No abstract

No abstract

No abstract

Pollen mother cell (PMC) development in the apomictic Boechera species B. holboellii, B. gunnisoniana and B. divaricarpa were investigated by various cytological methods. In prophase I, in triploid species B. holboellii and B. gunnisoniana the individual chromosomes condensed into long strands within the nucleus. Then, in metaphase I, each PMC formed a restitutional nucleus thereby bypassing the rest of the first meiotic division. This is interpreted as representing apomeiosis. Subsequently, the restitution nuclei underwent a single cytokinesis as evidenced by the production of dyads. The cells within each dyad were separated by a callose wall. Most of the PMC in B. holboellii and B. gunnisoniana produced dyads, but a small proportion generated conspicuous tetrads. In contrast, diploid apomict B. divaricarpa produced only tetrads by simultaneous cytokinesis.Additional key word: apomixis, endosperm, male gametes.

BACKGROUND: Identification of genotypes in Salvia is complicated owing to the morphological similarity and common occurrence of natural hybridisation within Salvia species. Species-and genotype-specific DNA markers are very useful for plant identification, breeding and preservation programmes and can also provide a general overview on the prediction of plant essential oil yield.