Stage heterogeneity of generative and vegetative cells in pollen grains of dehiscent anthers of two cultivars ofMalus domestica Borkh: “Golden Delicious” and “Starkrimson”

Summary

Pollen grains of dehiscent anthers of two cultivars ofMalus domestica “Golden Delicious” (partially self-incompatible) and “Starkrimson” (self-incompatible) were studied by Feulgen cytophotometry and starch staining. The collected results show:

• I) in both cultivars generative cells in G₁ (DNA content/nucleus 1 c) and in G₂ (DNA content/nucleus 2 c) are present;

• II) in both cultivars vegetative cells may be characterized by the lack of starch, or by its presence in variable amount;

• III) when single pollen grains are considered, G₁ and G₂ generative cells can be present in concomitance with starch free or with starch containing vegetative cells.

On the basis of the above data it is concluded that the starch synthesis begins in the vegetative cell during the G₁ phase of the generative cell. The rate of synthesis increases during the G₁ itself and obviously remains constant during early G₂. The late G₂ generative cells coexist with starch free vegetative cells (mature pollen grains).