Postharvest Treatment of Hydrogen Sulfide Delays the Softening of Chilean Strawberry Fruit by Downregulating the Expression of Key Genes Involved in Pectin Catabolism.

Sebastian A Molinett,Felipe A Sáez,Juan F Alfaro,Carlos R Figueroa,MaríA A Moya-LeóN,Sebastian Elgueta

doi:10.3390/ijms221810008

Abstract

Hydrogen sulfide (H2S) plays several physiological roles in plants. Despite the evidence, the role of H2S on cell wall disassembly and its implications on fleshy fruit firmness remains unknown. In this work, the effect of H2S treatment on the shelf-life, cell wall polymers and cell wall modifying-related gene expression of Chilean strawberry (Fragaria chiloensis) fruit was tested during postharvest storage. The treatment with H2S prolonged the shelf-life of fruit by an effect of optimal dose. Fruit treated with 0.2 mM H2S maintained significantly higher fruit firmness than non-treated fruit, reducing its decay and tripling its shelf-life. Additionally, H2S treatment delays pectin degradation throughout the storage period and significantly downregulated the expression of genes encoding for pectinases, such as polygalacturonase, pectate lyase, and expansin. This evidence suggests that H2S as a gasotransmitter prolongs the post-harvest shelf-life of the fruit and prevents its fast softening rate by a downregulation of the expression of key pectinase genes, which leads to a decreased pectin degradation.

Highlights

The Chilean strawberry [Fragaria chiloensis (L.) Mill.] is a native species from SouthAmerica and the maternal progenitor of the commercial strawberry Fragaria × ananassaDuch. [1]
We study the effect of Hydrogen sulfide (H2 S) treatment on the metabolism of cell wall polysaccharides, i.e., pectin and hemicellulose catabolism and the implications on the expression of genes encoding for enzymes involved in cell wall modification during postharvest-associated fruit softening
The results reported in this work have shown that H2 S treatment delayed softening on fumigated F. chiloensis fruit, which remained significantly firmer than untreated fruit throughout the monitored days (Figure 3A)

Summary

Introduction

The Chilean strawberry [Fragaria chiloensis (L.) Mill.] is a native species from SouthAmerica and the maternal progenitor of the commercial strawberry Fragaria × ananassaDuch. [1]. F. chiloensis fruit is emerging as a new model for studying several ripening-associated processes in strawberries [5,6], such as anthocyanin biosynthesis and plant cell wall disassembly [7,8]. The ripening-associated softening of fleshy fruit has been largely described as a direct consequence of enzyme-mediated cell wall disassembly [10]. Events such as depolymerization and solubilization of hemicelluloses and pectins within the cell wall often occur in many fleshy fruits, including strawberry [7]. The higher softening rate of F. chiloensis fruit has been associated with a high expression level of the PG gene during fruit ripening [12]. Several reports indicate that pectin metabolism has a significant role in strawberry fruit firmness [7,13,15,16] rather than hemicellulose or cellulose metabolism [17]

Methods

Results

Discussion

Conclusion