Novel insights of ethylene role in strawberry cell wall metabolism

VILLARREAL NATALIA M.; MARINA MARÍA; NARDI CRISTINA F.; CIVELLO PEDRO M.; MARTÍNEZ GUSTAVO A.

PLANT SCIENCE

ELSEVIER IRELAND LTD

Lugar: Dublin; Año: 2016 vol. 252 p. 1 - 11

0168-9452

Due to its organoleptic and nutraceutical qualities, strawberry fruit (Fragaria x ananassa, Duch) is a worldwide important commodity. The role of ethylene in the regulation of strawberry cell wall metabolismwas studied in fruit from Toyonoka cultivar harvested at white stage, when most changes associated withfruit ripening have begun. Fruit were treated with ethephon, an ethylene-releasing reagent, or with 1-methylcyclopropene (1-MCP), a competitive inhibitor of ethylene action, maintaining a set of non-treatedfruit as controls for each condition. Ethephon treated-fruit showed higher contents of hemicelluloses, cellulose and neutral sugars regarding controls, while 1-MCP-treated fruit showed a lower amount of thosefractions. On the other hand, ethephon-treated fruit presented a lower quantity of galacturonic acid fromionically and covalently bound pectins regarding controls, while 1-MCP-treated fruit showed higher contents of those components. We also explored the ethylene effect over the mRNA accumulation of genesrelated to pectins and hemicelluloses metabolism, and a relationship between gene expression patternsand cell wall polysaccharides contents was shown. Moreover, we detected that strawberry necrotrophicpathogens growth more easily on plates containing cell walls from ethephon-treated fruit regarding controls, while a lower growth rate was observed when cell walls from 1-MCP treated fruit were used asthe only carbon source, suggesting an effect of ethylene on cell wall structure. Around 60% of strawberrycell wall is made up of pectins, which in turns is 70% made by homogalacturonans. Our findings supportthe idea of a central role for pectins on strawberry fruit softening and a participation of ethylene in theregulation of this process.