Department of Crop Science and Technology, College of Agriculture, South China Agricultural University, Guangzhou, PR China; Scientific Observing and Experimental Station of Crop Cultivation in South China, Ministry of Agriculture, Guangzhou, PR China.
Department of Crop Science and Technology, College of Agriculture, South China Agricultural University, Guangzhou, PR China; Scientific Observing and Experimental Station of Crop Cultivation in South China, Ministry of Agriculture, Guangzhou, PR China; Department of Botany, University of Education, Lahore, Faisalabad-Campus, Faisalabad, 38000, Punjab, Pakistan.
Plant Physiol Biochem. 2018 Dec;133:149-157. doi: 10.1016/j.plaphy.2018.10.032. Epub 2018 Oct 29.
Factors affecting rice aroma biosynthesis have been well documented previously, however the molecular mechanism lies behind the regulations in grain 2-acetyl-1-pyrroline (2AP) biosynthesis under alternate wetting and drying (AWD) remained largely unexplored. Present study investigated the effects of three irrigation regimes i.e., conventional irrigation (CI), alternate wetting and moderate drying (WMD), and alternate wetting and severe drying (WSD) on the yield, quality traits, intermediates, enzyme activities and genes involved in 2-acetyl-1-pyrroline biosynthesis in two fragrant rice cultivars viz, Meixiangzhan2 and Xiangyaxiangzhan. Results revealed that the levels of intermediates such as Δ1-pyrroline-5-carboxylate (P5C) and Δ1-pyrroline, and the activity of enzymes such as proline dehydrogenase (PRODH), Δ1-pyrroline-5-carboxylate synthetase (P5CS), diamine oxidase (DAO), and gene expressions of PRODH, P5CS2 and DAO were comparatively higher under AWD than CI in both aromatic rice cultivars. The levels of gamma-aminobutyric acid (GABA), betaine aldehyde dehydrogenase 2 (BADH2) and BADH2 gene were lower that together led to enhanced 2-AP contents in rice grains. Moreover, WMD irrigation improved yield and yield characters, while WSD irrigation reduced yield and quality traits of rice. Overall, up-regulation of P5C and Δ1-pyrroline and down-regulation of GABA under AWD treatments resulted in enhanced 2AP biosynthesis in both rice cultivars. Evaluation and adoption of AWD (within safe limits) at field level could be an alternative option to conventional flooded rice to get better yield and quality.
先前已经有大量文献记载了影响稻米香气生物合成的因素，但在交替湿润和干燥（AWD）条件下谷物 2-乙酰-1-吡咯啉（2AP）生物合成的调控背后的分子机制在很大程度上仍未得到探索。本研究调查了三种灌溉制度，即常规灌溉（CI）、交替湿润和适度干燥（WMD）以及交替湿润和严重干燥（WSD）对两个香稻品种美香占 2 号和香两优香占的产量、品质特性、中间产物、参与 2-乙酰-1-吡咯啉生物合成的酶活性和基因的影响。结果表明，在两种芳香稻品种中，中间产物如Δ1-吡咯啉-5-羧酸（P5C）和Δ1-吡咯啉的水平，以及脯氨酸脱氢酶（PRODH）、Δ1-吡咯啉-5-羧酸合成酶（P5CS）、二胺氧化酶（DAO）等酶的活性，在 AWD 下均高于 CI。γ-氨基丁酸（GABA）、甜菜碱醛脱氢酶 2（BADH2）和 BADH2 基因的水平较低，这共同导致稻米中 2AP 含量增加。此外，WMD 灌溉提高了产量和产量性状，而 WSD 灌溉降低了水稻的产量和品质性状。总的来说，AWD 处理下 P5C 和Δ1-吡咯啉的上调以及 GABA 的下调导致了两个水稻品种中 2AP 生物合成的增强。在田间水平上评估和采用 AWD（在安全范围内）可能是获得更好产量和品质的替代传统淹水水稻的选择。
