Carbohydrate involvement during infection of maize by Helminthosporium maydis

Germination and germ tube length of Helminthosporium maydis conidia did not exhibit much difference on fixed decolourized and living green leaves. However, appressoria, penetrations and colonizations were much less on decolourized host leaves and were enhanced significantly when sugars were added in the infection court. Few leached conidia germinated on the decolourized host leaves and appressoria, penetrations and colonizations effected on them by leached conidia were almost negligible. The presence of exogenous sugars and leaf leachates enabled the leached conidia to accomplish some penetrations and colonizations. Carbohydrate content of decolourized leaves and leached conidia was much less than the green leaves and non-leached conidia, respectively. Carbohydrates accumulated at the infection sites/green islands which also exhibited higher chlorophyll content.