Evaluation of the effect of nitrous oxide on the ploidy level of Eustoma grandiflorum

Lisianthus (Eustoma grandiflorum) is an ornamental species that has gained relevance in the last decade. Originally from northern Mexico and the southern United States, it is a new floral crop that has become one of the main cut flowers and in which larger flowers are wanted. Polyploidization consists of doubling the chromosome number of a species and this can result in obtaining larger plants. It exists naturally, but can be induced by chemical agents as colchicine, however, the success rate is low. Nitrous oxide, a gas, acts in a similar way to colchicine and has been used for the induction of 2n gametes, but not in somatic cells. The objective of this work is to know the effect of nitrous oxide, applied under different exposure times and pressures, on the ploidy level of Eustoma grandiflorum. Seeds of E. grandiflorum were disinfected and germinated in ½MS medium. Once the cotyledons emerged, they were treated at 5 and 6 atm in a pressure chamber for 24, 48, and 72 h, with 50 seedlings per treatment. Also, colchicine treatments were carried out, subjecting 50 seeds per treatment to 0.1 and 0.2% during 2, 4 and 6 h. The treated seedlings were transferred to ½MS medium including benzyl adenine (BA) and gibberellic acid (GA₃) for their growth. Subsequently, they were transferred to ½MS medium with casein hydrolysate and indole-3-butyric acid (IBA) to induce roots. The survival rate, the size of the plants and the relative DNA content were recorded. After the treatments, the highest survival and mortality in the N₂O treatments were 6 atm at 72 h and 5 atm at 72 h, respectively, while in the colchicine treatments, they were 0.1% for 2 h and 0.2% for 6 h. The size of the plants obtained was measured and, among them there were approximately 190 plants with sizes that double or triple the size of the control plants. Currently, there are approximately 3000 multiplied plants and DNA relative content analyzes show the presence of polyploid plants in the N₂O treatments, chromosome counts have yet to be performed.