The Brazilian citriculture faces with severe problems concerning blooming and young fruit diseases, which cause crop losses and fruit depreciation for market. Such diseases are represented by the postbloom fruit drop (PFD) and by the black spot of citrus (CBS) whose control measures are predominantly through chemical products. However, the economical and environmental disadvantages associated with chemical treatments besides the increasing restrictions on the residuals of pesticides are strong factors that demand new control measures. Among them, the biological control stands out as being an important alternative. Former studies were carried out in laboratory and field conditions aiming at knowing the potentiality of Bacillus subtilis isolates in the control of the above mentioned diseases. Among the tested isolates, the ACB-69 showed the higher control efficiency. This project was undertaken in order to study, by means of AFLP molecular markers, the genetic diversity of 32 isolates of B. subtilis with the aim of discovering isolates as efficient as ACB-69, which could show a comparable control when tested under natural conditions of the disease occurrence. It was found from the results gathered here that: (i) the studied isolates of B. subtilis were grouped in the phylogram of a genetic distance, regardless of the precedence or host; (ii) the isolates ACB-69 and ACB-83, with potential for the control of the postbloom fruit drop, share the same ancestry, which is inferred by the methodology employed here; (iii) in biological terms, the isolate ACB-83 demands additional studies concerning its feasibility on the control of both diseases in field conditions.
Phyllosticta citricarpa; Citrus sinensis; AFLP
