Characterization and Pathogenicity of Soilborne Pathogens in Gloriosa superba: Effects of Single- and Multiple-Pathogen Coinfection on Disease Responses.

Glory lily (Gloriosa superba), an ornamental climbing plant, contains the bioactive compound colchicine, attracting attention from the pharmaceutical industry. However, soilborne pathogens have emerged as a serious threat to the cultivation of glory lily, leading to substantial economic losses in the southern parts of India. Among these, the three major pathogens are Macrophomina phaseolina, Fusarium oxysporum, and Agroathelia rolfsii, causing dry root rot (also referred to as charcoal rot), wilt, and stem rot, respectively. Here, we characterized these pathogens using morphological characteristics and phylogenetic analysis of DNA sequences related to the internal transcribed spacer of ribosomal DNA, calmodulin (CAL), and translation elongation factor 1-alpha (TEF-1α). Furthermore, in the pathogenicity tests, the inoculation of M. phaseolina alone resulted in lesions measuring 7.54 ± 0.01 mm on tubers and 90% seedling mortality. This severity was comparable to the simultaneous inoculation of all three pathogens, indicating the prominence of dry root rot among soilborne diseases. This study marks the first detailed investigation of soilborne pathogens combined infection in G. superba, contributing to the understanding of fungal disease complexity in medicinal plants.