Uso de isolados bacterianos no controle da podridão vermelha do sisal

Abstract

ABSTRACT 1 = The culture of Sisal (Agave sisalana) has economic prominence in Brazil due to its aptitude to grown under the unfavorable climatic conditions within the semiarid region. Brazil is the biggest word producer with the States of Bahia, Paraiba, Rio Grande do Norte and Ceará as the main domestic producers, with 96,2%, 3,25%, 0,34% and 0,16% of the national production respectively. Sisal’s fiber represents about 80 million dollars in exportations for the country, besides more than half a million direct and indirect jobs generated by its production chain. However, plat disease problems had caused the deterioration of this culture. Red rot disease, caused by the fungus Aspergillus niger, is considered as the main disease for this culture and responsible for its decline. Plants infected by the pathogen are unsuitable for fiber production and end up dying with the disease progress. Until now, there is no treatment known for the disease, which is lethal for the culture. Within this context, biological control is a feasible alternative and the use of bacteria is widely used to control plant pathogens. Thus, in this chapter were revised important aspects of the Sisal’s culture. Due to represent an extremely limiting factor to the development of the culture, the plant disease features are focused, with an emphasis to the Aspergillus Genera. In this work, different characteristics related to the biological control of plant diseases are also discussed, with a singular approach to the use of bacteria. ABSTRACT 2 = The culture of Sisal has economic prominence in Brazil due to its aptitude to grown under the unfavorable climatic conditions within the semiarid region. The country has the biggest world production with the State of Bahia being the nation’s main producer of Sisal. Red rot disease, caused by Aspergillus niger, is considered as the main cause of decrease of this culture within Brazil. There are no efficient control strategies against the disease. This work evaluated the potential control capabilities of 18 bacterial strains against red rot in Sisal. The isolates were able of inhibit mycelial growth, germination of spores and produced volatile compounds responsible by mycelial growth inhibition of A. niger. Using PCR technique, the gene bamC was detected in two antagonists (INV and BMH), associated with the synthesis of the antibiotic bacilomicin. Experiments showed that isolates INB2, ING2, INM12 and IND2 were the best control agents under green-house and field conditions. Fourteen isolates had a significant effect to control the disease in the field (IND2, INN2, INP2, INL2, INC2, INB2, INM2, ING2, INN12, INM12, INF2, INQ2, INU2 e INS2). Sequencing of the 16S region of the rRNA showed that these 14 isolates are species related to Burlkholderia plantarii, Burlkholderia glumae and Burlkholderia glandioli. The isolates INV and BMH were identified as Bacillus sp.