| Affiliation: | 1. Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Eco-Circular Agriculture, Guangdong Engineering Research Centre for Modern Eco-Agriculture, College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642 People’s Republic of China;2. Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Eco-Circular Agriculture, Guangdong Engineering Research Centre for Modern Eco-Agriculture, College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642 People’s Republic of China Institutes of Physical Science and Information Technology, Anhui University, Hefei, Anhui, 230601 People’s Republic of China;3. Faculty of Agriculture, Tottori University, Koyama, Tottori, 680-8553 Japan;4. School of Integrative Plant Sciences, Cornell University, Ithaca, NY, 14853 USA;5. China Tobacco Guangxi Industrial Co. Ltd, Nanning, Guangxi, 530001 People’s Republic of China;6. China Tobacco Guangdong Industrial Co. Ltd, Guangzhou, 510610 People’s Republic of China;7. Guangdong Provincial Tobacco Shaoguan Co. Ltd, Shaoguan, Guangdong, 512000 People’s Republic of China;8. Institutes of Physical Science and Information Technology, Anhui University, Hefei, Anhui, 230601 People’s Republic of China;9. Boyce Thompson Institute for Plant Research, Ithaca, NY, 14853 USA |
| Abstract: | Naringenin, the biochemical precursor for predominant flavonoids in grasses, provides protection against UV damage, pathogen infection and insect feeding. To identify previously unknown loci influencing naringenin accumulation in rice (Oryza sativa), recombinant inbred lines derived from the Nipponbare and IR64 cultivars were used to map a quantitative trait locus (QTL) for naringenin abundance to a region of 50 genes on rice chromosome 7. Examination of candidate genes in the QTL confidence interval identified four predicted uridine diphosphate-dependent glucosyltransferases (Os07g31960, Os07g32010, Os07g32020 and Os07g32060). In vitro assays demonstrated that one of these genes, Os07g32020 (UGT707A3), encodes a glucosyltransferase that converts naringenin and uridine diphosphate-glucose to naringenin-7-O-β-d -glucoside. The function of Os07g32020 was verified with CRISPR/Cas9 mutant lines, which accumulated more naringenin and less naringenin-7-O-β-d -glucoside and apigenin-7-O-β-d -glucoside than wild-type Nipponbare. Expression of Os12g13800, which encodes a naringenin 7-O-methyltransferase that produces sakuranetin, was elevated in the mutant lines after treatment with methyl jasmonate and insect pests, Spodoptera litura (cotton leafworm), Oxya hyla intricata (rice grasshopper) and Nilaparvata lugens (brown planthopper), leading to a higher accumulation of sakuranetin. Feeding damage from O. hyla intricata and N. lugens was reduced on the Os07g32020 mutant lines relative to Nipponbare. Modification of the Os07g32020 gene could be used to increase the production of naringenin and sakuranetin rice flavonoids in a more targeted manner. These findings may open up new opportunities for selective breeding of this important rice metabolic trait. |
