RESUMO
The phragmoplast dysfunction in wheat x rye hybrid F1 male meiosis has been described. The pollen mother cells (PMCs) show the phenotype where transition from central spindle fibers (forming a solid bundle) to a phragmoplast (hollow cylinder) is blocked. The blockade suppresses centrifugal movement of the phragmoplast and cell plate formation. The resulting cells occur to be binucleate. Sometimes, the two nuclei join and form one restitution nucleus. PMCs of wheat x rye F1 hybrid N D-144gp 06r. F1 (T. aestivum c. 93-60 T 9 x S. cereale c. Saratovskaya 7) showing this phenotype have an additional phragmoplast at late telophase. This happens like that in the case of immobile phragmoplast formation in meiosis in bicotyledons: the new phragmoplast arises by the aid of microtubules polymerization starting from the spindle poles. The new additional phragmoplast builds a new cell plate and accomplishes cytokinesis.
