INDUCCIÓN DE TETRAPLOIDES EN Agave marmorata Roezl, USANDO COLCHICINA COMO ESTRATEGIA DE MEJORAMIENTO GENÉTICO

<p><strong>Background:</strong> In Mexico, agaves are of economic and cultural importance. The "Agave Tepeztate" (<em>Agave marmorata</em> Roezl), is a species that unfortunately its unregulated use makes it susceptible to extinction. Consequently, different methods of efficient genetic improvement and propagation for its conservation have been sought, for example, the artificial induction of polyploids as this process can increase genetic diversity, improve adaptability, and for the possible generation of individuals resistant to diseases or adverse environmental conditions.<strong> Objective.</strong> To evaluate the effect of colchicine as a mitostatic agent and promoter of ploidy variation in plants of <em>Agave marmorata</em> Roezl. <strong>Methodology.</strong> In the present study, 1000 seeds of <em>A. marmorata</em> were germinated <em>in vitro</em> to obtain the seedlings to be used, which were subjected to treatments with three exposure times (16, 24 and 48 h) and concentrations of colchicine Sigma-Aldrich (0.05, 0.10 and 0.15 % (w/v)). <strong>Results.</strong> As a result of the investigation, it was observed that polyploidization was possible by applying a concentration of 0. 15 % of colchicine, with an immersion time of 24 h. At this concentration and immersion time the highest percentage of survival was obtained (60 %), in addition, a greater response was observed with respect to the number of regenerated shoots. Once the plants regenerated the root zone, the final chromosome count was carried out obtaining 120 chromosomes, which means that these plants are tetraploid (4<em>x</em>=4<em>n</em>=120). <strong>Implications. </strong>The chromosomal doubling of diploid to tetraploid individuals can generate positive changes in morphological characteristics, from the generation of larger organs, which can lead to a shortening of harvesting time and a greater amount of sugars produced in the stem due to the increased photosynthetic capacity derived from obtaining larger stalks.<strong> Conclusion</strong>. The effect of colchicine as a mitostatic agent for the induction of tetraploids of <em>A. marmorata</em> was effective; however, the time of exposure to the agent and its concentration is a fundamental factor for polyploidization.</p>