Resumo

MADHAVAN, Srinivasan; PARANIDHARAN, Vaikuntavasan  e  VELAZHAHAN, Rethinasam. Foliar application of Burkholderia sp. strain TNAU-1 leads to activation of defense responses in chilli (Capsicum annuum L.). Braz. J. Plant Physiol. [online]. 2011, vol.23, n.4, pp. 261-266. ISSN 1677-0420.  http://dx.doi.org/10.1590/S1677-04202011000400003.

Induction of phenolics, peroxidase (PO), polyphenol oxidase (PPO), chitinase and thaumatin-like proteins (TLP) in leaves of chilli (Capsicum annuum L.) in response to foliar application with a biocontrol agent Burkholderia sp. strain TNAU-1 was studied. Chilli plants, when sprayed with Burkholderia sp. strain TNAU-1 showed increase in phenolic content one day after application and the maximum accumulation was observed seven days after treatment. Three new peroxidase isozymes (PO-1, PO-2 and PO-3) were induced in chilli leaves upon treatment with Burkholderia sp. strain TNAU-1. The activity of all the peroxidases was at the maximum level three days after treatment and subsequently decreased. Protein extracts obtained from Burkholderia sp. strain TNAU-1 treated plants exhibited a major polyphenol oxidase (PPO-1) one day after treatment. The activity of PPO-1 subsequently decreased, but continuously present throughout the experimental period of 15 days. Western blot analysis of protein extracts from Burkholderia sp. strain TNAU-1 treated chilli leaves revealed that two TLPs with sizes of 23 and 25 kDa and a chitinase with an apparent molecular weight of 28 kDa were induced three days after treatment.

Palavras-chave : Capsicum annuum; chitinase; induced resistance; peroxidase; phenolics; polyphenol oxidase; thaumatin-like protein.