Endogenous Ethylene and Color Development in the Skin of 'Pink Lady' Apple

By Suparna Whale, Z. Singh. 2007

91 citations recorded by the source corpus.

To elucidate the temporal relationship between endogenous ethylene and color development, changes in ethylene concentration, fruit color, pigments, and flavonoids were monitored at different intervals during the development and ripening of 'Pink Lady' apple (Malus · domestica Borkh.), commencing from 60 days after full bloom (DAFB) in 2002 to 2003, and 7 DAFB in the 2003 to 2004 season. Concentrations of chlorogenic acid, phloridzin, catechin, epicatechin, and quercetin glycosides were significantly higher (P # 0.05) during the early stages (7-60 DAFB) compared with the later stages ($60 DAFB) of fruit growth. During fruit development, concentrations of phloridzin, catechin, epicatechin, and quercetin glycosides decreased to low and stable levels. However, the concentration of anthocyanin (cyanidin 3-galactoside) increased during maturation and ripening ($168 DAFB), coinciding with a corresponding increase in percent red blush and endogenous ethylene concentration. Positive and significant correlations were found between ethylene and color development and between ethylene and total anthocyanin, but not the other flavonoid compounds. Ethylene therefore appears to be a key factor regulating anthocyanin biosynthesis and color development in 'Pink Lady' apple. However, the accumulation of other classes of flavonoids such as catechin, epicatechin, phloridzin, chlorogenic acid, and quercetin glycosides seems to be regulated independently of ethylene during fruit development and ripening. Traditionally, apples are grown in temperate climates. The development of new cultivars such as Pink Lady, which require less than 400 h at less than 7 � C (Mackay et al., 1994) to flower regularly, has made it possible to grow apples in the warmer parts of the world, including the Mediterranean regions, California, South Africa, and Australia. However, optimum fruit color development, particularly red blush at harvest, is still a major problem with 'Pink Lady' apples in these apple- growing areas. Poor and erratic color development often causes serious economic losses to the growers. Apple skin color results from the blending of chlorophyll, carotenoid, and anthocyanin pigments (Lancaster, 1992), with anthocyanins being primarily responsible for the red color (Lancaster, 1992). Apple skin also contains high concentrations of flavonols (quercetin 3-glycosides), flavanols (catechin, epicatechin, gallocatechin), dihydrochalcones (phloridzin), and hydroxycinnamic acid (chlorogenic acid) (Awad and de Jager, 2000; Lancaster, 1992). These flavonoids, including anthocyanins, form a group of plant secondary metabolites that are believed to contribute to human health with their antioxi- dant, free radical scavenging, anticarcinogenic, and antiinflam- matory properties (Rice-Evans et al., 1997). The phenolic composition of apples varies among cultivars (Napolitano et al., 2004), and the chemical composition and concentration of flavonoids and phenolic compounds is influenced by genetic variations, geographical location, and changes during the growing season and growth period (Tsao et al., 2003). It is therefore important to determine the pigment and flavonoid profile of new apple cultivars.

Subfields: Plant Science

View Paper: https://www.semanticscholar.org/paper/512f67ca2ff27812a1f7f55bff9e995cc5b1050b