Independent Preharvest Applications of Methyl Jasmonate and Chitosan Elicit Differential Upregulation of Defense-Related Genes with Reduced Incidence of Gray Mold Decay during Postharvest Storage of Fragaria chiloensis Fruit.

Gabriela Saavedra,Pablo Figueroa,Carlos Figueroa,Eugenio Sanfuentes

doi:10.3390/ijms18071420

Gabriela Saavedra, Pablo Figueroa + Show 2 more

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https://doi.org/10.3390/ijms18071420

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Abstract

The Chilean strawberry (Fragaria chiloensis) fruit has interesting organoleptic properties, but its postharvest life is affected by gray mold decay caused by Botrytis cinerea. The effect of preharvest applications of methyl jasmonate (MeJA) or chitosan on the molecular defense-related responses and protection against gray mold decay were investigated in Chilean strawberry fruit during postharvest storage. Specifically, we inoculated harvested fruit with B. cinerea spores and studied the expression of genes encoding for the pathogenesis-related (PR) proteins β-1,3-glucanases (FcBG2-1, FcBG2-2 and FcBG2-3) and chitinases (FcCHI2-2 and FcCHI3-1), and for polygalacturonase inhibiting proteins (FcPGIP1 and FcPGIP2) at 0, 2, 24, 48, and 72 h post inoculation (hpi). Remarkably, MeJA- and chitosan-treated fruit exhibited a lower incidence of B. cinerea infection than the control-treated at 48 and 72 hpi. At the molecular level, both are efficient elicitors for priming in F. chiloensis fruit since we observed an upregulation of the FcBG2-1, FcBG2-3, FcPGIP1, and FcPGIP2 at 0 hpi. Moreover, a chitosan-mediated upregulation of FcPGIPs at early times post inoculation (2–24 hpi) and MeJA upregulated FcBGs (24–72 hpi) and FcPGIP1 at later times could contribute to reduce B. cinerea incidence by differential upregulation of defense genes. We concluded that preharvest applications of MeJA or chitosan had a long-lasting effect on the reduction of B. cinerea incidence during postharvest as well as an enhancer effect on the induction of PR and PGIP gene expression.

Highlights

The Chilean strawberry (Fragaria chiloensis (L.) Mill.) fruit has emerged as a new alternative for the global market of berries
We showed that independent preharvest applications of methyl jasmonate (MeJA) and chitosan to F. chiloensis fruit led to an increments in anthocyanin, antioxidant capacity, and lignin accumulation along with a delay in postharvest decay triggered by both elicitors [4]
We found that MeJA upregulated BG, CHI, and polygalacturonase-inhibiting proteins (PGIPs) genes with different patterns and levels in Chilean strawberry fruit during B. cinerea infection (Figures 2–4)

Summary

Introduction

The Chilean strawberry (Fragaria chiloensis (L.) Mill.) fruit has emerged as a new alternative for the global market of berries. It has interesting organoleptic properties, presenting a particular white color, good taste, and an intense aroma. Ex. Fr, a causal agent of gray mold disease, is a widely distributed necrotrophic fungus, and is one of the most destructive strawberry diseases worldwide. A causal agent of gray mold disease, is a widely distributed necrotrophic fungus, and is one of the most destructive strawberry diseases worldwide It can cause yield losses of up to 25% for non-protected strawberries [5] in spite of a certain degree of tolerance to fungal infection found in Chilean populations of F. chiloensis [6]. Due to the increasing resistance of fungal pathogens to fungicides and the growing concern of consumers over chemical residues, it is necessary to study alternative ways to better control postharvest diseases [8] through the reinforcement of natural plant defense systems

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