Differential expression of genes involved in the biosynthesis and perception of ethylene during ripening of passion fruit (Passiflora edulis Sims). Plant Cell Physiology 39

An increase in the enzyme activity of 1-aminocyclopro-pane-1-carboxylic acid (ACC) synthase and ACC oxidase induces the evolution of ethylene during the ripening of pas-sion fruit. A much higher level of ethylene is produced in arils than in seeds or peels during ripening. The pattern of expression of two ACC synthase genes (PE-ACS1 and PE-ACS2), one ACC oxidase gene (PE-ACO1), and two ethyl-ene receptor genes (PE-ETR1 and PE-ERS1) revealed that the expression of these genes is differentially regulated. Ex-pression of PE-ACS1 and PE-ACO1 was enhanced during ripening and after ethylene treatment. However, promi-nent expression of PE-ACS1 was delayed compared to that of PE-ACO1. Much larger quantities of PE-ACS1 mRNA and PE-ACO1 mRNA were seen in arils than in seeds; this corresponds well with an increase in the amount of ethyl