Transcriptional changes associated with woolliness during fruit ripening in Prunus persica

During ripening of fruits stored under low temperatures, a number of physiological alterations which are manifested in a reduction of juice content take place, resulting in the apparition of woolly fruits. Modifications in cell wall structure during the ripening process are proposed to be key to determine the decreasing of juice content in woolly fruits. Under the assumption that changes in relative abundance of genes related to cell wall metabolism would be involved in woolliness development, in this work we present an analysis of the expression of multiple genes, which serves as an approximation to uncover the mechanisms behind this physiological alteration. The expression of 847 genes was examined using macroarrays hybridizations. Membranes were hybridized with 32P-labeled cDNAs synthesized from mRNAs of juice and woolly peaches. The results showed that 67.5% of the clones (n = 573) fulfilled all filter criteria and they were selected for sequence analysis. Our analysis indicate that 45% of transcripts which present a consistent expression level in all biological replicates are activated exclusively in juice condition, and only 15% in woolly fruits. In the resting 40% (transcripts common to both conditions,) only 5% presents an abundance increase in woolly samples. Keywords: Analysis of physiological disorder in peaches Macroarrays experiments were performed in six independent labeling/hybridization events (experimental replicates) of six distinct biological replicates (three juicy fruits and three woolly fruits). Therefore, a total of 36 membranes containing 960 spots that include the selected clones (847 cDNAs) plus control genes were obtained six intensity values/spot were recovered for each sample/fruit, and used to calculate the expression ratios.