Identification of Anthocyanins-Related Glutathione S-Transferase (GST) Genes in the Genome of Cultivated Strawberry (Fragaria × ananassa)

Abstract

Anthocyanins are responsible for the red color of strawberry, they are a subclass of flavonoids synthesized in cytosol and transferred to vacuole to form the visible color. Previous studies in model and ornamental plants indicated members of the glutathione S-transferase (GST) gene family were involved in vacuolar accumulation of anthocyanins. In the present study, a total of 130 FaGST genes were identified in the genome of cultivated strawberry (Fragaria × ananassa), which were unevenly distributed across the 28 chromosomes from the four subgenomes. Evolutionary analysis revealed the expansion of FaGST family was under stable selection and mainly drove by WGD/segmental duplication event. Classification and phylogenetic analysis indicated that all the FaGST genes were clarified into seven subclasses, among which FaGST1, FaGST37, and FaGST97 belonging to Phi class were closely related to FvRAP, an anthocyanin-related GST of wildwood strawberry, and this clade was clustered with other known anthocyanin-related GSTs. RNAseq-based expression analysis at different developmental stages of strawberry revealed that the expression of FaGST1, FaGST37, FaGST39, FaGST73, and FaGST97 was gradually increased during the fruit ripening, consistent with the anthocyanins accumulation. These expression patterns of those five FaGST genes were also significantly correlated with those of other anthocyanin biosynthetic genes such as FaCHI, FaCHS, and FaANS, as well as anthocyanin regulatory gene FaMYB10. These results indicated FaGST1, FaGST37, FaGST39, FaGST73, and FaGST97 may function in vacuolar anthocyanin accumulation in cultivated strawberry.

Genomic Analysis of the Glutathione S-Transferase Family in Pear (Pyrus communis) and Functional Identification of PcGST57 in Anthocyanin Accumulation

“…The PcGST family was divided into 10 subfamilies, including lambda (L), dehydroascorbate reductase (DHAR), metaxin (M), tetrachlorohydroquinone dehalogenase-like (TCHQD), glutathionyl hydroquinone reductase (GHR), γ-subunit of the eukaryotic translation elongation factor 1B (EF1Bγ), Zeta (Z), Theta (T), Phi (F), and Tau (U). These were consistent with the GST subfamily in other species, including tomato, strawberry, and apple [ 21 , 28 , 36 ]. Among these subfamilies, the Tau subfamily contained the most PcGST genes (24), accounting for more than half of the total PcGST genes, followed by 11 PcGST genes in the Phi subfamily.…”

“…Initially, only three GST subfamilies were identified, including Theta, Tau, and Zeta [ 43 ]. Subsequently, the GST gene family was systematically and comprehensively analyzed, and increasing GST members were identified in various plant species, including maize [ 42 ], soybean [ 44 ], Arabidopsis [ 45 ], apple [ 36 ], strawberry [ 21 ], tomato [ 28 ], Citrus sinensis [ 46 ], kiwifruit [ 47 ], cotton [ 19 ], radish [ 22 ], wheat [ 48 ], and pepper [ 49 ]. The number of GST family members and the number of subfamilies vary in different plant species.…”

“…An ABCC-type transporter ( ZmMrp3 ) is required for anthocyanin transport to the vacuole in Zea mays [ 17 ], and two-fruit specificity anthoMATE1 (AM1) and AM3 proteins were also investigated in grapevine [ 18 ]. Recently, several studies revealed the involvement of GST genes in anthocyanin accumulation [ 11 , 19 , 20 , 21 , 22 ]. GST can combine with flavonoids to form a GST-flavonoid complex to protect flavonoids from oxidation or guide them into the central vacuole [ 23 ].…”

“…It was first demonstrated in Zea mays that ZmBZ2 encodes a GST protein, which is involved in the transportation of anthocyanins to vacuoles [ 30 ]. Subsequently, studies of GST genes related to anthocyanin transportation were reported in many other species, including PhAN9 in petunia [ 31 ], AtTT19 in Arabidopsis [ 32 ], CkmGST3 in cyclamen [ 33 ], VviGST4 in grape [ 34 ], PpGST1 in peach [ 20 ], FvRAP in strawberry [ 21 , 35 ], and MdGSTF6 in apple [ 36 ]. Although GST is involved in anthocyanin accumulation in many species, information on GST in European pear and the role of GST genes in pear coloration is still lacking.…”

Characterization and regulation mechanism analysis of ubiquitin-conjugating family genes in strawberry reveals a potential role in fruit ripening

“…The number of FaUBC genes is far more than the 45, 48, 52, 75, and 74 UBC genes isolated from the genome of Arabidopsis [ 32 ], rice [ 5 ], tomato [ 6 ], banana [ 7 ] and maize [ 33 ], which indicates that the UBC family expanded in strawberry. Gene duplication events such as whole genome duplication, tandem duplication, segmental duplication, and transposition have a remarkable role in the expansion of gene family members in genomes [ 34 ], and increasing evidences has shown that whole genome duplication are largely responsible for the expansion of gene families in cultivated strawberry, such as the GST, GMP and RALF gene families [ 35 – 37 ]. Additionally, the genome sizes of Arabidopsis, strawberry, rice, tomato, maize, and banana are ~ 125, ~ 240, ~ 466, ~ 466, ~ 900, ~ 2300, and 523 Mb, respectively.…”