Studies on Petunia. VI. The Origin and Distribution of Color in the Anther and in the Pollen of Petunia

Abstract

Listen

Translate article

1. Throughout this paper, all conditions described or conclusions reached are meant to apply only to those species or strains of Petunia which we are growing in our cultures, even though such a limiting phrase may be omitted. At the same time we feel that our observations have probably covered a sufficiently wide range of forms to be of rather general application within the genus. 2. All cells of the very young anthers, except those of the connective, carry chlorophyll. 3. As the chloroplasts are lost, the yellow pigment of the older anthers and of the pollen is initiated. 4. No matter what the color of the mature anther and pollen may be, yellow pigment is always present in them although frequently masked by anthocyanin. 5. The yellow pigment falls into three groups as to solubility, a portion being soluble in water, a second portion soluble in alcohol, and a third portion insoluble in all liquids to which it was subjected. 6. The presence of two flavones is demonstrated. 7. Color, other than green or yellow, first appears in the sterile tissue at the inner side of each of the four microsporangia. It is in solution in the cell sap. 8. This pigment is always a magenta red and is soluble in all the media in which it was mounted. It is evidently not an anthocyanin. 9. True anthocyanin appears just prior to the dehiscence of the anther. It is first seen in connection with the cells, containing the magenta cell sap, at either end of the sterile plate and from thence progresses outward into the wall. 10. The magenta pigment is evidently closely associated with the origin of the anthocyanin. 11. Both a red and a blue anthocyanin is present. 12. In uniformly colored anthers the anthocyanin may be present in all the cells of the anther with the exception of the connective. 13. With a mosaic distribution of the pigment in the anther, no anthocyanin has been observed in the endothecium. 14. Color is present in both the walls and the contents of the pollen grains. 15. In markedly heterozygous diploids and in polyploids, the color of the pollen is further strengthened by the presence of special color bodies. 16. All the evidence points toward a common origin of pigment in the anthers and in the pollen.