Screening and characterization of GA3 producing Pseudomonas monteilii and its impact on plant growth promotion

Bacteria are abundantly present in the soil, interact with plant roots in the rhizosphere and enhance plant growth and development in certain instances. The plant growth promoting rhizobacteria (PGPR) develop a mutualistic relationship with the host plants and gives a benefit to them through N2 fixation by nitrogenase, nitrate reductase activity, siderophore production, and phytohormone secretion in the rhizosphere (Fulchieri et al., 1993; Cassán et al., 2001a, 2001b). Gibberellins production by PGPR promote the growth and yield of many crop plants, deconjugation of gibberellin-glucosyl conjugates exuded by the roots, or in the plant (Piccoli et al., 1997), and 3 hydroxylation by bacterial enzymes of inactive 3-deoxy gibberellins present in roots, to active forms such as GA1, GA3, and GA4 (Piccoli et al., 1996; Cassán et al., 2001a, 2001b). GAs have been identified and isolated from higher plants, fungi and bacteria. It was reported that 136 GAs from higher plants (128 species), 28 GAs from fungi (7 species), and only 4 GAs (GA1, GA3, GA4, and GA20) from bacteria (7 species) have been identified ISSN: 2319-7706 Volume 3 Number 5 (2014) pp. 110-115 http://www.ijcmas.com