Practice question

Different genomes carry distinct inheritance information critical for hybrid verification. Mitochondrial and chloroplast genomes are generally maternally inherited in most angiosperms, representing single parental lineage and low sequence divergence. They often remain uniparental even in somatic hybrids after sorting out, complicating biparental contribution assessment. Nuclear genome, comprising 25,000 to 40,000 genes, follows Mendelian segregation with alleles contributed equally from both parents during syngamy. Co-dominant markers such as microsatellites, SNPs, and ribosomal ITS reveal heterozygous additive patterns confirming true hybridity and allow quantification of genome dosage in allopolyploids. Cytogenetic fluorescent in situ hybridization of genomic DNA also distinguishes parental chromosomes. Because breeding and introgression studies require detection of both parents' contributions, nuclear DNA provides most informative, polymorphic, and appropriate system for definitive hybrid characterization and stability evaluation. Technique includes extraction of total genomic DNA, amplification of nuclear microsatellite loci using fluorescent primers, and analysis on capillary sequencer showing additive allele patterns in hybrids. Compared to chloroplast trnL intron sequencing showing only maternal haplotype, nuclear markers definitively demonstrate biparental contribution and help quantify introgression extent in breeding populations.