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.
Plant J. 2021 Jun;106(5):1401-1413. doi: 10.1111/tpj.15244. Epub 2021 Apr 17.
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.
柚皮素是草类中主要类黄酮的生化前体，可提供对紫外线损伤、病原体感染和昆虫取食的保护。为了鉴定以前未知的影响水稻（Oryza sativa）柚皮素积累的基因座，利用源自 Nipponbare 和 IR64 品种的重组自交系，将一个柚皮素丰度的数量性状基因座（QTL）定位到水稻 7 号染色体上 50 个基因的区域。在 QTL 置信区间内对候选基因的研究鉴定了四个预测的尿苷二磷酸依赖性葡萄糖基转移酶（Os07g31960、Os07g32010、Os07g32020 和 Os07g32060）。体外测定表明，其中一个基因 Os07g32020（UGT707A3）编码一种葡萄糖基转移酶，可将柚皮素和尿苷二磷酸-葡萄糖转化为柚皮素-7-O-β-D-葡萄糖苷。利用 CRISPR/Cas9 突变系验证了 Os07g32020 的功能，该突变系比野生型 Nipponbare 积累了更多的柚皮素、更少的柚皮素-7-O-β-D-葡萄糖苷和芹菜素-7-O-β-D-葡萄糖苷。茉莉酸甲酯和鳞翅目害虫（斜纹夜蛾、稻蝗和褐飞虱）处理后，Os12g13800 基因（编码产生樱花素的柚皮素 7-O-甲基转移酶）在突变系中的表达升高，导致樱花素积累增加。与 Nipponbare 相比，Os07g32020 突变系上 O. hyla intricata 和 N. lugens 的取食损伤减少。对 Os07g32020 基因的修饰可以更有针对性地增加水稻类黄酮中柚皮素和樱花素的产量。这些发现可能为这一重要的水稻代谢性状的选择性育种开辟新的机会。
