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Abstract
Karyotype features and microsporogenesis of Tripogandra diuretica (Mart.) Handlos and Tripogandra glandulosa (Seub.) Rohw. from 15 NE Argentina accessions are analysed via classical cytogenetics, CMA/DA/DAPI and Ag-NOR. The karyotype of T. glandulosa (2n = 2x = 16; 2m + 6sm + 8st) is bimodal (A 2 = 0.37; R = 2.65) and asymmetrical (A 1 = 0.63; i = 26.06; r > 2 = 0.88) (3B-Stebbins) with a genome size of 33.28 μm; two pairs are satellited, CMA+ and NOR-actives. Another four CMA+ loci and DAPI+ universal centromeric heterochromatin occur. Microsporogenesis is normal (pollen viability short stamens = 97.8%; large = 96.7%), meiotic behaviour is regular and chromosomes pair as 8II. The karyotype of T. diuretica (2n = 8x = 64; 8m + 24sm + 32st) is bimodal (A 2 = 0.27; R = 2.54) and asymmetrical (A 1 = 0.60; i = 27.32; r > 2 = 0.88) (3B-Stebbins); additionally, two pairs are satellited. Microsporogenesis is normal (short stamens = 77.8%; large = 68.5%), except for micronuclei and low pollen viability in some accessions. Meiotic behaviour is regular with 32II, acting as a cytological diploid, however the arrangement of the haploid karyotype suggests that T. diuretica, which also exhibits a reduction of the genome size (18.58 μm), constitutes an auto-octoploid taxa. Additionally, both species share cytological features common to karyotype orthoselection.
Acknowledgements
This study was supported by Agencia Nacional de Promoción Científica y Técnica (ANPCyT) grant no. PICT-O 36907 and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), both from Argentina.