Ethylene-regulation of fruit softening and softening-related genes in peach

Abstract

To investigate the role of ethylene in peach fruit softening during ripening, stony hard peach fruit, in which ethylene production is suppressed during ripening, were treated with various concentrations of ethylene. There was no noticeable decrease in flesh firmness without ethylene treatment, while applied ethylene, in the range 0.1-100 ml l 21, resulted in fruit softening. Furthermore, the fruit softened more rapidly when the applied ethylene concentration was higher. When ethylene treatment was interrupted, the degree of softening was greatly reduced. These results indicated that continuous ethylene treatment was required for the initiation and progression of fruit softening and that ethylene concentration is also an important factor in regulating the rate of softening. Eight genes, which putatively encode cell wall metabolism-related proteins, were investigated for mRNA accumulation patterns in the two different softening phenotypes of melting and stony hard peaches. All of the mRNAs investigated accumulated in fruit of the melting-flesh 'Akatsuki' during ripening. By contrast, in the stony hard-flesh 'Manami', the mRNAs for a putative endopolygalacturonase (PpPG), an a-L-arabinofuranosidase/b-xylosidase (PpARF/XYL), and an expansin (PpExp3) showed either much lower levels or did not accumulate, and were identified as softening-related genes. Interruption of ethylene treatment indicated that these genes were regulated at the transcriptional level, and quickly responded to the presence or absence of ethylene before the softening response occurred, suggesting that ethylene directly regulates the transcription of these softening-related genes. These results suggested that cell wall metabolism, causing a rapid loss of firmness in peach fruit, may be controlled by ethylene at the transcriptional level.

Effect of growth regulators on 'Brookfield' apple gas diffusion and metabolism under controlled atmosphere storage

“…This indicated that these growth regulators changed the natural fruit ripening process, which could result in early ethylene peak and, consequently, in a faster fruit ripening after harvest, once ethylene initiates a series of biochemical reactions that leads to fruit ripening and senescence. Moreover, it stimulated cellular metabolism changes which are responsible for regulating fruit softening (Hayama et al, 2006). Low IEC was found in fruit subjected to 1-MCP, ABS, AVG + ABS, and AVG + 1-MCP, at the opened cooling rooms and after six days of shelf life.…”

Fisiología y bioquímica de la maduración del fruto de durazno [<i>Prunus persica</i> (L.) Batsch]. Una Revisión

“…Hayama et al (2006) determinaron que frutos con aplicación de etileno en el rango de 0,1-100 μL L -1 mostraron ablandamiento, mientras que los frutos que no se trataron con etileno no mostraron reducciones notables en su firmeza, esto les permitió concluir que la presencia y concentración de etileno es indispensable para la iniciación, avance y regulación de la tasa de ablandamiento de los frutos.…”

Inheritance of Flesh Texture in Peach and Effects of Ethylene Treatment on Softening of the Stony Hard Peach

“…They concluded that inhibition of endogenous ethylene production in the stony hard peach fruit was due to the suppressed expression of Pp-ACS1 mRNA. Hayama et al studied the expression of genes encoding cell-wall modification enzymes in the stony hard peach with and without ethylene treatment, and identified three genes as related to softening in the 12 . These reports show that the stony hard variety is an ideal mutant for studying the relationship between fruit softening and ethylene.…”