Colonization and plant growth-promotion of tomato by Burkholderia tropica

BERNABEU PAMELA; PISTORIO MARIANO; TORRES TEJERIZO GONZALO; ESTRADA DE LOS SANTOS; GALAR M. L.; LUNA M F; BOIARDI J. L

SCIENTIA HORTICULTURAE

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2015 vol. 191 p. 113 - 120

0304-4238

Several diazotrophic Burkholderia species have been described to exhibit some activities involved in plantgrowth promotion and biological control. In this work seedlings of tomato plants were inoculated withthis bacterium in order to study colonization of different vegetal tissues and plant growth promotingability under greenhouse conditions. Tomato seedlings inoculated with Burkholderia tropica strain MTo-293 and two derivative strains containing the marker genes gusA and gfp, respectively (constructionsdescribed in this work), were grown under gnotobiotic conditions. Colonization was monitored both bycolony counting of bacterial suspensions from homogenized tissues with or without previous surfacedisinfection and by microscopic observation of entire plant tissues. In another set of experiments tomatoseedlings were inoculated with B. tropica MTo-293 for evaluation of tomato production under green-house conditions. Tomato yields were determined by quantifying total tomato production throughoutthe crop in two different seasons. B. tropica could be isolated from root surfaces (>7.0 log CFU g−1freshweight) and from surface-disinfected and disrupted roots (>5.0 log CFU g−1fresh weight) and stems (>4.0log CFU g−1fresh weight) of inoculated plants. Microscopic studies showed colonizing bacteria on roothairs, root tips, lateral root emergence sites, and stomata. In greenhouse experiments inoculated plantsshowed a consistent increase of both number and weight of fruits as compared to uninoculated controls.Although this enhancement in fruit production was only statistically significant for fruit weight in thefirst crop season, our results show a consistent tendency to a higher yield (5?15%) for the inoculatedtreatments also in the second year. These results show that seedling inoculation with B. tropica led toeffective root colonization of tomato plants followed by bacterial spreading to aerial tissues. This sig-nificant colonization was accompanied by an enhancement of tomato production in two different cropseasons.