Single Modified Food Cell Induced by Helicotylenchus pseudorobustus in Corn Roots.

Helicotylenchus pseudorobustus (Steiner) Golden is a common parasite of corn (Zea mays L.) in the midwestern United States (9). A 1983 survey of northern Italy indicated that H. pseudorobustus was the most common plant-parasitic nematode associated with corn. H. pseudorobustus is generally semiendoparasitic, feeding in the cortical parenchyma of corn roots and causing necrosis and disruption of cortical cells (7,9). Formation of "food cells" with dense cytoplasm and increased number of organelles without nuclear enlargement has been reported in barley (Hordeum sativum L.), oat (Arena sativa L.), and wheat (Triticum sp.) roots infected with H. digonicus Perry, H. pseudorobustus, and H. varicaudatus Yuen (5). Membranous networks around the stylet and loss of nucleolus without evidence of nuclear enlargement occurred in cortical cells of potato (Solanum tuberosum L.) roots infected by Scutellonema brachyurum (Steiner) Andrassy (8), another hoplolaimid nematode. This research note describes alterations in corn roots induced by feeding of H. pseudorobustus. Pregerminated Dekalb-XL-41 corn seeds were sown in bins containing sandy clay loam soil (23% clay, 11% silt, 62% sand, 4% gravel) infested with one n e m a t o d e / cm 3 soil of a population ofH. pseudorobustus collected at Rauscedo, in northern Italy. Plants were grown in a greenhouse at 22 + 4 C. Seedlings were harvested and root systems gently washed free of soil 20 days after sowing. Corn roots infected with nematodes were examined with a stereo-