SEIJO Jose Guillermo
Karyotype Stability and Genome-Specific Nucleolar Dominance in Peanut, Its Wild 4× Ancestor, and a Synthetic AABB Polyploid
SEIJO, JOSÉ GUILLERMO; KOVALSKY, EVELIN IVANA; CHALUP, LAURA MARÍA ISABEL; SAMOLUK, SERGIO SEBASTIÁN; FÁVERO, ALESSANDRA; ROBLEDO, GERMÁN ARIEL
CROP SCIENCE SOC AMER
Lugar: Baltimore; Año: 2018 vol. 58
Allopolyploidy is a significant evolutionaryprocess involved in the origin of many crops,including peanut (Arachis hypogaea L.). Theprocess usually results in a series of chromosome,genomic and epigenetic rearrangementsin the derived polyploids. Here, we examinedthe chromosomal consequences undergone byAABB tetraploids of Arachis after the genomemerger. For that objective, different chromosomemarkers and DNA contents were comparedamong peanut, its wild tetraploid ancestor, andthe diploid genome donors A. duranensis Krapov.& W.C. Gregory (AA, female) and A. ipaënsisKrapov. & W.C. Gregory (BB, male). The analysisalso included an artificially synthesized allotetraploidusing A. ipaënsis as a female [(A. ipaënsis´ A. duranensis)4´]. The karyotypes in the natural(originated ?10,000 yr ago) and newly synthesizedallopolyploids have largely maintainedthe patterns of heterochromatin and ribosomalRNA loci detected in the diploid progenitors.Intergenomic translocations were not evidentusing genome in situ hybridization, and the DNAcontents of the allotetraploids correspondedto the expected sum of those observed in theirparental species. The analysis of ribosomal DNAloci and their association with nucleolar organizingregions revealed a rapid establishment ofnucleolar dominance in favor of the A genome.The large macrostructural stability of karyotypeobserved here after polyploidization has notbeen frequently cited for polyploid crop plants.This stability is significant for peanut breeding,since it suggests that effective introgression ofwild useful alleles into cultivated peanut maypotentially occur in most of the extension of theA and B chromosome complements.