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Independently Segregating Simple Sequence Repeats (SSR) Alleles in Polyploid Sugarcane
- Yong-Bao Pan, Pingwu Liu, Youxiong Que
- Sugar tech 2014 pp. 1-8
- Saccharum, alleles, capillary electrophoresis, cultivars, flowers, gene segregation, genetic markers, genotype, genotyping, hybrids, microsatellite repeats, nuclear genome, pollen, polyploidy, progeny, sugarcane
- The complex nuclear genomic and flower structures of sugarcane cultivars (Saccharum hybrids spp., 2n = 10x = 100–130) render sugarcane a difficult subject for genetics research. Using a capillary electrophoresis and fluorescence-labeling-based simple sequence repeat (SSR) genotyping platform, the segregation of a multiallelic sugarcane SSR marker SMC336BS was investigated among single pollens of a sugarcane cultivar L 99-233 as well as its F1 progenies of a bi-parental cross between HoCP 00-950 (female) and L 99-233 (male). L 99-233 produced five reproducible SSR alleles, namely, 6-154, 6-167, 6-169, 6-171, and 6-175, while HoCP 00-950 produced two SSR alleles, 6-166 and 6-169. Of these six parental alleles, 6-167, 6-169, 6-171, and 6-175 were detected in approximately half of the pollens indicating an independent Mendelian segregation. In addition, four alleles, namely, 6-154, 6-166, 6-167, and 6-175, were detected in approximately half of the F1 progenies, again an indication of independent Mendelian segregation. Twenty-two pollen genotypes were observed among 92 single pollens at frequencies varying from 1.08 to 11.83 % and 33 genotypes were observed among 162 F1 progenies at frequencies varying from 0.62 to 8.64 %. Although none of the 92 single pollens amplified all five parental alleles, one F1 progeny produced all the six parental alleles. Unexpected segregation patterns were also observed. Allele 6-171, which was absent in HoCP 00-950, segregated at 3 presence:1 absence instead of expected 1:1. Allele 6-169, which was detected in both cultivars and segregated at 1:1 among pollens, segregated at nearly 1:0. These unexpected segregation patterns may be associated with the complexity of sugarcane genome and illustrate the needs of additional genetic studies in polyploid sugarcane.