In vitro effects of caffeic acid upon growth of the fungi Sporisorium scitamineum

Abstract

Caffeic acid (CA) sometimes behaves as a potent phytotoxin affecting plant and fungi growth and physiology. The aim of the present study was to investigate whether CA at a concentration range similar to that found in sugarcane leaves, had any effect against different phases of Sporisorium scitamineum growth cycle. Leaf CA concentration from two different sugarcane cultivars, Mayari (My) 55-14, resistant, and Barbados (B) 42231, susceptible to smut, was chromatographically quantified by HPLC. A smut elicitor promoted an increase of CA concentration in the resistant cv. while no effect was produced in the susceptible one. The effect of CA upon S. scitamineum growth cycle showed to be dependent of both concentration and time. At 5.0 µg ml⁻¹, CA produced and inhibition of teliospore germination, haploid sporidia production and dikaryotic mycelium appearance. At 30 µg ml⁻¹, CA produced similar effects to these just described. Inhibition was more evident after 24 h or 28 h incubation of teliospores in CA solution than after 48 h. CA at 20 µg ml⁻¹ reduced both germination of teliospores and production of haploid sporidia but it had no significant effect on dikaryotic mycelium appearance after 24-h incubation.

Keywords:

• caffeic acid
• sugarcane
• smut
• teliospore
• haploid sporidia
• dicaryotic mycelium

Acknowledgments

This work has been supported by grants from Agencia Española de Cooperación con iberoamérica A/018020/08 (AECI) and Ministerio de Educación y Ciencia (Spain) BFU2006-14263. We gratefully acknowledge the excellent technical assistance of Mrs Raquel Alonso and Mr David Varela.