First cytogenetic register of an allopolyploid lineage of the genus Aeschynomene (Leguminosae, Papilionoideae) native to Mexico

Abstract

A conventional cytogenetics analysis revealed for first time an allopolyploid lineage of the genus Aeschynomene in Mexico. The hybrid condition is confirmed after all the prometaphase and metaphase nuclei of the hybrids exhibited only one pair of SAT-chromosomes, confirming the existence of nucleolar dominance and amphiplasty. The karyotype formula for this lineage was 2n = 4x = 40 = 34m + 6sm with a total diploid chromosome length (TDCL) = 28µm and an average chromosome size (AC) = 1.40µm. Comparison of the karyotype and other chromosomal parameters with recent cytogenetics records for other species of the subgenus Aeschynomene included in the Nod-independent clade allows propose to Aeschynomene evenia and A. scabra as possible progenitors. Furthermore, other comparison of seedlings focused at the number of leaflets of the first four eophylls of the proposed parents and of the hybrid individuals allowed to observe coincidences that support the proposal made from the cytogenetic analysis. Evidence of "gigas" effects on flowers and fruits of hybrids is also shown.