Induced systemic resistance in peanut

TONELLI, MARÍA LAURA; FURLAN, ANA LAURA; TAURIAN, TANIA; CASTRO, STELLA; FABRA, ADRIANA

Villa Carlos Paz

Congreso; VI Congreso Argentino de Microbiología General; 2009

Induced systemic resistance is a state of enhanced defensive capacity developed by a plant when is appropriately stimulated by a PGPB. A sequence of reactions enhance the expression of genes involved in plant defense, such as peroxidases (PO), glucanases, phenylalanine ammonia-liase (PAL), etc. Pseudomonas sp. BREN6 and Bacillus sp. CHEP5 were selected to evaluate their ability to induce systemic resistance in peanut performing split root experiments. Two weeks peanut plant roots were separated into two tubes with Hoagland solid medium, one of the tubes was inoculated with the bacteria (10 9 ufc/ml) or salicilic acid (1 mM and 10 mM) and, a week later, the other tube was challenged with the rhizoplane phythopathogen S. rolfsii. All the plants treated with S. rolfsii showed disease signs. However, P. sp. BREN6, B. sp. CHEP5 and salicilic acid enhanced shoot dry weight and B. sp. CHEP5 also enhaced root dry weight. The PO specific activity was increased in those plants inoculated with P. sp. BREN6, while PAL specific activity was increased in plants inoculated with P. sp. BREN6 and B. sp. CHEP5. Specific activity of β-1,3-glucanase was enhaced in all the plants challenged with S. rolfsii. With the aim to evaluate the expression of the gen that codified the enzyme PAL in peanut plants, we designed PALf and PALr primers and a 369 pb fragment was amplified by PCR. Pseudomonas sp. BREN6 and Bacillus sp. CHEP5 did not protect peanut plants from S. rolfsii deleterious effect, but as they promoted shoot growth and stimulated the activity of enzymes related to plant defense, we suggest that peanut plants can be systemically induced by these two bacteria.