| Abstract |
Pseudomonas veronii MS1 and P. migulae MS2 have several
mechanisms of copper resistance and plant growth promoting
capability, and also can alleviate abiotic stress in plant by
hydrolysis of a precursor of stress ethylene, 1-aminocyclopropane-
1-carboxylic acid (ACC) by ACC deaminase. In 4-week pot
test for tomato growth in soil contained 700 mg/kg Cu,
inoculation of MS1 and MS2 significantly increased root and
shoot lengths, wet weight and dry weight of tomato plants
compared to those of uninoculated control. The inoculated
tomato plants contained less amounts of proline that can protect
plants from abiotic stress, and malondialdehyde, an oxidative
stress marker than those of control. ACC synthase genes, ACS4
and ACS6, and ACC oxidase genes, ACO1 and ACO4, both
involved in ethylene synthesis, were strongly expressed in Cu
stressed tomato, whereas significantly reduced in tomato
inoculated with MS1 and MS2. Also, a gene encoding a metal
binding protein metallothionein, MT2 showed similar expression
pattern with above genes. All these results indicated that these
rhizobacteria could confer Cu resistance to tomato plant under
Cu stress and allowed a lower level of Cu stress and growth
promotion. |
