Induction of Rhizopus oryzae germination under starvation using host metabolites increases spore susceptibility to heat stress

Tidhar Turgeman, Nathan Kakongi, Avishai Schneider, Yakov Vinokur, Paula Teper-Bamnolker, Shmuel Carmeli, Maggie Levy, Christopher D. Skory, Amnon Lichter, Dani Eshel*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Sweetpotato is a nutritional source worldwide. Soft rot caused by Rhizopus spp. is a major limiting factor in the storage of produce, rendering it potentially unsafe for human consumption. In this study, Rhizopus oryzae was used to develop a concept of postharvest disease control by weakening the pathogen through induction of spore germination under starvation conditions. We isolated the sweetpotato active fractions (SPAFs) that induce spore germination and used them at a low dose to enhance spore weakening caused by starvation. Germination in SPAF at 1 mg/ml weakened the pathogen spores by delaying their ability to form colonies on rich media and by increasing their sensitivity to heat stress. The weakening effect was also supported by reduced metabolic activity, as detected by Alarmar Blue fluorescent dye assays. Spores incubated with SPAF at 1 mg/ml showed DNA fragmentation in some of their nuclei, as observed by TUNEL assay. In addition, these spores exhibited changes in ultrastructural morphology (i.e., shrinkage of germ tubes, nucleus deformation, and vacuole formation) which are hallmarks of programmed cell death. We suggest that induction of spore germination under starvation conditions increases their susceptibility to stress and, therefore, might be considered a new strategy for pathogen control.

Original languageEnglish
Pages (from-to)240-247
Number of pages8
JournalPhytopathology
Volume104
Issue number3
DOIs
StatePublished - Mar 2014

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