Genetic dissection of vitamin E content in rice (Oryza sativa) grains using recombinant inbred lines derived from a cross between 'Zhenshan97B' and 'Nanyangzhan'

Abstract

Vitamin E (VE) is an important nutritional trait in rice grains. In order to dissect the genetic basis underlying VE content, a recombinant inbred lines population derived from 'Zhenshan 97B' and 'Nanyangzhan' was used for quantitative trait locus (QTL) analysis. Totally, 29 QTLs for six VE traits were identified in 2 consecutive years. Among those, five QTLs repeatedly detected in two years formed a cluster on chromosome 2, which was responsible for all five VE isomers. OsγTMT, the gene encoding γ‐tocopherol methyltransferase in rice, was located to the same region and treated as the candidate gene. Sequence analysis of alleles from two parents revealed many polymorphisms, including 19 single nucleotide polymorphisms (SNPs) and two insert/deletions (Indels) in the promoter region, two nonsynonymous SNPs in exons, and 25 SNPs and an Indel in introns. Besides, a QTL for δ‐tocotrienol and two QTLs for α‐tocopherol were repeatedly detected on chromosome 5 and 8, respectively, all three regions carrying no homologous genes involved in VE biosynthesis. These results could be useful in development of rice lines displaying desirable VE content.

A Summary of Two Decades of QTL and Candidate Genes That Control Seed Tocopherol Contents in Maize (Zea mays L.)

“…Zhan et al (2019) grew three RIL populations (n = 170-188 lines) from the crosses of Zong3 by Yu8701 (ZXY), K22XCI7, and B73 by BY804 (BXB) in two environments in China and genotyped them with 50 k SNPs. They used CIM of WinQTLCart2.5 for QTL analysis and identified one major QTL that controls seed γ-tocopherol and total tocopherol (qVE5) on chromosome 5 [48]. The major QTL qVE5 was also identified in a previous study [44] and confirmed here in these three RIL populations [49].…”

“…Wang et al (2018) identified 41 QTL and 151 SNPs associated with seed tocopherol-related traits and many candidate genes within these QTL regions, including GRMZM2G436226 that encodes a Zinc finger CCCH domain-containing protein on chromosome 1, GRMZM2G055752 that encodes a DNA topoisomerase and GRMZM2G079236 that encodes a Acyl-CoA synthetase long-chain family member on chromosome 2, GRMZM2G170013 that encodes a chlorophyll b reductase NYC1 on chromosome 3, GRMZM5G892742 that encodes a DNAJ-related chaperone protein and GRMZM2G150714 that encodes a putative leucine-rich repeat receptor-like protein kinase family protein on chromosome 4, GRMZM2G035213 that encodes a γ-tocopherol methyltransferase (VTE4) and GRMZM2G024739 that encodes a Cryptochrome-1 (CRY1) on chromosome 5, GRMZM2G127299 that encodes a transcription factor GTE8 and GR-MZM2G146190 that encodes a peptidyl-prolyl cis-trans isomerase (CYP59) on chromosome 6, GRMZM2G003022 that encodes a COPII vesicle coat on chromosome 8, GRMZM5G818232 that encodes a Clavata3/esr-related16 on chromosome 9, GRMZM2G004534 that encodes a pyruvate kinase 2 on chromosome 10, and many other genes (Table S1) [44]. Zhang et al (2019) created transgenic seeds of maize and Arabidopsis thaliana and overexpressed the gene ZmTMT (VTE4) that encodes γ-tocopherol methyltransferase in those seeds and observed a 4-5-fold increase in α-tocopherol content in Arabidopsis and 6.5-fold increase in maize transgenic plants while the (α/γ)-tocopherol ratio increased by 15-fold and 17-fold, respectively, which proves that increasing tocopherol content in corn is feasible [48]. Zhan et al (2019) grew three RIL populations (n = 170-188 lines) from the crosses of Zong3 by Yu8701 (ZXY), K22XCI7, and B73 by BY804 (BXB) in two environments in China and genotyped them with 50 k SNPs.…”

Exploring the genic resources underlying metabolites through mGWAS and mQTL in wheat: From large-scale gene identification and pathway elucidation to crop improvement

“…Indeed, for instance, wheat germ oils contain the highest concentration of vitamin E of all species tested ( Trela and Szymańska, 2019 ). Although substantial efforts have been made in elucidating the metabolic pathway of vitamin metabolism in other crops ( Zhou et al., 2012 ; Quadrana et al., 2014 ; Liu et al., 2017 ; Wang et al., 2018 ; Schuy et al., 2019 ; Zhang et al., 2019 ), less has been achieved in wheat ( Li et al., 2018b ; Watkins et al., 2019 ). In view of this, key candidate genes could be swiftly selected and validated through multi-omics approaches including metabolomics, providing molecular resources for breeding wheat to be a more nutritional food.…”

Distribution of γ-oryzanol in the outer layers of brown rice and its variation among cultivars

“…In addition, there are apparent variations in the contents of these compounds among rice cultivars (Bergman & Xu, 2003;Heineman et al, 2008;Huang & Ng, 2011;Kato et al, 2017;Ng et al, 2013). Several quantitative trait loci have been identified for the contents of gOZ (Kato et al, 2017;Nakano et al, 2018) and vitamin E derivatives (Zhang et al, 2019).…”