Regulation of ethylene levels in canola (Brassica campestris) by 1-aminocyclopropane-1-carboxylate deaminase-containing Methylobacterium fujisawaense

Abstract

We report the presence of ACC deaminase in Methylobacterium fujisawaense and its lowering of ethylene levels and promotion of root elongation in canola seedlings under gnotobiotic conditions. To test a part of the previous model proposed for ACC deaminase producing bacteria with Methylobacterium, ACC levels and various enzyme activities were monitored in canola. Lower amounts of ACC were present in the tissues of seeds treated with M. fujisawaense strains than in control seeds treated with MgSO(4). Though the increased activities of ACC synthase in the tissue extracts of the treated seedlings might be due to bacterial indole-3-acetic acid, the amount of ACC was reduced due to bacterial ACC deaminase activity. The activities of ACC oxidase, the enzyme catalyzing conversion of ACC to ethylene remained lower in M. fujisawaense treated seedlings. This consequently lowered the ethylene in plants and prevented ethylene inhibition of root elongation. Our results collectively suggest that Methylobacterium commonly found in soils, as well as on the surfaces of leaves, seeds, and in the rhizosphere of a wide variety of plants could be better exploited to promote plant growth.

Methylobacterium phyllosphaerae sp. nov., a pink-pigmented, facultative methylotroph from the phyllosphere of rice

“…The acdS gene sequence of CBMB27 T was closely related to those of the type strains of M. oryzae (98.1 % similarity) and M. fujisawaense (92.5 %). The presence of ACCD in Methylobacterium and various bacterial genera has been reported (Madhaiyan et al, 2006;Penrose & Glick, 2001;Belimov et al, 2001). …”

“…Methylobacteria, as plant symbionts, utilize the methanol emitted from plants and, in turn, impart beneficial effects on plant growth through one or more mechanisms that include production of phytohormones like indoleacetic acid or cytokinins and vitamins (Basile et al, 1985;Koenig et al, 2002;Trotsenko et al, 2001), synthesis of enzymes such as urease or 1-aminocyclopropane-1-carboxylate deaminase (ACCD) that modulate plant growth (Holland & Polacco, 1992;Madhaiyan et al, 2006Madhaiyan et al, , 2007b and production of siderophores (Idris et al, 2004). Furthermore, they tolerate heavy metals and are able to reduce their phytotoxicity and improve plant growth (Idris et al, 2004;Madhaiyan et al, 2007a).…”

“…Samples were critical-point-dried, mounted on stubs, sputter-coated with gold/palladium and visualized by using a Hitachi S-2500C scanning electron microscope with a GEMINI column equipped with a field-emission electron source. The presence of the enzyme ACCD was determined by plate and quantitative assays as described previously (Madhaiyan et al, 2006). Cells of strain CBMB27 T were Gram-negative, aerobic, non-endospore-forming rods that were frequently branched and occurred singly or in rosettes on solid AMS medium and formed pink-to red-pigmented colonies.…”

Bacillus methylotrophicus sp. nov., a methanol-utilizing, plant-growth-promoting bacterium isolated from rice rhizosphere soil

“…A gnotobiotic growth pouch assay was performed to measure the degree of root elongation induced by ACC deaminase in tomato, canola and red pepper as these species are good representatives of ethylene sensitive plants (Glick et al, 1994;Li et al, 2000;Penrose & Glick, 2003;Ghosh et al, 2003;Madhaiyan et al, 2006Madhaiyan et al, , 2007b. Strain CBMB205 T possessed ACC deaminase activity, showed siderophore production and sulfur oxidation activity when tested by plate assays and produced negligible amounts of IAA (data For the analysis of cellular fatty acids, the novel strain was cultured in trypticase soy agar at 28 u C for 48 h. The fatty acids were extracted, derivatized to methyl esters and analysed by GC (6890; Hewlett Packard) using the Microbial Identification System (MIDI; Microbial ID) software package, according to standard protocols (Sasser, 1990).…”

Effect of Azospirillum brasilense and Methylobacterium oryzae Inoculation on Growth of Red Pepper (Capsicum annuum L.)

“…Thus, soil bacteria that inhabit plant roots and benefit plants by providing growth promotion are termed plant growth-promoting rhizobacteria (Bashan and Holguin 1997). Various rhizobacteria were reported to have many plant growth promoting abilities including N fixation, P solublization, production of plant growth hormones, GAs, cytokinins and auxins, and biological disease control (Madhaiyan et al, 2004(Madhaiyan et al, , 2006a(Madhaiyan et al, , 2007(Madhaiyan et al, , 2009Omer et al, 2004;Ryu et al, 2006).…”