| Citrus is one of the most important crops with the biggest global demand in the fruit industry. This crop has been the object of much research because of the variety of diseases that affect it; been the bacterial diseases the ones that limit significantly its production. During the past years, three of the endophytic bacteria have been reported, these bacteria live exclusively in the xylem. One of the bacteria restricting to the xylem, thus causing millions of dollars of losses in the citrus crop, is Xylella fastidiosa, which causes citrus variegated chlorosis. In Brazil, X. fastidiosa has been reported to be responsible for 100% of loss of the citrus crop. The purpose of this research is to describe the bacterial population presence in the vascular system of some important citrus in Puerto Rico. Bacteria were isolated in common and semiselective culture media in order to detect the presence of bacteria in the vascular system. Eighty-six bacterial isolates from the vascular system were studied in regard to their morphology and some biochemical characteristics, and grouped into 11 strains. In citrus variety A-1 Ambersweet grafted in Swingle citrumelo rootstocks and B-3 Rhode red Valencia grafted in Cleopatra rootstocks, more bacteria were isolated compared to Hamlin variety D-2 Hamlin grafted in Carrizo rootstocks and D-4 Hamlin grafted in Sun chu sha rootstocks. By means of the BIOLOG RTM method, four bacteria strains were identified as: Bacillus sp. (two strains), Delftia acidovorans and Pseudomonas putida. Taxonomic positions were confirmed by using partial amplification and sequence of the gene 16S rRNA. The strains most frequently isolated were: Bacillus and Pseudomonas. Delftia acidovorans and Pseudomonas putida were found to have potential antagonisms toward some of the other bacteria under in vitro conditions. |
