Department of Botany, Savitribai Phule Pune University, Pune, 411007, Maharashtra, India.
The University Polytechnic, Aligarh Muslim University, Aligarh, 202002, India.
Sci Rep. 2022 Mar 10;12(1):3911. doi: 10.1038/s41598-022-07844-7.
Aromatic rice (Oryza sativa) fetches a premium price due to the pleasant aroma. The major aroma compound 2-acetyl-1-pyrroline (2AP) has been found to be enhanced under stress. This condition can be considered to study the genes, precursors, enzymes, and metabolites involved in elevated levels of 2AP biosynthesis. In the present study, 100 mM salt treatment was given to two aromatic rice cultivars Ambemohar-157 (A-157) and Basmati-370 (B-370) at the vegetative stage (VS). After salt treatment, in the leaves, 2AP contents were elevated by 2.2 and 1.8 fold in A-157 and B-370, respectively. Under these elevated 2AP conditions, the precursor amino acids (glutamate, putrescine, ornithine, and proline), their related genes, enzymes, and metabolites (methylglyoxal and γ-aminobutyric acid (GABA) related to 2AP biosynthesis were analyzed. In addition, agronomic characters were also studied. It was observed that the proline content was enhanced in both the cultivars by 29% (A-157) and 40% (B-370) as compared to control. The Δ-pyrroline-5-carboxylate synthetase (P5CS) enzyme activity was increased in salt-treated plants leaf tissue by 31% (A-157) and 40% (B-370) compared to control. The P5CS gene expression was enhanced by A-157 (1.8 fold) and B-370 (2.2 fold) compared to control, putrescine content in A-157 and B-370 decreased by 2.5 and 2.7 fold respectively as compared to control. The ornithine decarboxylase (ODC) activity was enhanced in A-157 (12%) and B-370 (35%) over control. Further, ODC gene expression was enhanced in both the cultivars A-157 (1.5 fold) and B-370 (1.3 fold). The diamino oxidase (DAO) enzyme activity was increased by 28% (A-157) and 35% (B-370) respectively over control. The GABA content marginally increased over control in both the cultivars namely, A-157 (1.9%) and B-370 (9.5%). The methylglyoxal levels were enhanced by 1.4 fold in A-157 and 1.6 fold in B-370. Interestingly, the enhancement in 2AP in the vegetative stage also helped to accumulate it in mature grains (twofold in A-157 and 1.5 fold in B-370) without test weight penalty. The study indicated that the ornithine and proline together along with methylglyoxal contribute towards the enhancement of 2AP under salt stress.
芳香稻（Oryza sativa）因其宜人的香气而价格不菲。已发现主要香气化合物 2-乙酰-1-吡咯啉（2AP）在胁迫下会增强。这种情况可用于研究参与 2AP 生物合成水平升高的基因、前体、酶和代谢物。在本研究中，在营养生长阶段（VS），用 100mM 盐处理两种芳香稻品种 Ambemohar-157（A-157）和 Basmati-370（B-370）。盐处理后，A-157 和 B-370 的叶片中 2AP 含量分别升高了 2.2 倍和 1.8 倍。在这些升高的 2AP 条件下，分析了前体氨基酸（谷氨酸、腐胺、鸟氨酸和脯氨酸）、它们的相关基因、酶和代谢物（与 2AP 生物合成相关的甲基乙二醛和γ-氨基丁酸（GABA））。此外，还研究了农艺性状。观察到与对照相比，两种品种的脯氨酸含量分别增加了 29%（A-157）和 40%（B-370）。与对照相比，盐处理植物叶片组织中的 Δ-吡咯啉-5-羧酸合成酶（P5CS）酶活性分别增加了 31%（A-157）和 40%（B-370）。与对照相比，A-157（1.8 倍）和 B-370（2.2 倍）的 P5CS 基因表达增强，A-157 和 B-370 的腐胺含量分别降低了 2.5 倍和 2.7 倍。鸟氨酸脱羧酶（ODC）活性在 A-157（12%）和 B-370（35%）中均高于对照。此外，A-157（1.5 倍）和 B-370（1.3 倍）两种品种的 ODC 基因表达均增强。二胺氧化酶（DAO）酶活性分别比对照增加了 28%（A-157）和 35%（B-370）。与对照相比，两种品种的 GABA 含量分别略有增加，即 A-157（1.9%）和 B-370（9.5%）。甲基乙二醛水平在 A-157 中增加了 1.4 倍，在 B-370 中增加了 1.6 倍。有趣的是，营养生长阶段 2AP 的增强也有助于在成熟谷物中积累 2AP（A-157 增加两倍，B-370 增加 1.5 倍），而不会对重量造成惩罚。研究表明，在盐胁迫下，鸟氨酸和脯氨酸与甲基乙二醛一起共同促进 2AP 的增强。
