A Preliminary Study for Identifying Genes Associated with Pellicle Development in Xinjiang Walnut (Juglans regia L.)

Abstract

Walnut (Juglans regia L.) is an important nut fruit crop mainly grown for its high nutritional and medicinal value. In walnut fruit, the pellicle is the main source of polyphenols (such as proanthocyanidins), which are natural bioactive compounds but also cause astringency and bitterness for walnut fruit consumption. However, the gene regulatory networks of phenolic biosynthetic pathways remain largely unknown in walnut pellicles. Here, we performed RNA sequencing (RNA-seq) to identify differentially expressed genes (DEGs) associated with pellicle development in walnut. In this study, seven developmental stages (8-, 9-, 11-, 13-, 15-, 17-, and 19-week after pollination) of ‘Xinwen179’ pellicle tissues were harvested to conduct further transcriptome-wide profiles. Via RNA-seq, we explored several key DEGs involved in the phenolic biosynthetic pathway, such as dihydroflavonol-4-reductase (DFR), leucoanthocyanidin reductase (LAR), anthocyanidin synthase (ANS) and anthocyanidin reductase (ANR), which are dynamically expressed at developmental stages of the walnut pellicle. Among them, ANR may directly contribute to proanthocyanidins accumulation during walnut development. Taken together, our preliminary investigation on DEGs associated with pellicle development will not only elucidate the gene regulatory networks of the phenolic biosynthetic pathway for pellicle development, but also contribute to the broad spectrum of RNA-seq data resources for further genetic improvement of walnut.

Historical spread routes of wild walnuts in Central Asia shaped by man-made and nature

“…This includes structural analysis, genetic map construction, and molecular marker-assisted breeding ( Liang et al., 2023 ; Yang et al., 2023 ; Zhou et al., 2023 ). However, until an updated reference genome is published, there is limited information available about the genome ( Jin et al., 2022 ; Luo et al., 2022 ). Sequencing the walnut genome has enabled us to identify SNPs efficiently.…”

Integrated metabolomic and transcriptomic dynamic profiles of endopleura coloration during fruit maturation in three walnut cultivars

“…The slightly bitter flavor of walnut kernels is related to the phenolic compounds they contain, which are more concentrated in the endopleura than in the kernel [ 35 ]. In addition, polyphenols have good antioxidant, anti-inflammatory, anti-mutagenic, and anti-free-radical properties, which can strengthen the immune system [ 36 , 37 ]. Recently, the composition of the yellow walnut endopleura and the molecular mechanism of its development in the walnut cultivar (‘LinZaoxiang’) have been reported [ 20 ].…”