Cytotaxonomy of Tripogandra diuretica and Tripogandra glandulosa (Commelinaceae) from NE Argentina

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.

Keywords:

• Chromosomes
• cytogenetics
• evolution
• taxonomy
• Tripogandra

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.