Tansawat Rossarin, Jindawatt Supawat, Ekkaphan Paweena, Ruengphayak Siriphat, Vanavichit Apichart, Suttipanta Nitima, Vimolmangkang Sornkanok, De-Eknamkul Wanchai
Department of Food and Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok, Thailand.
Scientific and Technological Research Equipment Center, Chulalongkorn University, Bangkok, Thailand.
Front Plant Sci. 2023 Feb 28;14:973217. doi: 10.3389/fpls.2023.973217. eCollection 2023.
In addition to white jasmine rice, Thailand has many native-colored rice varieties with numerous health benefits and the potential to become a global economic crop. However, the chemical characteristics of aromatic substances in native-colored rice are still mostly unknown. This study aimed to identify the key volatile aroma compounds and the biosynthetic pathways possibly involved in their formation in Thai native-colored rice varieties, and thus leading to the search for potential genetic markers for breeding colored rice with better aromatic properties. Twenty-three rice varieties in four categories: aromatic white, aromatic black, non-aromatic black, and non-aromatic red, were investigated (n=10 per variety). Seed husks were removed before the analysis of rice volatile aromas by static headspace gas chromatography-mass spectrometry. Untargeted metabolomics approach was used to discover the key volatile compounds in colored rice. Forty-eight compounds were detected. Thirty-eight of the 48 compounds significantly differed among groups at p<0.05, 28 of which at p<0.0001, with the non-aromatic black and red rice containing much lower content of most volatile constituents than the aromatic black and white rice. Focusing on the aromatic black rice, the samples appeared to contain high level of both compound groups of aldehydes (3-methylbutanal, 2-methylbutanal, 2-methylpropanal, pentanal, hexanal) and alcohols (butane-2,3-diol, pentan-1-ol, hexan-1-ol). Biosynthetically, these distinctive black-rice volatile compounds were proposed to be formed from the metabolic degradation of branched-chain amino acids (L-leucine, L-isoleucine and L-valine) and polyunsaturated fatty acids (linoleic acid and α-linolenic acid), involving the branched-chain aminotransferases and keto-acid decarboxylases and the 9-lipoxygonases and 13-lipoxygeases, respectively. The proposed degradative pathways of amino acids and fatty acids were well agreed with the profiles key volatile compounds detected in the Thai native-colored rice varieties.
除了白茉莉香米外，泰国还有许多本土有色稻米品种，它们具有诸多健康益处，并有潜力成为全球经济作物。然而，本土有色稻米中芳香物质的化学特性大多仍不为人知。本研究旨在鉴定泰国本土有色稻米品种中关键的挥发性香气化合物及其可能参与形成的生物合成途径，从而寻找潜在的遗传标记，用于培育具有更好香气特性的有色稻米。研究了四类共23个水稻品种：香白米、香黑米、非香黑米和非香红米（每个品种n = 10）。在通过静态顶空气相色谱 - 质谱联用仪分析水稻挥发性香气之前，先去除稻壳。采用非靶向代谢组学方法来发现有色稻米中的关键挥发性化合物。共检测到48种化合物。48种化合物中有三十八种在组间存在显著差异（p < 0.05），其中二十八种在p < 0.0001水平上存在差异，非香黑米和红米中大多数挥发性成分的含量远低于香黑米和香白米。聚焦于香黑米，样品似乎含有高水平的醛类（3 - 甲基丁醛、2 - 甲基丁醛、2 - 甲基丙醛、戊醛、己醛）和醇类（2,3 - 丁二醇、戊醇、己醇）这两类化合物。在生物合成方面，这些独特的黑米挥发性化合物被认为是由支链氨基酸（L - 亮氨酸、L - 异亮氨酸和L - 缬氨酸）和多不饱和脂肪酸（亚油酸和α - 亚麻酸）的代谢降解形成的，分别涉及支链氨基转移酶和酮酸脱羧酶以及9 - 脂氧合酶和13 - 脂氧合酶。所提出的氨基酸和脂肪酸降解途径与在泰国本土有色稻米品种中检测到的关键挥发性化合物谱图高度吻合。
