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POSTERS: Population Biology Genetics I

P-559 - Unraveling the population genomics of F. noneumartii: a pathogen with increasing impacts in California annual crop systems

Monday, August 4, 2025
4:30 PM - 5:15 PM HST
Location: Exhibit Hall 3
Abstract Text:

Fusarium stem rot and decline (FRD) is a newly characterized disease of tomato caused by at least two species within the Fusarium solani Species Complex (FSSC) clade 3. In California, Fusarium noneumartii is the most widespread and virulent species, detected in over 120 California tomato fields (2017-2022). This species also causes decline and/or dry rot diseases in several other annual crops including potato, sweet potato, hemp, and potentially sunflower—all commonly rotated crops. In addition, there appears to be at least one solely endophytic clone present in annual crops. The evolutionary and ecological origins of F. noneumartii remains enigmatic. In-planta tomato bioassays indicate variation in virulence among isolates associated with five crops (range Lesion Length: 0-133mm; Pval < 0.001) and among isolates derived from a single host (range Lesion Length: 0-93mm; Pval < 0.001). Functional genetic analyses suggest a highly clonal population, with many isolates residing within a single (of seven) somatic compatibility group. Genomic analyses are underway with 33 F. noneumartii isolates to evaluate further hidden subspecies diversity. Together, these studies can shed light how virulence, host of origin and somatic compatibility shape subspecies diversity specifically and the evolutionary trajectory of F. noneumartii more generally. This work provides a critical foundation for diagnostic tool development and crop rotation planning.