Distribution of microtubules during regular and disturbed microsporogenesis and pollen grain development in Gagea lutea (L.) Ker.-Gaw.

The microtubular cytoskeleton in dividing microsporocytes and developing pollen grains of Gagea lutea (L.) Ker.-Gaw.(Liliaceae) was investigated with a modified indirect immunofluorescence method. Meiotic and mitotic stages were identified by DAPI staining. The microtubular cytoskeleton was compared in plants originating from natural localities and others grown in the laboratory. In natural conditions, microsporocytes and pollen grains of wild early-spring Gagea lutea plants are subjected to abiotic factors including cold exposure and lack of water. The persistent influence of these factors can disturb microtubular cytoskeleton functioning. The following disturbances were observed in the course of microsporogenesis and pollen development: abnormal chromosome configurations in the metaphase of meiosis I; abnormally divided dyads with irregular, radial microtubule systems around the nuclei; the formation of differently sized microspores with irregular shapes, and irregular division; and the formation of pollen grains with vacuoles abnormal for their development stage. Similar kinds of disturbances were observed after 1.5 months of cold treatment (4 ^{\circ}C) and drying in the laboratory. These abiotic factors simulated in laboratory conditions caused more disturbances in the course of microsporogenesis and produced more frequent defective pollen grains than in the sample that had experienced cold and drying in natural conditions.