Inoculation with Azospirillum lipoferum affects growth and gibberellin status of corn seedling roots

FULCHIERI M, LUCANGELI C, BOTTINI R

PLANT AND CELL PHYSIOLOGY

OXFORD UNIV PRESS

Lugar: Oxford; Año: 1993 vol. 34 p. 1305 - 1309

0032-0781

Maize (Zea mays L., hybrid Cargill 147) seedlings, grown in aseptic conditions, were inoculated with three strains of Azospirillum lipoferum (Al op 33, Al iaa 320, and ATCC 29708) or cultured in different concentrations of indol-3-acetic acid (IAA) or gibberellin A3 (GA3). After 48 h, root length, root surface area, root dry weight, and shoot dry weight were measured in all treatments. Gibberellin content was evaluated in selected roots of control and Azospirillum inoculated seedlings by gas chromatography-mass spectrometry-selected ion monitoring with the use of deuterated gibberellins as internal standards. The three strains of A. lipoferum, IAA (2 ng ml"1), and GA3 (40 to 400 pg ml"1) significantly enhanced root growth. Improvement of root hair growth and density was obtained mainly with A. lipoferum strain Al op 33 and GA3 40 pg ml"1. GA3 was identified by gas chromatography-mass spectrometry (by both, full scan and selected ion monitoring) in a free acid fraction from roots of the seedlings inoculated with A. lipoferum. In the roots of the non inoculated seedlings GA3 was found after hydrolysis of a fraction expected to contain glucosyl conjugates