Enhanced resistance to foliar fungal pathogens in carrot by application of elicitors
Back to previous page
| Authors: | Jayaraj, J; Rahman, M; Wan, A; Punja, ZK |
| Year: | 2009 |
| Journal: | Annals of Applied Biology 155: 71-80 Article Link (DOI) |
| Title: | Enhanced resistance to foliar fungal pathogens in carrot by application of elicitors |
| Abstract: | Treatment of greenhouse-grown carrot plants with salicylic acid (SA) (100 mu m), chitosan (0.02%) and the nutrient-chelate product Alexin (1%) followed 10 h later by inoculation with the necrotrophic fungal pathogens Alternaria radicina and Botrytis cinerea significantly reduced disease development 10 days after inoculation (d.a.i.) compared with control plants sprayed with water. The most effective treatment was chitosan, followed by Alexin and SA. Additional sprays of elicitors resulted in significantly lower disease development 25 d.a.i. Treated plants had elevated transcript levels of pathogenesis-related protein 1 (PR1), chitinase, lipid transfer protein (LTP), chalcone synthase, nonexpressor of PR1 and pathogenesis-related protein 5 (PR5) genes compared with control plants when assayed 10-70 h after treatment. The activity of peroxidase, polyphenoloxidase, phenylalanine ammonia-lyase, chitinase, beta-1,3-glucanase and lipoxygenase was significantly increased in elicitor-treated plants compared with control plants 12-72 h after treatment. Microscopic examination of treated leaves revealed reduced fungal growth and colonisation, 48 h after treatment, accompanied by fewer lesions at 120 h, compared with the control. Protein extracts from elicitor-treated plants reduced spore germination and germ tube elongation of the pathogens in vitro by 30-45%. Elicitor-treated plants accumulated higher amounts of total phenolics, 6-methoxymellin and H2O2 compared with the control. Both chitosan and Alexin induced responses similar to that of SA, suggesting that these elicitors may activate the salicylate pathway, leading to induction of defence genes, enzymes, phytoalexin and phenolics, which collectively reduced fungal colonisation. |
Please send suggestions for improving this publication database to
sass-support@sfu.ca.
Departmental members may update their publication list.