A new study on the rare blue petunia could help researchers learn to control the appearance of ornamental flowers and even hints of flavor in wines and fruit.
The research also looked at how flower color could attract (or fail to attract) pollinators, a Cell Press news release reported.
The secret behind the blue petals is the failure of a "cellular pump" that went unnoticed by researchers. If the pump malfunctions in petunias it can keep certain cell compartments within the flower from properly acidifying; turning the petals a blue or violet hue.
"Blue flower colors have been enigmatic for a long time and the blue rose appears in many myths, legends, and even operas," Francesca Quattrocchio of the VU-University in Amsterdam, said in the news release." Already in the 1910s it was proposed that blue flower colors were caused by reduced acidity of the 'cell sap.' Others figured that drastic changes in the cell sap might cause terrible deleterious defects, and proposed that blue flower colors had something to do with the formation of metal-anthocyanin complexes. Our current opinion is that both got it right."
Scientists did manage to discover one type of "proton pump" back in the 1980s.
"Over the decades, the idea took hold that all H+ transport across internal membranes is driven by those v-ATPases," Ronald Koes of VU-University in the Netherlands said.
Most cells only exhibit a slight difference in pH between the inside and outside their intracellular compartments (vacuoles). In petals this difference is more pronounced. The research team determined the differences between pH in red and blue petunias were based on certain PH genes.
"Those genes encode a proton-pumping pathway that allows petal cells, and perhaps other cells as well, to hyperacidify particular compartments. The pump is composed of two distinct proteins, which together keep on going -- and building acidity -- even when other pumps would stop," the news release reported.
The researchers determined blue petunias are actually so rare because the characteristic is caused by a genetic defect that breaks down the pumping system.
"By studying the difference between blue and red flowers of petunias, we have discovered a novel type of transporter able to strongly acidify the inside of the vacuole," Quattrocchio said.
The researchers hope to use their new knowledge of how pH affects color to manipulate the color and taste of plants in the future.