title: Cell division versus cell elongation: the control of radicle elongation during thermoinhibition of Tagetes minuta achenes.
abstract: Endogenous embryo factors, which act mainly in the radicle, prevent germination in Tagetes minuta at high temperatures. These factors act to prevent cell elongation, which is critical for radicle protrusion under optimal conditions. Once the radicle has emerged both cell elongation and cell division are required for post-germination growth. Germination can be induced at high temperatures by fusicoccin, which rapidly stimulates cell elongation. In addition, priming seeds at 25 degrees C on polyethylene glycol (PEG) 6000 and mannitol could also induce germination on water at 36 degrees C, indicating that priming prevents radicle protrusion at a point subsequent to the point of control in thermoinhibited achenes. Flow cytometry studies revealed that DNA synthesis occurs during thermoinhibition and the inhibition of DNA synthesis during this process inhibits subsequent germination on water under optimal conditions, suggesting a protective role for DNA synthesis in thermoinhibited achenes of T. minuta.
authors.affiliation: Research Centre for Plant Growth and Development, School of Biological and Conservation Sciences, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa.
authors.forename: Nicky J
authors.initials: NJ
authors.lastname: Taylor
authors.forename: Paul N
authors.initials: PN
authors.lastname: Hills
authors.forename: Johannes
authors.initials: J
authors.lastname: van Staden
mesh_terms: D002455:Cell Division / Q000187:drug effects; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D048429:Cell Size / Q000187:drug effects; D018744:DNA, Plant / Q000032:analysis; D005030:Ethylenes / Q000494:pharmacology; D018525:Germination / Q000187:drug effects; D006027:Glycosides / Q000494:pharmacology; D018517:Plant Roots / Q000166:cytology* / Q000187:drug effects; D006180:Proton-Translocating ATPases / Q000378:metabolism; D011728:Pyridones / Q000494:pharmacology; D012639:Seeds / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development; D031686:Tagetes / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology; D013696:Temperature
chemical_list: D018744:DNA, Plant; D005030:Ethylenes; D006027:Glycosides; D011728:Pyridones; C007808:fusicoccin; C013351:fluridone; C036216:ethylene; D006180:Proton-Translocating ATPases