Abstract：
BACKGROUND: High-temperature (HT) stress significantly affects the quality of rice (Oryza sativa L.), although the underlying the mechanism remains unknown. Therefore, in the present study, we assessed protein components, amino acids, mineral element levels, starch biosynthesis enzyme activity and gene expression of two heat-sensitive and two heat-tolerant genotypes under HT treatment during early (from 1 to 10 days, T1) and mid-filling (from 11 to 20 days, T2) after anthesis.
RESULTS: Except for one cultivar, most rice varieties exhibited increased levels of amylose, chalky degree and protein content, along with elevated cracked grains and pasting temperatures and, consequently, suppressed amino acid levels under HT stress. HT treatment also increased protein components, macro- (Mg, K, P and S) and microelements (Cu, Zn, and Mo) in the rice flour. Both HT treatments reduced the activity of ADP-glucose pyrophosphate, ground-bound starch synthase, as well as the relative ratio of amylose to total starch, at the same time increasing starch branch enzyme activity. The expression levels of OsAGPL2, OsSSS1 and OsSBE1 in all varieties exhibited the same trends as enzyme activity under HT treatment.
CONCLUSIONS: High temperatures negatively affected rice quality during grain filling, which is related to heat tolerance and grain shape. Altered enzymatic activity is crucial to compensate for the lowered enzyme quality under heat stress. © 2024 Society of Chemical Industry.
RESULTS: Except for one cultivar, most rice varieties exhibited increased levels of amylose, chalky degree and protein content, along with elevated cracked grains and pasting temperatures and, consequently, suppressed amino acid levels under HT stress. HT treatment also increased protein components, macro- (Mg, K, P and S) and microelements (Cu, Zn, and Mo) in the rice flour. Both HT treatments reduced the activity of ADP-glucose pyrophosphate, ground-bound starch synthase, as well as the relative ratio of amylose to total starch, at the same time increasing starch branch enzyme activity. The expression levels of OsAGPL2, OsSSS1 and OsSBE1 in all varieties exhibited the same trends as enzyme activity under HT treatment.
CONCLUSIONS: High temperatures negatively affected rice quality during grain filling, which is related to heat tolerance and grain shape. Altered enzymatic activity is crucial to compensate for the lowered enzyme quality under heat stress. © 2024 Society of Chemical Industry.
摘要：
背景：高温（HT）胁迫显着影响水稻（OryzasativaL.）的品质，尽管潜在的机制仍然未知。因此,在本研究中，我们评估了蛋白质成分，氨基酸,矿质元素含量,在早期（从1到10天，T1)和中期填充(从11到20天，T2)花后。
结果：除了一个品种，大多数水稻品种的直链淀粉含量增加，白垩度和蛋白质含量，随着裂纹颗粒和糊化温度的升高，因此,在HT胁迫下抑制氨基酸水平。HT处理也增加了蛋白质成分，宏-(Mg，K,P和S）和微量元素（Cu，Zn,和Mo）在米粉中。两种HT处理均降低了ADP-葡萄糖焦磷酸盐的活性，研磨结合淀粉合成酶，以及直链淀粉与总淀粉的相对比例，同时增加淀粉分支酶活性。OsAGPL2、OsSSS1和OsSBE1在所有品种中的表达水平均表现出与HT处理下的酶活性相同的趋势。
结论：高温在籽粒灌浆过程中对稻米品质产生负面影响，这与耐热性和颗粒形状有关。改变酶活性对于补偿热应激下降低的酶质量至关重要。©2024化学工业学会。
结果：除了一个品种，大多数水稻品种的直链淀粉含量增加，白垩度和蛋白质含量，随着裂纹颗粒和糊化温度的升高，因此,在HT胁迫下抑制氨基酸水平。HT处理也增加了蛋白质成分，宏-(Mg，K,P和S）和微量元素（Cu，Zn,和Mo）在米粉中。两种HT处理均降低了ADP-葡萄糖焦磷酸盐的活性，研磨结合淀粉合成酶，以及直链淀粉与总淀粉的相对比例，同时增加淀粉分支酶活性。OsAGPL2、OsSSS1和OsSBE1在所有品种中的表达水平均表现出与HT处理下的酶活性相同的趋势。
结论：高温在籽粒灌浆过程中对稻米品质产生负面影响，这与耐热性和颗粒形状有关。改变酶活性对于补偿热应激下降低的酶质量至关重要。©2024化学工业学会。
