THE EFFECT OF THE PH-6 GENE ON THE COLOR OF PETUNIA-HYBRIDA VILM. FLOWERS

An in vivo system was developed to determine the effects of pH on natu rally occurring pigment complexes within cells. The in vivo system was based on a transposable element activator (Ac) inserted into the Phd gene. The transposable element activator (Ac) was crossed into two gen etically marked Petunia hybrida lines expressing known flavonoid pigme nts. Plants expressing the transposable element activator (Ac) produce d variegated flowers in which the background tissue was lighter in int ensity than the sectors. Depending on the genetic background in which the transposable element is expressed, progeny with darker sectors tha t were also redder in color than the background tissue could also be o btained. The anthocyanin and copigment composition was the same for bo th of the differently colored sectors and background tissue, while the pH was lower by 0.4 unit in the redder sectors. It was suggested that the Ph6 gene might be a regulatory gene that controls the expression of the pH and anthocyanin concentration.