SEIJO Jose Guillermo
congresos y reuniones científicas
Chromosome structural stability but channelized amphiplasty in AABB allotetraploids of Arachis.
SEIJO J G; CHALUP, L.; SAMOLUK, S; FAVERO, A; ROBLEDO, G.
Congreso; 9th International Conference of the Peanut Research Community on Advances in Arachis through Genomics and Biotechnology (AAGB); 2015
Allopolyploidy is an important evolutionary mechanism in plants. Numerous genetic and epigenetic mechanisms have been shown to generatethe wide range of structural and functional genome modifications associatedwith merged genomes arising from polyploidy events. However, to date little is knownabout the genome interactions that occurred in the AABB tetraploids of Arachis. In this report, we cytologicallyanalyzed three AABB polyploids: the cultivated peanut, the wild A. monticola [both withspontaneous origin (A. duranensis x A. ipäensis) 4x] and one reciprocal synthetic amphidiploid (A. ipäensis x A. duranensis)4x. The patterns (number and position) of heterochromatic DAPI+ bands and the 45S and 5S rDNA mapped by FISH were highly conserved amongthe polyploids and exactly reproduced the sum of those observed in the diploidprogenitors. Telomeric probes hybridized always at the end of the chromosomesand did not reveal any structural rearrangement. Moreover, the occurrence ofintergenomic translocation was not evidenced by GISH analysis. However, in thethree polyploids analyzed the activation of the NORs was biased in favor ofthose belonging to the A genome (A.duranensis). Our results showed a clear pattern of additivity with a strongstructural quiescence at the chromosome level. However, the pattern of rDNAactivation demonstrates that rapid functional changes occurred in the AABBallopolyploids, which involve the differential inactivation of the B genomenucleolar organizing regions (NOR). Moreover, the differential inactivation ofthe B genome NORs occurred irrespective of the species that acted as maternaldonor, suggesting a channelized epigenetic control of these loci.