis, since there are few studies on this subject in the country. For the evaluation of the reaction of soybean genotypes regarding resistance to bacteriosis (Xanthomonas),forty genotypes were used, where detached trifolia were ( Pseudomonas) inoculated by leaf spray and distributed in GERBOX and stored in growth chamber-BOD in which both trials were performed in a completely randomized design with five repetitions, totaling 200 experimental plots.. (.) The severity of pustule and bacterial cresting were evaluated at 3, 6, 9, 12 days after inoculation, by a visual analysis, using scores from 0 to 5, and the Area Below the Disease Progress Curve (AACPD) was calculated. The data obtained were adjusted by the Generalized Least Squares (GLS) after the assumption of normality of the residues was observed by the Kolmogorov-Smirnov test at 0.05 significance. The UFU C35 isolates from Xanthononas axonopodis pv. glycines and UFU C3 of Pseudomonas savastonoi pv. glycinea was selected as the most aggressive isolates. All genotypes evaluated showed different levels of resistance to pathogens. The genotypes G2 (STWART), G14 (UFU L 196) and G15 (UFU L 586) were grouped as highly resistant, being an important source of resistance to bacterial pustule in soybean. For resistance to bacterial blight the genotypes, G13 (UFU L 526), G22 (UFU L 176), G38 (UFU L 88), G39 (UFU L 105), G40 (UFU L 200), G7 (NIDERA 7255), G1 (UFU TN 105 AP) and G2 (STWART), had the highest levels of resistance, being considered moderately resistant, and can be important sources of resistance to bacterial blight.