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Uncovering host range for the maize pathogen Harpophora maydis

Ofir Degani: Migal – Galilee Research Institute

<div>The fungus<em> Harpophora maydis</em> is a soil-borne and seed-borne vascular wilt pathogen that causes severe damage to sensitive maize hybrids throughout Israel, Egypt, India and other countries. It can undergo pathogenic variations and survive as spores, sclerotia or mycelia on plant residues. Maize, <em>Lupinus termis</em> (lupine) and apparently cotton are the only known hosts of <em>H. maydis</em>. Identification of other plant hosts that can assist in the survival of the pathogen is an important step in restricting disease outbreak and spread. Here, a greenhouse pathogenicity trial series accompanied by Real-time PCR tracking confirmed the presence of the fungus’ DNA inside the roots of cotton plants grown on infested soil. Moreover, we identified the presence of <em>H. maydis</em> in <em>Setaria viridis</em> and in watermelon (Malali cv.). Infected watermelon plants had delayed emergence and development, were shorter, and had reduced root and shoot biomass. <em>H. maydis</em> infection damaged the root biomass and phenological development of cotton plants but caused only mild symptoms in <em>S. </em><em>viridis</em>. In liquid minimal medium, <em>H. maydis</em> growth was enhanced in the presence of maize or cotton root powder. While watermelon root powder had a minor influence on fungal dry weight, it caused a dramatic increase in pathogen laccase production. These findings are an important step towards uncovering the host range and endophytic behavior of <em>H. maydis</em>, and encourage expanding this evaluation to other plant species.</div>