Mechanisms underlying flower color variation in Asian species of Meconopsis: A preliminary phylogenetic analysis based on chloroplast DNA and anthocyanin biosynthesis genes.

The Qinghai-Tibet Plateau (QTP) harbors the highest species diversity of alpine plants in the world, with a spectacular diversity of flower colors. Among these QTP plants, the genus Meconopsis comprises more than 50 species, for which flower color is a key diagnostic character. However, the mechanisms underlying flower color variation have rarely been investigated. In the present study, we used three chloroplast (cp) DNA fragments and two anthocyanin biosynthesis genes ( F3H and F3′ H) for phylogenetic reconstruction of Meconopsis. We revealed the presence of three well-supported clades and/or subclades in the cpDNA and nuclear gene trees; further, flower color transition occurred in each lineage. The results of selection tests and preliminary expression analyses of the anthocyanin biosynthesis genes indicate that the pigment pathway leading to cyanidin is active in blue and red flowers of Meconopsis; further, a blue-red color shift is not attributable to an on/off switching of the anthocyanin biosynthetic pathway (ABP) branches. Together with the results of previous flower pigment analyses, our findings suggest that blue-red flower color transitions in Meconopsis are attributable to modification of cyanidin. Our molecular dating results indicate that the lineage diversification in Meconopsis is closely related to the QTP uplift; thus, it is likely that environmental changes arising from the QTP uplift have played important roles in driving the diversification of flavonoids, through which species of Meconopsis have adapted physiologically to diverse habitats. [ABSTRACT FROM AUTHOR]