Sensitivity of Seeds to Chemical Mutagens, Detection of DNA Polymorphisms and Agro-Metrical Traits in M1 Generation of Coffee (Coffea arabica L.)

Coffee (Coffea Arabica L.) is threatened by biotic and abiotic stresses. Nevertheless, the breeding of Arabica coffee is restricted due to its low genetic diversity. Crop improvement via mutagenesis represents an alternative for increasing genetic variability and facilitating breeding. In this sense, coffee seeds cv. Catuaí were treated for 8 h with a solution of sodium azide (NaN₃) (0, 50, 75, 100, and 125 mM) and ethyl methane sulfonate (EMS) (0, 80, 160, 240, 320, and 400 mM). The genetic variability induced in coffee plants after mutagenic treatment with sodium azide was determined by RAPD and AFLP analyses. As the concentration of applied NaN₃ and EMS increased, the germination, seedling height, and root length decreased. The LD₅₀ values for NaN₃ and EMS were between 50-75 mM and 160-240 mM, respectively. For the 12 RAPD primers evaluated, a total of 46 fragments were obtained of which 34 were polymorphic bands (74%). The amplification with six AFLP selective primer combinations allowed the identification of 36 polymorphisms (17.8%). The analysis revealed that both NaN₃ and EMS induced variability within the DNA regions amplified with AFLP and RAPD markers. Finally, under field conditions, significant differences were noticed with respect to plant height, number of nodes in the orthotropic stem, and number of branches of the M1 mutant (NaN₃-treated) plants compared to the non-mutant plants. Optimal conditions for NaN₃ and EMS mutagenesis using seeds were determined and the optimized conditions have been used to generate a NaN₃ mutant M1 coffee var. Catuaí population.