DNA content, Fundamental Number and Karyotype changes in Tribe Leucocoryneae (Amaryllidaceae, Alliodeae) .

SASSONE, AGOSTINA B.; LOPEZ, ALICIA; GIUSSANI, LILIANA MONICA

Forth Worth, Texas

Congreso; Botany Conference 2017; 2017

The tribe Leucocoryneae (Amaryllidaceae,Alliodeae) is monophyletic and composed by 6genera, with ca. 100 species exclusivelydistributed in South America, except forNothoscordum, which is widespread in South Americawith one species extended to North America. TribeLeucocoryneae includes the monophyletic genera:Ipheion (x= 5, 6, 7), Latace (x= 12), Leucocoryne(x= 5), and Tristagma (x= 4), and?Notoscordum + Beauverdia?. OnlyNothoscordum sect. Inodorum (x= 5) is monophyleticand Beauverdia (x= 5) is nested within N. sect.Nothoscordum (x= 4, 5). A wide variation incytogenetic parameters has been accumulated duringevolution; for instance, the ploidy level rangesfrom diploid to hexaploid, the fundamental numberranges from 14 to 48, and the karyotype formulashows metacentric, submetacentric and acrocentricchromosomes. Here, we elucidate the evolution oftribe Leucocoryneae from a cytogenetic approachwith the following aims: (1) to estimate thegenome size of species of Leucocoryneae; (2) toanalyze the patterns of genome size variation; and(3) to investigate the impact of karyotypeevolution on the distribution of total DNAcontent. Nuclear DNA content was assessed in 18species using fresh young leaves from cultivatedmaterial or silica gel dried leaves by propidiumiodide (PI) flow cytometry assay. For eachspecies, the mean value of 2C was obtained frommeasurements of at least three specimens. Nucleiof Ipheion uniflorum (2n=2x=12, 2C=19.3 pg) wereused as internal standards. Monoploid genome sizes(1Cx) were calculated from 2C, and ploidy level(reported in previous literature). As a result,total DNA content in genera of Leucocoryneae rangefrom 19 to 77 pg., being 15 folds of the averagein Angiosperms; Cx content varies among genera andspecies: Beauverdia ranges from 13.05 to 17.9pg; Ipheion ranges from 9.07 to 9.65 pg.; Lataceandina 18.6 pg.; Nothoscordum varied from 11.8 pgto 23.7 pg.; and Tristagma from 15.3 to 17.7 pg. Moreover, total DNA content was analyzed in aphylogenetic context, and it is inferred thatconservation or reduction of genome size is aproduct of poliploidization and/or robertsoniantraslocations.