Comparative Transcriptome Analysis Reveals Effects of Exogenous Hematin on Anthocyanin Biosynthesis during Strawberry Fruit Ripening

Abstract

Anthocyanin in strawberries has a positive effect on fruit coloration. In this study, the role of exogenous hematin on anthocyanin biosynthesis was investigated. Our result showed that the white stage of strawberries treated with exogenous hematin had higher anthocyanin content, compared to the control group. Among all treatments, 5 μM of hematin was the optimal condition to promote color development. In order to explore the molecular mechanism of fruit coloring regulated by hematin, transcriptomes in the hematin- and non-hematin-treated fruit were analyzed. A large number of differentially expressed genes (DEGs) were identified in regulating anthocyanin synthesis, including the DEGs involved in anthocyanin biosynthesis, hormone signaling transduction, phytochrome signaling, starch and sucrose degradation, and transcriptional pathways. These regulatory networks may play an important role in regulating the color process of strawberries treated with hematin. In summary, exogenous hematin could promote fruit coloring by increasing anthocyanin content in the white stage of strawberries. Furthermore, transcriptome analysis suggests that hematin-promoted fruit coloring occurs through multiple related metabolic pathways, which provides valuable information for regulating fruit color via anthocyanin biosynthesis in strawberries.

5-Aminolevulinic acid (ALA) biosynthetic and metabolic pathways and its role in higher plants: a review

“…For example, the fresh weight, fruit color and °Brix value of berries were enhanced by foliage application of 100 mg/L ALA, at flowering period in a 2-year-old grapevines plants (Vitis vinifera L.) (Watanabe et al 2006). During fruit growth and maturation, the coloring of pannexterna is due to anthocyanin biosynthesis and accumulation, which can be affected by light and plant hormone (including abscisic acid and naphthaleneacetic acid) (Jeong et al 2004;Vimolmangkang et al 2014;Li et al 2016). Genes in 'Fuji' apple skin, including enzyme genes (Pal, Chs and Ufgt) and transcription factors (Myb, bHLH and Wd40) related to anthocyanin biosynthesis, were all upregulated by ALA solution sprayed on the surface of fruits (Xie et al 2013;Chagné et al 2016).…”

Hydrogen peroxide as a mediator of 5‐aminolevulinic acid‐induced Na+ retention in roots for improving salt tolerance of strawberries

“…Therefore, one or more components in ALA metabolic pathways may be involved in the regulation of plant tolerance against salt stress. During fruit coloring, hematin (an exogenous heme) may improve anthocyanin accumulation in strawberries (Li et al ). Heme oxygenase‐1 (HO‐1) promotes anthocyanin accumulation in radish hypocotyls (Liu et al ).…”

Transcriptome profiling by RNA-Seq reveals differentially expressed genes related to fruit development and ripening characteristics in strawberries (Fragaria×ananassa)

“…In previous studies, RNA-Seq technology has been used to study fruit development and ripening ( Kang et al, 2013 ; Pillet et al, 2015 ; Li et al, 2016 ; Estrada-Johnson et al, 2017 ; Hartl et al, 2017 ). In this study, 91,790 unigenes were obtained.…”

“…FaTCP11 , FaPCL1-like , and FaSCL8 modulate the metabolism of strawberry flavonoids by regulating the expression of flavonoid pathway genes based on a transcriptome correlation network analysis of ripe strawberry fruits ( Pillet et al, 2015 ). Another application of transcriptome analysis in the strawberry anthocyanin biosynthesis pathway reveals that exogenous hematin promotes fruit coloring through multiple related metabolic pathways including anthocyanin biosynthesis and hormone signaling transduction, among others ( Li et al, 2016 ). In red-fruited and natural white-fruited strawberry varieties, transcriptome analysis showed that the genes related to the polyphenol biosynthesis pathway may interact with anthocyanin biosynthesis, flavor formation and fruit softening to regulate the fruit ripening process ( Hartl et al, 2017 ).…”