An Acetocarmine Staining Procedure for Chromosome Banding Studies of Immature Pollen in Triticeae

Studies of postmeiotic chromosomes have been impeded by the thick exine of immature pollen grains. Chromosome staining of immature and adult pollen grains through conventional acetocarmine procedure is tedious and often leads to unsatisfactory results. An acetocarmine stain, used in conjugation with Carnoy’s solution as fixative for 72 hrs or until the chlorophyll-containing tissues of spike became colorless, were successfully used to stain chromosome bands and nucleoli of the immature pollen grain in Aegilops cylindrica. Mitosis of immature pollen exhibited several remarkable features, one being the distinguishable haploid chromosome set of immature pollen. Only one of two nucleolus organizer regions of Ae. cylindrica produced nucleolus at the prophase of first pollen mitosis. An acetocarmine-banded karyotype with only minor variations in the acetocarminebanding pattern was revealed within and between plants of the accession of Ae. cylindrica. Some of banding patterns in the chromosome complement was identical to marker Cbands or accession-specific bands in corresponding genome in Ae. caudata (CC) or Ae. squarrosa (DD). The reliability of the acetocarmine banding for Triticeae chromosome identification is discussed.