Loss of nuclear DNA in leaves of rye.

The nuclear DNA content of rye leaf cells was cytophotometrically determined. At the commencement of differentiation nuclei in rye leaves remain standing at G1 phase. With further differentiation a remarkable diminution of nuclear DNA content occurs in diploid cells. The largest number of cells showing a loss of nuclear DNA content were found in the top of the leaf. The age of the leaf and the extent of diminution in nuclear DNA content are correlated.