Microtubule and male sterility in a gene-cytoplasmic male sterile line of non-heading Chinese cabbage.

BACKGROUND: Microtubules are the basic components of the cytoskeleton in eukaryotic cells and are made up of 13 parallel protofilaments, each composed of α- and β-tubulin unit molecules aligned along the longitudinal axis of the microtubule.
RESULTS: α-Tubulin gene TUBA2 from non-heading Chinese cabbage (Brassica campestris ssp. chinensis Makino) was expressed at the highest level in stamens and at lower levels in other organs. In addition, it was expressed at a much lower level in the cytoplasmic male sterile (CMS) line than in the maintainer line. Furthermore, at the microsporocyte stage of development in the CMS line the microtubule bundles were knitted together in random organisation, which differed significantly from the radiate microtubule bundles running circumferentially around the nucleus in the maintainer line. Also, large vacuoles appeared within the cytoplasm in the CMS line with no dyed microtubules.
CONCLUSION: TUBA2 was very important to pollen development, which might be closely related to male sterility. Large vacuoles might replace the nuclei close to the cell walls and lead to a lack of microtubules when the cells abort. Abnormalities and defects in the organisation and composition of microtubules in the male sterile line highlighted the complex interaction between microtubules and cytoplasmic male sterility.