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Article|07 Jan 2020|OPEN
Diversity of metabolite accumulation patterns in inner and outer seed coats of pomegranate: exploring their relationship with genetic mechanisms of seed coat development
Gaihua Qin1,2, Chunyan Liu1,2, Jiyu Li1,2, Yongjie Qi1,2, Zhenghui Gao1,2, Xiaoling Zhang1, Xingkai Yi1, Haifa Pan1, Ray Ming3,4 & Yiliu Xu1,2,
1Key Laboratory of Genetic Improvement and Ecophysiology of Horticultural Crops, Anhui Province, Horticultural Research Institute, Anhui Academy of Agricultural Sciences, Hefei 230001, China
2Key Laboratory of Fruit Quality and Development Biology, Anhui Academy of Agricultural Sciences, Hefei 230001, China
3FAFU and UIUC-SIB Joint Center for Genomics and Biotechnology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
4Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61822, USA

Horticulture Research 7,
Article number: 20010 (2020)
doi: 10.1038/hortres.2020.10
Views: 435

Received: 09 Sep 2019
Revised: 30 Nov 2019
Accepted: 04 Dec 2019
Published online: 07 Jan 2020

Abstract

The expanded outer seed coat and the rigid inner seed coat of pomegranate seeds, both affect the sensory qualities of the fruit and its acceptability to consumers. Pomegranate seeds are also an appealing model for the study of seed coat differentiation and development. We conducted nontarget metabolic profiling to detect metabolites that contribute to the morphological differentiation of the seed coats along with transcriptomic profiling to unravel the genetic mechanisms underlying this process. Comparisons of metabolites in the lignin biosynthetic pathway accumulating in seed coat layers at different developmental stages revealed that monolignols, including coniferyl alcohol and sinapyl alcohol, greatly accumulated in inner seed coats and monolignol glucosides greatly accumulated in outer seed coats. Strong expression of genes involved in monolignol biosynthesis and transport might explain the spatial patterns of biosynthesis and accumulation of these metabolites. Hemicellulose constituents and flavonoids in particular accumulated in the inner seed coat, and candidate genes that might be involved in their accumulation were also identified. Genes encoding transcription factors regulating monolignol, cellulose, and hemicellulose metabolism were chosen by coexpression analysis. These results provide insights into metabolic factors influencing seed coat differentiation and a reference for studying seed coat developmental biology and pomegranate genetic improvement.