Characterization of embryogenic mango cultures selected for resistance to Colletotrichum gloeosporioides culture filtrate and phytotoxin.
Jayashankar S., Litz R. E.
Author Affiliation: Tropical Research and Education Center, University of Florida, 18905 SW 280 St., Homestead, FL 33031-3314, USA.
Theoretical and Applied Genetics 96 : 823-831
Abstract : Embryogenic nucellar cultures of two polyembryonic mango cultivars. Hindi and Carabao, were selected for resistance to the culture filtrate and phytotoxin of a virulent strain of Colletotrichum gloeosporioides [Glomerella cingulata], that was isolated from mango leaves. The cultures were recurrently selected either with progressively increasing concentrations of culture filtrate or by continuous challenge with the same concentration of either culture filtrate phytotoxin. Mycelium growth was inhibited when the pathogen was cocultured with the selected, resistant embryogenic cultures. Conditioned plant growth medium containing macerated resistant embryogenic cultures did not inhibit mycelium growth, confirming that extracellular antifungal compounds were involved in the defence response. Enhanced secretion of chitinase and glucanase was observed in the plant growth medium in which resistant embryogenic cultures and regenerated somatic embryos were grown in comparison with the controls.