Anatomy and Lignin Content in Relation to Resistance ofDactylis glomeratato Stagonospora Leaf Spot

Parallel veins of orchardgrass leaves were examined in relation to width of leaf spots incited by Stagonospora arenaria. Trials of 12 greenhouse-inoculated plants and 12 naturally infected, field-grown single-cross lines that ranged widely in mean leaf spot size gave similar results. Veins with large vascular bundles (enlarged metaxylem vessels present) alternated regularly with veins having small vascular bundles (enlarged metaxylem vessels absent). Vascular bundles usually were connected to the lower and/or upper epidermis by girders of lignified sclerenchyma and/or girders of thin-walled cells (...)