Ethylene regulation of carotenoid accumulation and carotenogenic gene expression in colour-contrasted apricot varieties (Prunus armeniaca)

Abstract

In order to elucidate the regulation mechanisms of carotenoid biosynthesis in apricot fruit (Prunus armeniaca), carotenoid content and carotenogenic gene expression were analysed as a function of ethylene production in two colour-contrasted apricot varieties. Fruits from Goldrich (GO) were orange, while Moniqui (MO) fruits were white. Biochemical analysis showed that GO accumulated precursors of the uncoloured carotenoids, phytoene and phytofluene, and the coloured carotenoid, beta-carotene, while Moniqui (MO) fruits only accumulated phytoene and phytofluene but no beta-carotene. Physiological analysis showed that ethylene production was clearly weaker in GO than in MO. Carotenogenic gene expression (Psy-1, Pds, and Zds) and carotenoid accumulation were measured with respect to ethylene production which is initiated in mature green fruits at the onset of the climacteric stage or following exo-ethylene or ethylene-receptor inhibitor (1-MCP) treatments. Results showed (i) systematically stronger expression of carotenogenic genes in white than in orange fruits, even for the Zds gene involved in beta-carotene synthesis that is undetectable in MO fruits, (ii) ethylene-induction of Psy-1 and Pds gene expression and the corresponding product accumulation, (iii) Zds gene expression and beta-carotene production independent of ethylene. The different results obtained at physiological, biochemical, and molecular levels revealed the complex regulation of carotenoid biosynthesis in apricots and led to suggestions regarding some possible ways to regulate it.

Pomological and Nutraceutical Properties in Apricot Fruit: Cultivation Systems and Cold Storage Fruit Management

“…The third PC indicated 'Pellecchiella' as the genotype with the most balanced TSS/TA ratio. The analysis of carotenes (Table 3) showed that β-carotene was the most representative compound in accordance with other published results [27,39]. Among the two cultivars analyzed, 'Pellecchiella' showed the highest β-carotene content under both cultivation systems, and the organic fruits reached a higher amount than the integrated ones.…”

Change in anthocyanin concentrations in red apricot fruits during ripening

“…The cultivar A3751 was more abundant in both, anthocyanins and b-carotene than A3576. In a common orange apricot, Goldrich, the b-carotene content reached 20 mg kg À1 in the entire fruit, flesh and skin (Marty et al, 2005).…”

“…Apricot is an excellent source of b-carotene, the main carotenoid that confers the orange colour which is responsible for the colour of the un-blushed side in apricot fruits (Marty et al, 2005;Sass-Kiss, Kiss, Milotay, Kerek, & Toth-Markus, 2005).…”

Regulatory Role of Cystathionine-γ-Synthase and de novo Synthesis of Methionine in Ethylene Production during tomato Fruit Ripening

“…Induction of CGS gene expression by ethylene may also support other processes of tomato fruit maturation Ethylene acts as a hormone to promote expression of many genes, among them genes involved in ethylene synthesis (ACC synthase and ACC oxidase), fruit structure, carotenoid accumulation and production of aroma volatiles (Lincoln et al, 1993;Zegzouti et al, 1999;Alexander and Grierson, 2002;Marty et al, 2005). Ethylene may induce the expression of the CGS gene to promote its own synthesis when higher rates of ethylene synthesis are required.…”