Submitted to: Journal of Heredity
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/10/2007
Publication Date: 1/21/2008
Citation: Peloquin, S.J., Boiteux, L.S., Simon, P.W., Jansky, S.H. 2008. A chromosome-specific estimate of transmission of heterozygosity by 2n gametes in potato. Journal of Heredity. 99(2):177-181. Interpretive Summary: This manuscript compares estimates of how genes and genetic variation is passed from one generation to the next based upon 2 ways of making those estimates: by looking at chromosomes and by looking at data that measures genetic variation. The paper tests six models based on different assumptions about chromosome structure. The model produced results similar to the data that have been collected. One type of abnormal meiosis was more effective than another for transmitting genetic variability to offspring. This manuscript presents information of interest to geneticists and plant breeders in associating chromosome observations to genetic data.
Technical Abstract: Polyploid plants are formed when numerically unreduced (2n) gametes participate in fertilization. Based on cytological and genetic analyses, modes of 2n gamete formation have been determined for a number of plant species. Gametes formed by a first division (FDR) restitution mechanism contain non-sister chromatids near the centromere, while those formed by second division restitution (SDR) contain sister chromatids. These mechanisms differ in the proportion of heterozygous loci they transmit intact to offspring. This paper estimates the transmission of heterozygosity on an individual chromosome basis through pachytene analysis of chromosomes of haploids (2n=2x=24) of Solanum tuberosum Andigena Group (2n=4x=48), a South American cultivated potato. Transmission of heterozygosity by FDR and SDR 2n gametes was calculated for six different cytogenetic assumptions. FDR was more than twice as effective as SDR in transmission of heterozygosity under all six scenarios. Rates of transmission of heterozygosity were similar in each situation. Transmission of heterozygosity by FDR was also compared to transmission of heterozygosity by tetrasomic inheritance and found to be approximately 50% more effective.