Abstract

GARDUNO VELAZQUEZ, Santiago et al. Ploidy level in native populations of Leptochloa dubia (Kunth) Nees from Mexico. Rev. Mex. Cienc. Agríc [online]. 2015, vol.6, n.3, pp.539-548. ISSN 2007-0934.

Leptochloa dubia (Kunth) Nees is a perennial forage grass, native to north-central Mexico, adapted to all regions of scarce precipitation, its basic chromosome number is x= 10 and its ploidy level from diploid (2n= 2x= 20) to octoploide (2n= 2x= 80). The objective was to determine the chromosome number and ploidy level of a collection of 67 populations of green sprangletop, collected during 2009 in the Mexican plateau between 19º to 28º north latitude and 1 500 a 2 450 masl. Chromosome counts were made in root tips actively growing (5 to 10 mm), treated with 8-hydroxyquinoline (2 mM) for 3.5 h, fixed in solution (3: 1 v / v absolute ethanol and glacial acetic acid) and stored at 4 °C until evaluation. Chromosome counting was made on a phase contrast microscope. Cells in metaphase were observed, at least, five preparations and 10 cells per preparation, for each plant and population. 96% of the analized plants were tetraploid 2n= 4x= 40 and 4% diploid 2n= 2x= 20. Diploid plants were from six populations of Hidalgo, Guanajuato and the border between Aguascalientes, Jalisco and Guanajuato; tetraploid plantswere found in all populations evaluated; however, no significant differences were found among sites (p< 0.05), according to their ploidy level. The levels found are indicative of the broad center of origin of this species.

Keywords : Leptochloa dubia; chromosomes; diploid; tetraploid.

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