Nutrient requirement of conidial germination and characteristics of spore matrix for mango anthracnose fungus.
Weng F. Y., Chuang T. Y.
Author Affiliation: Department of Plant Pathology and Entomology, National Taiwan University, Taipei, Taiwan.
Plant Pathology Bulletin 6 : 17-24
Abstract : In a germination test with conidia of Colletotrichum gloeosporioides [Glomerella cingulata], a causal agent of mango anthracnose, addition of various carbon and nitrogen sources affected germination rate, hyphal growth and appressorium formation. The nutrient effect on conidial germination paralleled that on hyphal growth. Addition of 0.5% lysine, alanine and asparagine increased the conidial germination rate and promoted hyphal growth. However, the same concn of glycine, histidine and cysteine completely inhibited conidial germination. None of the tested carbon and nitrogen sources enhanced appressorium formation. When the washed spores were immersed in deionized water, the concn of protein and carbohydrate increased with increasing incubation time in an aqueous solution. Mycosporine was not detected in the solution. The spore matrix could enhance conidial germination and was able to stimulate anthracnose disease development on the young leaves of mango (var. Irwin). Symptoms developed faster in leaves inoculated with the mix of washed spores and conidial matrix than in those inoculated with washed spores alone. The stimulating effect of the matrix was heat stable. The autoclaved and crude matrices stimulated disease development, and so did wound inoculation. Addition of 0.5% lactose, asparagine and lysine into washed spores stimulated lesion expansion on young leaves.