Bactérias endofíticas no manejo da mancha e da pinta bacteriana e promoção de crescimento do tomateiro

Abstract

Diseases of bacterial etiology are among the main factors affecting tomato crop productivity. The spot and bacterial speck has been prominent in recent years, causing losses of 60% and 70%, respectively, when they occur in favorable conditions for their development. The control of bacterial diseases, besides being extremely difficult, requires the adoption of preventive measures, such as the acquisition of seeds and healthy seedlings, elimination of volunteer plants from the planting area, resistant cultivars and chemical products and copper, which are often effective in controlling disease. Thus, the biological control mediated by endophytic bacteria,can be an efficient management alternative to reduce the excessive use of pesticides in tomato crop. The objective of this work was to evaluate the potential of biocontrol of endophytic bacteria against tomato and bacterial spot of the tomato, in order to elucidate some mechanisms of action involved in the control of the two diseases, as well as to verify the potential of growth promotion promoted by them, in tomato plants. Fifteen endophytic bacteria were selected for the biological control tests of the above mentioned diseases and for growth promotion tests. The Ufla - 22 isolate was the most effective for controlling the bacterial spot and the Ufla - 285 isolate, the most effective in the control of bacterial pints, reducing disease severity by 45% and 56%, respectively. It was also possible to observe that these isolates presented resistance inducing effect, since they induced the increase of SOD gene transcription and provided increases in the activity of PAL, POX, SOD, APX and CAT defense enzymes in tomato plants of the susceptible cultivar Santa Clara. In addition, of the 15 isolates tested, it was observed that some were good growth promoters and substantially improved the physiological quality of tomato seeds. Thus, it can be suggested that the use of endophytic bacteria in the management of diseases of the tomato crop can be promising, since the biological control integrated to other management practices can reduce production costs and be effective in controlling the diseases mentioned above.