Uncovering the Host Range for Maize Pathogen Magnaporthiopsis maydis

Abstract

The fungus <i>Magnaporthiopsis maydis</i> is a soil-borne, seed-borne vascular wilt pathogen that causes severe damage to sensitive <i>Zea</i> <i>mays</i> L. (maize) hybrids throughout Egypt, Israel, India, Spain, and other countries. It can undergo virulence variations and survive as spores, sclerotia, or mycelia on plant residues. Maize, <i>Lupinus</i> <i>termis</i> L. (lupine) and <i>Gossypium</i> <i>hirsutum</i> L. (cotton) are the only known hosts of <i>M. maydis</i>. Identification of new plant hosts that can assist in the survival of the pathogen is an essential step in restricting disease outbreak and spread. Here, by field survey and growth chamber pathogenicity test, accompanied by real-time PCR analysis, the presence of the fungal DNA inside the roots of cotton (Pima cv.) plants was confirmed in infested soil. Moreover, we identified <i>M. maydis</i> in <i>Setaria</i> <i>viridis</i> (green foxtail) and <i>Citrullus</i> <i>lanatus</i> (watermelon, Malali cv.). Infected watermelon sprouts had delayed emergence and development, were shorter, and had reduced root and shoot biomass. <i>M. maydis</i> infection also affected root biomass and phenological development of cotton plants but caused only mild symptoms in green foxtail. No <i>M. maydis</i> DNA was detected in <i>Hordeum</i> <i>vulgare</i> (barley, Noga cv.) and the plants showed no disease symptoms except for reduced shoot weight. These findings are an important step towards uncovering the host range and endophytic behavior of <i>M. maydis</i>, encouraging expanding this evaluation to other plant species.