Identification and characterization of pathogens causing saffron corm rot in China

Area of Science:

• Plant Pathology
• Microbial Ecology
• Agricultural Science

Background:

• Corm rot is a major disease affecting saffron production.
• Previous studies identified various fungal genera as potential pathogens, but the primary causal agent and infection source remained unclear.

Purpose of the Study:

• To identify the specific causal agent of saffron corm rot.
• To determine the main source of infection for this disease.
• To understand the microbial community dynamics associated with saffron corm rot.

Main Methods:

• Combined amplicon sequencing and traditional isolation techniques.
• Collected and analyzed diseased and healthy saffron corms and soil samples.
• Identified pathogenic isolates using morphological observation and phylogenetic analysis (ITS, Tef-1α, β-tubulin).
• Investigated the biological characteristics of the identified pathogen under varying environmental conditions (temperature, pH, carbon/nitrogen sources).

Main Results:

• Fusarium oxysporum was identified as the primary pathogen causing saffron corm rot.
• Microbial diversity decreased in diseased corms and soil compared to healthy ones.
• Relative abundance of Fusarium, Cadophora, and Fusicolla increased in diseased corms, while beneficial bacteria like Pseudomonas decreased.
• Diseased corms, rather than soil, were identified as the main primary infection source.
• Optimal growth conditions for F. oxysporum were determined as 25°C, pH 6, with sorbitol and peptone as preferred carbon and nitrogen sources, respectively.

Conclusions:

• Fusarium oxysporum is the causal agent of saffron corm rot in the Jiande region.
• Saffron corms serve as the primary source of infection, necessitating targeted management strategies.
• This research provides a foundational understanding for improved and efficient saffron corm rot management.