Chromosome studies in Orchidaceae from Argentina

Abstract

The center of diversity of Argentinean orchids is in the northeast region of the country. Chromosome numbers and karyotype features of 43 species belonging to 28 genera are presented here.

Comparative cytogenetics in Cyclopogon (Orchidaceae)

“…It is a diploid taxon with 2n = 28 chromosomes. In agreement, Daviña et al (2009) reported the same number and Grabiele et al (2011a) found a regular meiotic behavior and n = 14 bivalents for these Argentinian accessions of C. calophyllus. The karyotype, composed by 18m + 10sm chromosomes, is unimodal (A 2 = 0.20; R = 1.92) and symmetrical (A 1 = 0.32; r>2 = 0.29; i = 40.01) and belongs to Stebbins' category 2A; the pair no.…”

“…It is a diploid species displaying 2n = 28 chromosomes. In agreement, Daviña et al (2009) reported the same number and Cerutti et al (2004) found a regular meiotic behavior and n = 14 bivalents for these Argentinian accessions of C. elatus. Other counts in this taxon found n = 14 bivalents and 2n = 28 for NE Argentina plants, in addition to 2n = 30 and 2n = 45 (45?, see below) for Brazilian and Misiones materials, respectively (Martinez 1981) added to 2n = 28 from NE Brazil populations (Felix & Guerra 2005).…”

“…It is a diploid taxon showing 2n = 32 chromosomes. In agreement, Daviña et al (2009) reported the same number for these Argentinian accessions of C. congestus. Other counts in plants from Misiones constantly established 2n = 32 additionally to n = 16 bivalents [Martinez 1981; as Beadlea congesta (Vell.)…”

“…Karyological data in Cyclopogon is scarce with only eight species from N Argentina, Brazil and Peru chromosomally studied, displaying a wide diversity in chromosome numbers and ploidy levels ranging from 2n = 28 to 66 (Martinez 1981(Martinez , 1985Tanaka & Maekawa 1983;Felix & Guerra 2005;Daviña et al 2009). Meiotic analysis carried out in five taxa of this genus showing 2n = 28, 32 or 64 chromosomes found a regular behaviour and n = 14, 16 or 32 bivalents exclusively, respectively (Martinez 1981;Cerutti et al 2004;Felix & Guerra 2005;Grabiele et al 2011a).…”

“…Meiotic analysis carried out in five taxa of this genus showing 2n = 28, 32 or 64 chromosomes found a regular behaviour and n = 14, 16 or 32 bivalents exclusively, respectively (Martinez 1981;Cerutti et al 2004;Felix & Guerra 2005;Grabiele et al 2011a). Nevertheless, a deep karyotipic characterization of Cyclopogon is still missing with some contributions made by Martinez (1981Martinez ( , 1985, Tanaka & Maekawa (1983), Felix & Guerra (2005) and Daviña et al (2009) which a priori reveal primary structural differences respecting the related taxa in Spiranthinae largely based on x = 23 (Grabiele et al 2010(Grabiele et al , 2011b. However, questions of the origins of the observed chromosome numbers diversity, the fundamental karyotipic differences and the basic chromosome number of Cyclopogon remain unsolved.…”