Effects of heat treatment on enzyme activity and expression of key genes controlling cell wall remodeling in strawberry fruit

LANGER SILVIA E.; OVIEDO NATALIA C.; MARINA MARÍA; BURGOS JOSÉ L.; MARTÍNEZ GUSTAVO A.; CIVELLO PEDRO M.; VILLARREAL NATALIA M.

PLANT PHYSIOLOGY AND BIOCHEMISTRY

ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER

Año: 2018 vol. 130 p. 334 - 344

0981-9428

Modification of cell wall polymers composition and structure is one of the main factors contributing to texturalchanges during strawberry (Fragaria x ananassa, Duch.) fruit ripening and storage. The present study aimed toprovide new data to understand the molecular basis underlying the postharvest preservation of strawberry cellwall structure by heat treatment. Ripe fruit (cv. Aroma) were heat-treated in air oven (3 h at 45 °C) and thenstored 8 days at 4 °C + 2 days at 20 °C, while maintaining a set of non-treated fruit as controls. The effect of heatstress on the expression pattern of key genes controlling strawberry cell wall metabolism, as well as someenzymatic activities was investigated. The expression of genes proved to be relevant for pectin disassembly andfruit softening process (FaPG1, FaPLB, FaPLC, FaAra1, FaβGal4) were down-regulated by heat treatment, whilethe expression of genes being involved in the reinforcement of cell wall as pectin-methylesterase (FaPME1) andxyloglucan endo-transglycosilase (FaXTH1) was up-regulated. Total cell wall amount as well as cellulose,hemicellulose, neutral sugars and ionically and covalently bounded pectins were higher in heat-stressed fruitcompared to controls, which might be related to higher firmness values. Interestingly, heat stress was able toarrest the in vitro cell wall swelling process during postharvest fruit ripening, suggesting a preservation of cellwall structure, which was in agreement with a lower growth rate of Botrytis cinerea on plates containing cellwalls from heat-stressed fruit when compared to controls.