The Carotenoid Esterification Gene BrPYP Controls Pale-Yellow Petal Color in Flowering Chinese Cabbage (Brassica rapa L. subsp. parachinensis)

Abstract

Carotenoid esterification plays indispensable roles in preventing degradation and maintaining the stability of carotenoids. Although the carotenoid biosynthetic pathway has been well characterized, the molecular mechanisms underlying carotenoid esterification, especially in floral organs, remain poorly understood. In this study, we identified a natural mutant flowering Chinese cabbage (Caixin, Brassica rapa L. subsp. chinensis var. parachinensis) with visually distinguishable pale-yellow petals controlled by a single recessive gene. Transmission electron microscopy (TEM) demonstrated that the chromoplasts in the yellow petals were surrounded by more fully developed plastoglobules compared to the pale-yellow mutant. Carotenoid analyses further revealed that, compared to the pale-yellow petals, the yellow petals contained high levels of esterified carotenoids, including lutein caprate, violaxanthin dilaurate, violaxanthin-myristate-laurate, 5,6epoxy-luttein dilaurate, lutein dilaurate, and lutein laurate. Based on bulked segregation analysis and fine mapping, we subsequently identified the critical role of a phytyl ester synthase 2 protein (PALE YELLOW PETAL, BrPYP) in regulating carotenoid pigmentation in flowering Chinese cabbage petals. Compared to the yellow wild-type, a 1,148 bp deletion was identified in the promoter region of BrPYP in the pale-yellow mutant, resulting in down-regulated expression. Transgenic Arabidopsis plants harboring beta-glucuronidase (GUS) driven by yellow (BrPYPY::GUS) and pale-yellow type (BrPYPPY::GUS) promoters were subsequently constructed, revealing stronger expression of BrPYPY::GUS both in the leaves and petals. Furthermore, virus-induced gene silencing of BrPYP significantly altered petal color from yellow to pale yellow. These findings demonstrate the molecular mechanism of carotenoid esterification, suggesting a role of phytyl ester synthase in carotenoid biosynthesis of flowering Chinese cabbage.

Xanthophyll esterases in association with fibrillins control the stable storage of carotenoids in yellow flowers of rapeseed (Brassica juncea)

“…pekinensis ; Fig. S1), which are ELTs involved in carotenoid ester biosynthesis (Yang et al ., 2021; Li et al ., 2022).…”

“…pekinensis; Fig. S1), which are ELTs involved in carotenoid ester biosynthesis (Yang et al, 2021;Li et al, 2022). We amplified and compared the DNA sequence of ORF2 (BjA02.PC1) between four accessions, including whiteflowered JG800, yellow-flowered L821 and L12-5, and the yellow-flowered inbred line LYS4 that has high sequence homology within the bja02.pc1 and bjb04.pc2 candidate regions of JG800.…”

“…Xanthophyll esterification is catalyzed by xanthophyll esterases (XES) or xanthophyll acyltransferase (XAT), which promote the transfer of broad fatty acid acyl donors to acceptors with the hydroxyl group of xanthophylls (Watkins et al ., 2019). Several XESs including PYP1 , IoXES , TeXES , XES1 , XES2 , and BrWF3 / BrPYP share homology with the Arabidopsis esterase/lipase/thioesterase (ELT) gene family, while being associated with xanthophyll esterification in flowers of tomato, Ipomoea obscura , marigold, carnation, and Chinese cabbage (Ariizumi et al ., 2014; Iijima et al ., 2020; Kishimoto et al ., 2020; Yang et al ., 2021; Li et al ., 2022). In addition, an XAT gene belonging to the Gly‐Asp‐Ser‐Leu (GDSL) esterase/lipase gene family has been verified to affect lutein esterification in bread wheat grain (Watkins et al ., 2019).…”

Cia Zeaxanthin Biosynthesis, OsZEP and OsVDE Regulate Striped Leaves Occurring in Response to Deep Transplanting of Rice

“…In the carotenoid metabolic pathway, intermediate metabolites are generally recognized to play a role in oxidation resistance or alleviating adverse effects in plants under abiotic stress [ 36 ]. Most carotenoids, such as zeaxanthin, antheraxanthin, and neoxanthin, are antioxidant-type pigments, which previous studies have reported play a certain role in dissipating excess light energy in photosynthetic organs.…”

Multi‐omics analyses reveal the importance of chromoplast plastoglobules in carotenoid accumulation in citrus fruit

“…These data suggest that the esterification of carotenoids may be important to this process via members of the esterase/ lipase/thioesterase (ELT) gene family. Xanthophyll esterases, that share homology with ELTs, are associated with xanthophyll esterification in flowers of tomato (Solanum lycopersicum), Ipomoea obscura, marigold, carnation, Chinese cabbage, and Brassica juncea (Ariizumi et al, 2014;Iijima et al, 2020;Li et al, 2022Li et al, , 2023. A xanthophyll acyltransferase of the Gly-Asp-Ser-Leu (GDSL) esterase/lipase gene family was involved in lutein esterification in bread wheat grain (Watkins et al, 2019).…”