Genome size, karyotypic features and pollen size in Argentinian species of Spergula (Caryophyllaceae).

Abstract

Genome size, karyotypic features and pollen size in Argentinian species of Spergula (Caryophyllaceae). The objective of this work was to estimate the DNA content (2C) in four species of Spergula that inhabit Argentina and to analyze the variation of genome size (Cx) in relation to karyotypic and palynological features. The DNA content of five taxa and the genome size of four, which varied very little between species, were analyzed for the first time from Cx= 0.458 pg (S. salina, 4x) to Cx= 0.856 pg (S. arvensis, 2x). Two new chromosomal counts were recorded for the genus and the pollen size varied from small to medium. The regression coefficients suggest that the chromosome number varies inversely proportional in regards to the genome size, while the genome size presents a low relation with the total chromosome length (TCL) of the diploid genome, although it shows a high relation with respect to the average chromosome length (ACL). Meanwhile, the pollen size varies independently regarding to the genome size. The detected karyotypic variation could be due by numerical and structural changes during the genus evolution, while the pollen size could be related with selection pressures associated with dispersal strategies.