Grain Quality and Nutrition Center, Plant Breeding Division, International Rice Research Institute, Los Baños, Laguna, 4030, Philippines.
ARC Industrial Transformation Training Centre for Functional Grains (FGC), Graham Centre for Agricultural Innovation, Charles Sturt University, Wagga, Wagga NSW, 2650, Australia.
Sci Rep. 2017 Jul 19;7(1):5854. doi: 10.1038/s41598-017-06026-0.
Rice lines with slower starch digestibility provide opportunities in mitigating the global rise in type II diabetes and related non-communicable diseases. However, screening for low glycemic index (GI) in rice breeding programs is not possible due to time and cost constraints. This study evaluated the feasibility of using in vitro cooked grain amylolysis, starch mobilization patterns during seed germination, and variation in starch structure and composition in the mature seed to differentiate patterns of starch digestibility. Mobilization patterns of total starch, resistant starch, amylose and amylopectin chains, and free sugars during seed germination revealed that the process is analogous to digestion in the human gastrointestinal tract. The combination of these biochemical markers can be used as an alternative measure to predict GI. Additionally, transcriptome analysis of stored mRNA transcripts in high and low GI lines detected differences in starch metabolism and confirmed the importance of seed storage pathways in influencing digestibility. Pathway analyses supported by metabolomics data revealed that resistant starch, cell wall non-starch polysaccharides and flavonoids potentially contribute to slower digestibility. These new insights can guide precision breeding programs to produce low GI rice with acceptable cooking quality to help mitigate the burden of diet-associated lifestyle diseases.
富含慢消化淀粉的水稻品种为降低全球 2 型糖尿病和相关非传染性疾病的发病率提供了契机。然而，由于时间和成本的限制，在水稻育种计划中筛选低血糖指数（GI）是不可能的。本研究评估了使用体外煮谷淀粉水解、种子萌发过程中淀粉动员模式以及成熟种子中淀粉结构和组成的变异性来区分淀粉消化率模式的可行性。种子萌发过程中总淀粉、抗性淀粉、直链淀粉和支链淀粉链以及游离糖的动员模式表明，这一过程类似于人体胃肠道的消化。这些生化标志物的组合可以作为预测 GI 的替代指标。此外，高和低 GI 品系中储存的 mRNA 转录本的转录组分析检测到淀粉代谢的差异，并证实了种子储存途径在影响消化率方面的重要性。代谢组学数据支持的途径分析表明，抗性淀粉、细胞壁非淀粉多糖和类黄酮可能有助于减缓消化。这些新的见解可以指导精准育种计划生产具有可接受烹饪品质的低 GI 大米，以帮助减轻与饮食相关的生活方式疾病的负担。
