The Groundsman

September 2016

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Visit www.iog.org for more information and digital editions TECHNICAL UPDATE 24 the Groundsman September 2016 loidy Ploidy refers to the number of complete sets of chromosomes within the nucleus of each plant cell. Polyploid plants contain more than two sets of chromosomes within each cell. Chromosomes are thread-like structures arranged in linear pairs. Each chromosome is made of protein and a single molecule of hereditary DNA (deoxyribonucleic acid) wrapped around the protein. Polyploidy is naturally occurring in many wild and cultivated plant species, including grasses like fine fescues, which can be hexaploid or octaploid. Polyploidy can also be induced in plants through the application of a natural alkaloid plant hormone colchicine, derived from Colchicum autumnale (Autumn Crocus). P What is a tetraploid? We look at the technology of tetraploid perennial ryegrasses, which are highly valued for their fast establishment, cool temperature recovery, high root mass and greater stress tolerance By: Jayne Leyland Colchicine acts as a mitosis inhibitor, resulting in chromosome doubling within each cell, thus diploid (2n) becomes tetraploid (4n). Induced polyploidy Perennial ryegrasses bred and developed for amenity use are historically diploid, having two paired sets of chromosomes within each cell. Tetra is the Greek translation for four, meaning tetraploids have four paired sets within each cell, a physiological characteristic that delivers such exceptional benefits to the plant. Mitosis is a part of the cell cycle in which chromosomes in the cell nucleus are separated into two identical sets, each paired set ending up inside an identical diploid cell. Microtubules are microscopic structures that help cells maintain their shape and assist in forming the cell spindle which, during cell division, divides the chromosomes into pairs. In the creation of a tetraploid, the hormone disrupts the microtubules, preventing formation of the spindle that divides the genetic material. The process of mitotic polyploidy results in cell enlargement, doubling the sets of chromosomes (four pairs) in each new daughter cell. Superior winter wear and robust re-growth helps keep surfaces in play though the winter high-pressure period " " Chromosome counting in the laboratory

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