Karyotype stability and genome specific nucleolar dominance in peanut, its wild 4x ancestor and in a synthetic AABB polyploid

CHALUP LMI; ROBLEDO G.; CHALUP LMI; ROBLEDO G.; SEIJO JG; SAMOLUK SS; SEIJO JG; SAMOLUK SS; KOVALSKY I.E.; FAVERO A; KOVALSKY I.E.; FAVERO A

CROP SCIENCE

CROP SCIENCE SOC AMER

Lugar: Baltimore; Año: 2018 vol. 58 p. 1 - 13

0011-183X

Allopolyploidy is a significant evolutionary process involved in the origin of many domesticated crops. The process usually results in series of chromosome, genomic and epigenetic rearrangement of the derived polyploids. Here we examined the chromosomal consequences of genomic merger in the AABB tetraploids of Arachis. For that purpose, different chromosome markers and DNA contents were compared among the cultivated peanut, and a natural tetraploid (A. monticola) originated from A. duranensis and A ipaënsis around 10000 BP. The markers were also analyzed in a reciprocal allotetraploid [(A. ipaënsis x A. duranensis)4x] recently synthetized. The pattern of heterochromatin (DAPI+) and rRNA gene (FISH) detected in the natural and synthetic allopolyploids were the sum of the patterns observed in the diploid progenitors. GISH analysis did not evidence any large intergenomic translocation and DNA contents of the allotetraploids were nearly the sum of the contents observed in their parental species. However, the analysis of rDNA loci revealed that those belonging to the A genome were preferentially active while those of the B genome were inactive in all the polyploids analyzed, irrespective to their maternal genome donor. The results evidenced a high structural additivity at chromosome level in the AABB Arachis tetraploids, but a rapid establishment of nucleolar dominance in favor of the A genome rDNA loci.