AUTHOR=Li Huailin , Yu Kaidi , Amoo Olalekan , Yu Yalun , Guo Mixia , Deng Songyue , Li Mengting , Hu Limin , Wang Jingzhen , Fan Chuchuan , Zhou Yongming 

TITLE=Site-Directed Mutagenesis of the Carotenoid Isomerase Gene BnaCRTISO Alters the Color of Petals and Leaves in Brassica napus L.

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.801456

DOI=10.3389/fpls.2022.801456

ISSN=1664-462X

ABSTRACT=<p>The diversity of petal and leaf color can improve the ornamental value of rapeseed and promote the development of agriculture and tourism. The two copies of carotenoid isomerase gene (<italic>BnaCRTISO</italic>) in <italic>Brassica napus</italic> (<italic>BnaA09.CRTISO</italic> and <italic>BnaC08.CRTISO</italic>) was edited using the CRISPR/Cas9 system in the present study. The mutation phenotype of creamy white petals and yellowish leaves could be recovered only in targeted mutants of both <italic>BnaCRTISO</italic> functional copies, indicating that the redundant roles of <italic>BnaA09.CRTISO</italic> and <italic>BnaC08.CRTISO</italic> are vital for the regulation of petal and leaf color. The carotenoid content in the petals and leaves of the <italic>BnaCRTISO</italic> double mutant was significantly reduced. The chalcone content, a vital substance that makes up the yellow color, also decreased significantly in petals. Whereas, the contents of some carotenes (lycopene, α-carotene, γ-carotene) were increased significantly in petals. Further, transcriptome analysis showed that the targeted mutation of <italic>BnaCRTISO</italic> resulted in the significant down-regulation of important genes <italic>BnaPSY</italic> and <italic>BnaC4H</italic> in the carotenoid and flavonoid synthesis pathways, respectively; however, the expression of other genes related to carotenes and xanthophylls synthesis, such as <italic>BnaPDS3</italic>, <italic>BnaZEP</italic>, <italic>BnaBCH1</italic> and <italic>BCH2</italic>, was up-regulated. This indicates that the molecular mechanism regulating petal color variation in <italic>B. napus</italic> is more complicated than those reported in <italic>Arabidopsis</italic> and other <italic>Brassica</italic> species. These results provide insight into the molecular mechanisms underlying flower color variation in rapeseed and provides valuable resources for rapeseed breeding.</p>