Beijing Key Lab of Greening Plants Breeding, Beijing Academy of Forestry and Landscape Architecture, Beijing, China.
Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, China.
BMC Plant Biol. 2023 Jan 20;23(1):46. doi: 10.1186/s12870-023-04057-6.
Petal blotch is a unique ornamental trait in angiosperm families, and blotch in rose petal is rare and has great esthetic value. However, the cause of the formation of petal blotch in rose is still unclear. The influence of key enzyme genes and regulatory genes in the pigment synthesis pathways needs to be explored and clarified.
In this study, the rose cultivar 'Sunset Babylon Eyes' with rose-red to dark red blotch at the base of petal was selected as the experimental material. The HPLC-DAD and UPLC-TQ-MS analyses indicated that only cyanidin 3,5-O-diglucoside (Cy3G5G) contributed to the blotch pigmentation of 'Sunset Babylon Eyes', and the amounts of Cy3G5G varied at different developmental stages. Only flavonols but no flavone were found in blotch and non-blotch parts. As a consequence, kaempferol and its derivatives as well as quercetin and its derivatives may act as background colors during flower developmental stages. Despite of the differences in composition, the total content of carotenoids in blotch and non-blotch parts were similar, and carotenoids may just make the petals show a brighter color. Transcriptomic data, quantitative real-time PCR and promoter sequence analyses indicated that RC7G0058400 (F3'H), RC6G0470600 (DFR) and RC7G0212200 (ANS) may be the key enzyme genes for the early formation and color deepening of blotch at later stages. As for two transcription factor, RC7G0019000 (MYB) and RC1G0363600 (WRKY) may bind to the promoters of critical enzyme genes, or RC1G0363600 (WRKY) may bind to the promoter of RC7G0019000 (MYB) to activate the anthocyanin accumulation in blotch parts of 'Sunset Babylon Eyes'.
Our findings provide a theoretical basis for the understanding of the chemical and molecular mechanism for the formation of petal blotch in rose.
花瓣色斑是被子植物科特有的一种观赏性状，而玫瑰花瓣上的色斑则较为罕见，具有很高的美学价值。然而，玫瑰花瓣色斑形成的原因尚不清楚。需要探索和阐明色素合成途径中关键酶基因和调节基因的影响。
本研究以花瓣基部具玫瑰红至暗红色色斑的玫瑰品种“日落巴比伦之眼”为实验材料。HPLC-DAD 和 UPLC-TQ-MS 分析表明，只有矢车菊素 3,5-O-二葡萄糖苷（Cy3G5G）为“日落巴比伦之眼”的色斑增色，且 Cy3G5G 的含量在不同发育阶段有所变化。在色斑和非色斑部分仅发现类黄酮而没有类胡萝卜素。因此，在花发育阶段，山奈酚及其衍生物以及槲皮素及其衍生物可能作为背景色。尽管组成不同，但色斑和非色斑部分的类胡萝卜素总含量相似，类胡萝卜素可能只是使花瓣呈现更鲜艳的颜色。转录组数据、定量实时 PCR 和启动子序列分析表明，RC7G0058400（F3’H）、RC6G0470600（DFR）和 RC7G0212200（ANS）可能是早期形成和后期色斑颜色加深的关键酶基因。对于两个转录因子，RC7G0019000（MYB）和 RC1G0363600（WRKY）可能与关键酶基因的启动子结合，或者 RC1G0363600（WRKY）可能与 RC7G0019000（MYB）的启动子结合以激活“日落巴比伦之眼”色斑部分的花青素积累。
本研究结果为了解玫瑰花瓣色斑形成的化学和分子机制提供了理论依据。
