Abstract
Parallel spindles occur during microsporogenesis in the cultivar Sebago (2n=4x =48) and are the basis of 2n pollen production in this clone. The relations between the frequencies of parallel spindles, 2n microspores, and 2n pollen are striking. The predicted frequency of 2n pollen based on the percentage of microsporocytes with parallel spindles is highly correlated with the frequency of 2n pollen observed. The percentage of 2n microspores at the sporad stage also corresponds very closely with the observed percentage of 2n pollen. Sebago is thus nulliplex (psp sp sps) for the meiotic mutant which governs spindle orientation at the second meiotic division in microsporocytes. This finding agrees with the prediction that if parallel spindles were involved in the origin of cultivated tetraploid potatoes, the genesps should be present in some 4x cultivars. It adds further support to the concept that 2n gametes have been a creative factor in the origin and evolution of cultivated tetraploids.
Resumen
Husos paralelos ocurren durante microsporogenesis en el cultivar Sebago (2n = 4x =48) y constituyen la base para la production de polen 2n en este clon. Es saltante las relaciones que existen entre la frecuencia de husos paralelos, microsporas 2n y polen 2n. La predicción de polen 2n basado en el porcentaje de microsporocitos con husos paralelos es altamente correlacionada con la frecuencia de polen 2n observado. El porcentaje de microsporas 2n al estado de esporas también corresponde muy cerca con el porcentaje de polen 2n. Sebago es entonces nuliplex (ps ps ps ps) para el mutante meiótico que contróla la orientación del huso acromático en la segunda división meiótica de los microsporocitos. Este hallazgo está de acuerdo con la predicción en que si husos paralelos están involucrados en el origen de las papas cultivadas tatraploides, el geneps debería estar presente en algunos cultivares YX. Esto añade soporte adicional al concepto en que gametos 2n han sido un factor creativo en el origen y evolución de las papas cultivadas tetraploides.
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Paper #2301 of the Laboratory of Genetics. Research supported by Beloit College Science Faculty Research Fund, UW-Madison College of Agricultural and Life Sciences, and The National Science Foundation (PCM 77-24330).
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Souter, E.W., Dawe, J.C. & Peloquin, S.J. 2n pollen formation via parallel spindles in the potato cultivar sebago. American Potato Journal 57, 449–455 (1980). https://doi.org/10.1007/BF02854460
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DOI: https://doi.org/10.1007/BF02854460