Correlation Between Alkanes and Cracking in Different Sweet Cherries Varieties

Fruit cracking, in sweet cherries, is a complex phenomenon associated to rainfall before harvest causing significant economic losses. Some physical factors involved in cracking have been studied like water uptake by the fruit, osmotic factors, cuticle physical properties and anatomical aspects of fruit cells. Different studies show that an excessive water uptake through the fruit skin leads to fruit cracking. During the fruit development, waxes of the cuticle play an important role in water permeability. Nuclear magnetic resonance analysis (1H, and 13C), revealed that the fruits from the different sweet cherry varieties contain n-alkanes, mainly 29 carbons. GC/MS analysis of n-alkanes, revealed that fruit varieties with significantly major concentrations of nonacosane and total alkanes (Kordia, Regina and Lapins) were more tolerant to cracking than fruit varieties with lower levels of alkanes (Bing and Rainier).  Some candidate transcription factors and genes such as ketoacyl-CoA synthase, involved in the extension of long-chain fatty acids, were selected. Transcript levels determined by qPCR showed increase expression in cracking resistant varieties (Regina and Kordia) at the ripening time.

These results indicate a correlation between the quantity of n-alkanes with 29 carbons, gene expression and cracking tolerance in sweet cherry fruits. This difference could be a new important factor to explain the tolerance to cracking in fruits of different varieties.

Acknowledgments: CONICYT, FONDECYT/Regular Nº1120261