Physiological and molecular changes associated with prevention of woolliness in peach following pre-harvest application of gibberellic acid

Peach [Prunus persica (L.) Batsch, cv. Chiripá] fruit harvested from plants sprayed with gibberellic acid (GA3), at the beginning (T1) and end of pit hardening (T2), kept under cold storage (CS) and controlled atmosphere (CA/CS), and from plants not sprayed with GA3 (Control) and kept under CS, were evaluated in terms of fruit size and mass, ripening, occurrence of woolliness and expression of supposedly related genes and proteins. Peaches not sprayed with GA3 and submitted to CS had a high incidence of woolliness, high mRNA abundance of vesicle transport genes and low mRNA abundance of genes associated with cell wall loosening, ethylene biosynthesis and heat shock proteins (HSPs). Early GA3 spraying did not delay ripening but induced an increase in fruit size. In addition, it also induced a climacteric rise and prevented the occurrence of woolliness after CS. Woolliness prevention as a result of either GA3 or CA/CS treatments resulted in higher abundance of mRNAs associated with cell wall metabolism, mitochondrial HSPs and 1-aminocyclopropane-1-carboxylic acid oxidase (ACCO). A unique GA3 response consisted of a high mRNA abundance of genes and/or proteins such as HSP40-1er, HSP40-2er, HSPCTR2, β-mannosidase (β-Man) and α-l-arabinofuranosidase (α-Ara).