Establecimiento de un sistema de selección in vitro de variedades venezolanas de arroz (Oryza sativa L.) resistentes al hongo pyricularia grisea

Abstract

Rice after wheat is the most important cereal in the world, however, it is susceptible to attack by many pathogens, which Pyricularia grisea being the most harmful. In the current study we established an in-vitro selection system of P. grisea on Venezuelan rice varieties. A somatic embryogenesis regeneration system was optimized (induction, regeneration and desiccation) to expose embryogenic callus (E) to crude filtrate “CF” selection pressure through changes at the same concentration “SC” or progressive concentration increments “ PIC “of P. grisea, and thus obtain plants tolerant to the pathogen. The maximum percentage of embryogenic callus induction ranged between 30-65% in the four varieties (Araure-4 and Venezuela- 21: 1 mg.L-1 + 2 mg.L-1 K; Cimarron: 3 mg.L-1 mg.L-1 + 2 K; Centauro: 1 mg.L-1 + 2 mg.L-1 BAP) while regeneration was between 44 and 52% with 0.5 mg.L-1 + 2 mg.L- 1 BAP 48 h of desiccation for Centauro and 24 h for the other three varieties. The regeneration frequency of embryogenic callus decreased as the concentration of FC increased, regardless of the method of selective pressure. The average differentiated plants per variety, depended on the pressure method used, with the PIC system being the most favorable (25% for Centauro and 50% for the other three varieties). The result demonstrated, to resistance expressed for plants in vivo does not correspond to the in vitro conditions.