Generation of aroma in three-line hybrid rice through CRISPR/Cas9 editing of BETAINE ALDEHYDE DEHYDROGENASE2 (OsBADH2).

Aroma or fragrance in rice is a genetically controlled trait; Its high appreciation by consumers increases the rice market price. Previous studies have revealed that the rice aroma is controlled by a specific gene called BETAINE ALDEHYDE DEHYDROGENASE (OsBADH2), and mutation of this gene leads to the accumulation of an aromatic substance 2-acetyl-1-pyrroline (2-AP). The use of genetic engineering to produce aroma in commercial and cultivated hybrids is a contemporary need for molecular breeding. The current study reports the generation of aroma in the three-line hybrid restorer line Shu-Hui-313 (SH313). We created knock-out (KO) lines of OsBADH2 through the CRISPR/Cas9. The analysis of KO lines revealed a significantly increased content of 2AP in the grains compared with the control. However, other phenotypic traits (plant height, seed setting rate, and 1000-grain weight) were significantly decreased. These KO lines were crossed with a non-aromatic three-line hybrid rice male sterile line (Rong-7-A) to produce Rong-7-You-626 (R7Y626), R7Y627 and R7Y628. The measurement of 2-AP revealed significantly increased contents in these cross combinations. We compared the content of 2-AP in tissues at the booting stage. Data revealed that young spike stalk base contained the highest content of 2-AP and can be used for identification (by simple chewing) of aromatic lines under field conditions. In conclusion, our dataset offers a genetic source and illustrates the generation of aroma in non-aromatic hybrids, and outlines a straightforward identification under field conditions.

Investigation of flavonoid components and their associated antioxidant capacity in different pigmented rice varieties.

Black and red rice are flavonoid-rich and nutritious. However, comprehensive information of flavonoid components in different pigmented rice varieties remain unclear. Here, we analyze the differences in flavonoid components in black, red, and white rice by ultra-high-performance liquid chromatography (UPLC) and metabolome analysis. Cyanidin-3-glucoside (Cy-3-G), peonidin-3-glucoside (Pe-3-G), quercetin, dihydromyricetin, naringin, and taxifolin contents were significantly high in black rice. By contrast, catechin and epicatechin contents were substantial in red rice. Cy-3-G was the main anthocyanin and its content was more than four times that of Pe-3-G in black rice varieties. Trifolin hardly showed specificity and exhibited a high content in all rice varieties. The antioxidant capacity of the red and black rice varieties was significantly higher than that of white rice. Moreover, in black and red rice, quercetin and catechin respectively exhibited the strongest antioxidant capacity and a good contribution toward the total flavonoid content, and mean time, white rice possessed antioxidant capacity main derived from quercetin and trifolin. Besides, the study also found that there was slightly inconsistent results between UPLC and metabolome, because certain components with trace by metabolome were not detected by UPLC, but their combination could play a complementary role in the exploration of metabolic components to confirm the ingredients.