Flavonoid Metabolic Profiles and Gene Mapping of Rice (Oryza sativa L.) Purple Gradient Grain Hulls

Abstract

Rice (Oryza sativa L.) grain hull color is an easily observable trait and regarded as a crucial morphological marker in rice breeding. Here, a purple gradient grain hull mutant (pg) was found from natural mutations of a straw-white grain hull rice variety IARI 6184B (Orzya sativa L. subsp. indica). The color of the mutant grain hulls changed from straw-white to pink, then purple, and finally brownish-yellow. Ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) identified 217 flavonoids, including 18 anthocyanins, among which cyanidin O-syringic acid had the highest concentration in pink (66.2 × 106) and purple (68.0 × 106) grain hulls. The relative contents of hesperetin O-malonyl-hexoside, apigenin derivatives, genistein derivatives, and kaempferol 3-O derivatives were consistently downregulated during pg grain hull development. Conversely, 12 anthocyanins were upregulated in colored hulls, and cyanidin 3-O-malonylhexoside was abundant only in pink and purple grain hulls. Moreover, the candidate gene was mapped into a 1.38 Mb region on chromosome 4 through bulked segregant analysis based on deep sequencing (BSA-seq) and gene mapping approaches. These results increased our understanding of anthocyanin biosynthesis in rice grains, helping rice breeders to select new rice varieties with desirable grain traits.

Characterization of chromosomal segment substitution lines developed in the genetic background of rice variety K 343

“…Similarly, a CSSL population with average donor introgression of 2% was developed [18] and it was observed that substituted segments of donor parent (Yangdao 6) constituted on an average of 5% of the whole rice genome [19]. Three sets of CSSLs with greater coverage of substituted segments were developed [8] using various donor-recipient combinations. In another study, 93.37% of the whole donor genome was covered [20].…”

“…The successful application of novel QTL in rice improvement via CSSLs is well documented [5,6,7]. In addition, certain distinct morphological characteristics of wild rice that are derived from CSSLs were utilized as useful phenotypic markers in rice breeding programs [8]. Thus, this investigation aimed to develop two sets of CSSLs in the genetic background of the rice variety K343, followed by their characterization in terms of the genomic contribution of donor lines DHMAS and RML 22.…”

Metabolomics and transcriptomics analyses provide new insights into the nutritional quality during the endosperm development of different ploidy rice

“…In tetraploid rice, the protein and amino acid levels rise, but the amylose concentration frequently declines ( Wang et al., 2022c ). Functional proteins, oils, vitamins, flavonoids, trace minerals, necessary amino acids, and functional and essential proteins are unique nutritional components found in rice ( Nam et al., 2018 ; Yang et al., 2019 ; Sabooni and Gharaghani, 2022 ; Zhang et al., 2022 ). Strong antioxidant properties of flavonoids were demonstrated by their ability to directly scavenge free radicals, inhibit the production of free radicals by the enzyme oxidase, chelate metal ions produced by free radicals, and promote the regeneration of antioxidant enzymes and small-molecular antioxidant factors ( Bors and Michel, 2002 ; Borges-Bubols et al., 2013 ).…”

Characteristics of antioxidant capacity and metabolomics analysis of flavonoids in the bran layer of green glutinous rice (Oryza sativa L. var. Glutinosa Matsum)

“…Metabolomics is a powerful tool for detecting metabolites within metabolic pathways, revealing distinct differences in flavonoid metabolite synthesis among colored rice varieties 42 .Using the UPLC–MS/MS platform, LvH bran was found to typically have elevated levels of apigenin derivatives, catechin gallate, diosmetin derivatives, epicatechin gallate, and tricin-4′- O -(guaiacylglycerol)ether-7- O -glucoside compared to HeiH, HongH, and GJG. In addition, LvH bran had significantly higher levels of 23 flavonoids that were present at low levels in HeiH bran.…”