Transcriptional analysis for the difference in carotenoids accumulation in flesh and peel of white-fleshed loquat fruit.

Shicheng Zou,Shunquan Lin,Xianghui Yang,Muhammad Qasim Shahid,Yehua He,Chongbin Zhao,Man Wang,Yunlu Bai,Zhenhai Han

doi:10.1371/journal.pone.0233631

Shicheng Zou, Shunquan Lin + Show 7 more

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https://doi.org/10.1371/journal.pone.0233631

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Journal: PloS one	Publication Date: Jun 26, 2020
Citations: 6	License type: CC BY 4.0

Affiliation: South China Agricultural University

Abstract

Loquat (Eriobotrya japonica Lindl.) is divided into yellow- and white-fleshed based on the difference in fruit color, and the variations in carotenoids accumulation are considered as the main reasons for this difference. Using RNA-seq technology, a transcriptome analysis was carried out on the flesh and peel of ‘Baiyu’ fruit during four different fruit development stages. A total of 172.53 Gb clean reads with an average of 6.33 Gb reads were detected for each library, and the percentage of Q30 was higher than 90.84%. We identified 16 carotenogenic and 13 plastid-lipid-associated protein (PAP) genes through RNA-seq. Of these, five carotenogenic and four PAP related genes exhibited remarkable differences in the expression patterns. Carotenoids biosynthetic genes, including DXS, PSY1 and VDE displayed higher expression levels in peel than that in the flesh. However, carotenoids decomposition gene, such as NCDE1, exhibited higher expression in flesh than that in the peel. Notably, all differentially expressed PAP genes showed higher expression levels in peel than flesh. We inferred that the differential accumulation of carotenoids in flesh and peel of 'Baiyu' is caused by the up- or down-regulation of the carotenogenic and PAP related genes. The functional analysis of these important genes will provide valuable information about underlying molecular mechanism of carotenoids accumulation in loquat.

Highlights

Fruit color formation depends on the pigment accumulation, and the types and contents of pigments determine the shades and color of fruit
From RNA-seq data, we identified 16 carotenogenic genes and 13 plastid-lipid-associated protein (PAP) genes, among them, five carotenogenic genes, including PSY1, PSY2B, DXS, VDE, and NCED1 were found to be differentially expressed between flesh and peel, and four PAP genes, including PAP6, PAP8, PAP11, and PAP12 displayed differential expression patterns between flesh and peel (Fig 5)
The expression level of PSY1 has the same profile in flesh and peel, but its expression level in peel was much higher than that in flesh

Summary

Introduction

Fruit color formation depends on the pigment accumulation, and the types and contents of pigments determine the shades and color of fruit. The carotenoids are the major pigment in many fruits, which cause a difference in fruit color, and a synthetic precursor of photosynthetic auxiliary pigment, ABA and some aromatic substances. Carotenoids biosynthesis and accumulation have attracted great attention because of the physiological role and human health-care functions [1, 2]. After the identification of carotenoids biosynthesis pathway in plants, the expression and cloning of carotenogenic genes in different plants have become a research hotspot [3,4,5,6]. Recent studies have shown that the carotenoids.

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