Abstract
Pollen, the angiosperm male gametophyte is composed of three haploid cells, namely, a single vegetative cell and two enclosed sperm cells. During pollen maturation, drastic degradation of organellar DNA in the vegetative cell can be visualized by staining pollen with a DNA-specific fluorescent dye such as 4,6-diamidino-2-phenylindole (DAPI). This degradation results in the exclusion of organellar DNA from male gametophytes and could contribute to maternal inheritance of organellar genome. However, the regulatory mechanism and the underlying biological significance of organellar DNA degradation in vegetative cells remain unclear. Our laboratory has screened for mutants defective in pollen organellar DNA degradation (dpd). One of the mutants obtained, dpd2, show pleiotropic phenotypes. The DPD2 gene encodes one of the enzymes involved in nucleotide biosynthesis. Interestingly, we found that other nucleotide biosynthesis pathway-related mutants exhibit pollen organellar DNA degradation phenotypes similar to dpd2. Our study suggests that there is interplay between organellar DNA degradation and nucleotide de novo synthesis during pollen maturation.
