EXTERNAL AND INTERNAL ROOT COLONIZATION OF MAIZE BY 2 PSEUDOMONAS STRAINS - ENUMERATION BY ENZYME-LINKED-IMMUNOSORBENT-ASSAY (ELISA)

Maize root colonization by two fluorescent Pseudomonas strains M.3.1. and TR335, isolated respectively from maize and tomato roots, were stu died in hydroponic conditions. Each bacterium was inoculated separatel y, and three different colonization areas were studied: nutrient solut ion, rhizoplane, and endorhizosphere. The two Pseudomonas strains esta blished large rhizosphere populations, and rhizoplane colonization of the entire root system was similar for both strains. However, strain M .3.1. colonized the endorhizosphere more efficiently than strain TR335 . Seminal root cuttings from the tip to the seed allowed the assessmen t of colonization of three different root areas (i.e., root cap and el ongation area, root-hair zone, and mature zone). Rhizoplane colonizati ons of all these three areas by M.3.1. were significantly the same, wh ereas strain TR335 colonized the rhizoplane of the root cap and elonga tion area more actively than the root-hair zone and mature zone. Popul ation size of the strain M.3.1. in the internal tissue of these areas was greater than that of strain TR335. Go-inoculations of the two stra ins indicated a stimulation of the population size of strain M.3.1. re gardless of root area studied, whereas population size of strain TR335 remained unchanged. These results demonstrated that external and inte rnal maize root tissues were colonized to a greater extent by a strain isolated from a maize rhizosphere than by one isolated from another r hizosphere.