Morpho-molecular characterization and pathogenicity of Geotrichum candidum causing potato rubbery rot: a new record...

As a staple vegetable crop, potato (Solanum tuberosum L.) has high nutritional value, affordability, and higher productivity across the world. However, a number of fungal diseases, significantly hamper productivity and quality during postharvest worldwide, including in India. In 2025, rubbery rot disease associated with potato was noticed in markets of Mullana and Ismailabad, Haryana, India. In total, 30 symptomatic potato samples were collected from different retailers and studied for associated causal agents. The isolated fungal species from 30 samples showed similar cultural and morphological features, therefore representative isolates PRR01 and PRR02 were subjected for molecular characterization. Multi-locus (ITS and tef-1 alpha) phylogenetic analysis of consensus sequence data of isolates PRR01 and PRR02 revealed that both isolates were >99.9% identical to Geotrichum candidum isolates CBS 116.28 and BAI; thus, confirming the identity. In pathogenicity test, the inoculated tubers exhibited a whitish colony on the surface, and the infected tissues emitted a putrid smell, after 10 days post incubation. The internal tissues of the potato became rubbery with no significant discoloration, after 30 days post incubation. Koch's postulates were also confirmed by re-isolating the fungal pathogens. To the best of our knowledge, this is the first report of rubbery rot disease of potato from India. These findings provide critical information for understanding the disease's etiology and offer a foundation for developing potential mitigation strategies to safeguard potato production.