Pisum spp. exhibit polymorphism for the number of secondary constrictions: P. sativum contains two pairs of satellited chromosomes (4 and 7), while P. fulvum has three pairs (4, 5 and 7). The satellite of chromosome 7 is longer in P. fulvum than in P. sativum. Reconstructions were obtained in chromosomes 5 and 7 through interspecific hybridization between P. sativum and P. fulvum, followed by five backcrosses with P. sativum as recurrent parent. Modified chromosomes 5 and 7 showed an additional secondary constriction and a longer satellite, respectively. A deficiency of backcross plants carrying the additional NOR on chromosome 5 was observed, the segregation showing a significant deviation from the expected 1 : 1 ratio. This deficit was not related to the chromosome interchanges observed in the material. Near all the plants with modified chromosome 5 presented modified chromosome 7, suggesting that the simultaneous presence of both the modofied chromosomes recovers a genic equilibrium, allowing the development of plants with chromosome reconstructions. The chromosome reconstructions were not associated with any noticeable morphological characteristic
Chromosome reconstructions in P. sativum through interspecific hybridization with P. fulvum.
Conicella C;
1996
Abstract
Pisum spp. exhibit polymorphism for the number of secondary constrictions: P. sativum contains two pairs of satellited chromosomes (4 and 7), while P. fulvum has three pairs (4, 5 and 7). The satellite of chromosome 7 is longer in P. fulvum than in P. sativum. Reconstructions were obtained in chromosomes 5 and 7 through interspecific hybridization between P. sativum and P. fulvum, followed by five backcrosses with P. sativum as recurrent parent. Modified chromosomes 5 and 7 showed an additional secondary constriction and a longer satellite, respectively. A deficiency of backcross plants carrying the additional NOR on chromosome 5 was observed, the segregation showing a significant deviation from the expected 1 : 1 ratio. This deficit was not related to the chromosome interchanges observed in the material. Near all the plants with modified chromosome 5 presented modified chromosome 7, suggesting that the simultaneous presence of both the modofied chromosomes recovers a genic equilibrium, allowing the development of plants with chromosome reconstructions. The chromosome reconstructions were not associated with any noticeable morphological characteristicI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
