Carotenoid Accumulation and Carotenogenic Gene Expression during Fruit Development in Novel Interspecific Inbred Squash Lines and Their Parents

Abstract

Carotenoid levels and composition during squash fruit development were compared in Cucurbita moschata , Cucurbita maxima , and two lines of their interspecific inbred lines, namely, Maxchata1 and Maxchata2. Eight genes associated with carotenoid biosynthesis were analyzed by quantitative RT-PCR. The two squash species and their interspecific inbred lines exhibited different qualitative and quantitative carotenoid profiles and regulatory mechanisms. C. moschata had the lowest total carotenoid content and mainly accumulated α-carotene and β-carotene, as expected in a fruit with pale-orange flesh. Low carotenoid content in this species was probably due to the comparatively low expression of all genes investigated, especially PSY1 gene, compared to the other squashes. The predominant carotenoids in C. maxima were violaxanthin and lutein, which produced a corresponding yellow flesh color in mature fruit. The relationship between the expression of the CHYB and ZEP genes may result in almost equal concentrations of violaxanthin and lutein in C. maxima at fruit ripening. In contrast, their interspecific inbred lines principally accumulated lutein and β-carotene, leading to orange flesh color. The PSY1 gene exhibited higher expression levels at earlier stages of fruit development in the Maxchata lines, potentially triggering the increased carotenoid accumulation seen in these fruits. Likewise, the higher transcription level of CHYB gene observed in the two interspecific inbred lines might be correlated with high lutein in these hybrids. However, this study could not explain the observed β-carotene accumulation on the basis of gene expression.

Changes in carotenoid profiles and in the expression pattern of the genes in carotenoid metabolisms during fruit development and ripening in four watermelon cultivars

“…The reason is that ZEP and CHYB mediate, respectively, violaxanthin and lutein formation. Similar results were reported in squashes that ZEP and CHYB transcription levels might contribute to the violaxanthin and lutein accumulation, respectively (Nakkanong, Yang, & Zhang, 2012). It has been proposed that LCYE should be responsible for lutein synthesis in respect of carotenogenic pathway (Kim et al, 2013).…”

“…The present data show that although it is not the only one, control of gene expression at the transcriptional level is still a key regulatory mechanism controlling carotenoid accumulation in watermelon. The key roles of transcriptional regulation in controlling carotenoid formation and accumulation have been demonstrated in bitter melon, Capsicum annuum fruit, citrus fruit, Cucurbita pepo, kiwifruit, squash, and so on (Ampomah-Dwamena et al, 2009;Kato et al, 2004;Nakkanong et al, 2012;Obrero et al, 2013;Rodriguez-Uribe, Guzman, Rajapakse, Richins, & O'Connell, 2012;Tuan, Kim, Park, Lee, & Park, 2011). Thus, it seems to us that differential transcriptional regulation of carotenoid metabolic genes may be very important in determining the amount and type of specific carotenoids accumulated in different colour-fleshed fruits.…”

Comparative transcriptome analysis of two contrasting watermelon genotypes during fruit development and ripening

“…In the yellow-flesh cultivated watermelon “ZXG381”, the transcript variations in ZEP and CHYB strongly correlated with changes in the violaxanthin and lutein contents during ripening [26]. In squash, the upregulation of ZEP and CHYB transcription levels leads to violaxanthin and lutein production [34], respectively. These results suggested that the expression level of CHYB and ZEP might help maintain sustainable carotenes levels in COS. A further analysis and exploration of carotenes in COS is required to determine their significant correlation in COS. NCED is also involved in the catabolic pathway, which converts 9-cis-violaxanthin or 9-cis-neoxanthin to xanthoxin, an ancestor of ABA that is important for non-climatic fruit ripening [23, 35, 36].…”

α-Carotene and β-Carotene Content in Raw and Cooked Pulp of Three Mature Stage Winter Squash “Type Butternut”

“…Early expression of genes encoding enzymes is a critical factor to regulate the accumulation of carotenoids [4,5,6,7,8,9,10,11,12,13,14,15,16]. However, [17] in watermelon indicated that there is no correlation between carotenoid biosynthesis gene expression and specific carotene accumulation.…”

“…A reduction in the concentration of carotenoids that has been observed could be associated with the loss of solutes in the cooking water, due time and temperature induced changes in plant tissue during cooking [10,11,12,13,14,15,16,17,18,19,20,21]. At the time of harvest, the variety CosmosF1 did not show significant difference in dry matter content after microwave cooking ( p = 0.3911) or by the stage of commercial maturity of the fruits ( p = 0.6874) (Table 3).…”