Low-temperature stress at the booting stage reduces high-quality aromatic rice quality by improving the albumin and amylose contents.

Abstract

High-quality aromatic rice (HAR) is most sensitive to low-temperature stress at the booting stage (LTB), and LTB leads to quality reduction. The key enzymes involved in nitrogen and carbon metabolism significantly affect the synthesis of proteins and starch, thereby influencing the nutritional and taste quality of rice. However, to date, no studies have focused on the after-effects of low-temperature at booting on the quality formation of HAR. In our study, LTB significantly (p < 0.05) increased the activity of ornithine-δ-aminotransferase and proline content in the leaves, leading to increased albumin and protein contents in the grains. Furthermore, LTB significantly (p < 0.05) decreased the activities of adenosine diphosphate glucose pyrophosphorylase and starch branching enzymes, resulting in a reduction of starch and amylopectin contents and an increase in amylose content, ultimately degrading the nutritional quality. The increase in albumin and amylose contents, coupled with the decrease in starch and amylopectin contents, led to a reduction in the peak viscosity and breakdown of starch, as well as an increase in setback, further compromising the taste quality. Additionally, the rise in albumin and amylose contents diminished the aroma, mouthfeel, gloss, and overall taste value of the rice, thus degrading the taste quality. The impact of LTB on the amylose and protein contents in rice Suijing4, a cold-sensitive variety, was greater than that observed in Kendao08-169, a cold-tolerant variety, with the opposite effect noted for albumin. Therefore, the LTB can increase the contents of albumin and amylose, which can worsen the quality of HAR.