Sekine Daisuke, Murata Kazumasa, Kimura Toshiyuki, Nakagawa Kiyotaka, Miyazawa Teruo
Agricultural Experiment Station, Toyama Agricultural Research Center , Toyama, Toyama 939-8153, Japan.
Division of Life Sciences, Graduate School of Natural Science and Technology, Kanazawa University , Kanazawa, Ishikawa 920-1192, Japan.
J Agric Food Chem. 2016 Dec 14;64(49):9368-9373. doi: 10.1021/acs.jafc.6b04801. Epub 2016 Dec 6.
The γ-isoforms of tocopherols (Tc) and tocotrienols (T3) possess high biological activities in comparison to the α-isoforms. The concentrations of Tc and T3 isoforms in rice (Oriza sativa) was cultivar-dependent. Using chromosome segment substitution lines (CSSLs) and near isogenic lines (NILs) of indica cultivar "Kasalath" in a japonica cultivar "Koshihikari" genetic background, the Kasalath genomic segment on chromosome 2 was determined to be responsible for the high γ-isoform concentration: γ-tocopherol methyltransferase (γ-TMT) was identified as a candidate gene. An amino acid substitution in the coding region and several nucleotide polymorphisms, including an insertion of 10 base pairs in the promoter region, were identified. Gene expression analysis revealed that low expression levels of the γ-TMT gene in Kasalath were not associated with the γ-isoform concentration. Genetic variations in the coding region of the γ-TMT gene may play a major role in determining the γ-isoform concentration. This information could be used to breed rice with a high γ-isoform content.
与α-异构体相比，生育酚（Tc）和生育三烯酚（T3）的γ-异构体具有较高的生物活性。水稻（Oriza sativa）中Tc和T3异构体的浓度因品种而异。利用粳稻品种“越光”遗传背景下的籼稻品种“Kasalath”的染色体片段代换系（CSSL）和近等基因系（NIL），确定第2号染色体上的Kasalath基因组片段与γ-异构体的高浓度有关：γ-生育酚甲基转移酶（γ-TMT）被鉴定为候选基因。在编码区发现了一个氨基酸替换以及几个核苷酸多态性，包括启动子区域插入了10个碱基对。基因表达分析表明，Kasalath中γ-TMT基因的低表达水平与γ-异构体浓度无关。γ-TMT基因编码区的遗传变异可能在决定γ-异构体浓度方面起主要作用。这些信息可用于培育高γ-异构体含量的水稻。
