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• Optimizing disinfection protocols for yam explant regeneration in plant tissue culture

  66-72.

  Omotayo Komolafe

  Oyindamola H. Oyinloye

  Ejeoghene R. Ogbimi

  Kasali. O. Hassan

  Olugboyega S. Pelemo

  Views:

  469

  Yam (Dioscorea species), does not produce commercially viable seeds, and asexual propagation is faced with challenges resulting from carried-over infections from previous generations. Contamination is a prevalent problem in Plant Tissue Culture (PTC), making the development of cost-effective and efficient disinfection protocols crucial for successful PTC. This study aimed to evaluate the effectiveness of yam explant disinfection protocols using various immersion timings, disinfectant concentrations (including ethanol (C₂H₅OH), sodium hypochlorite (NaOCl), and hydrogen peroxide (H₂O₂)), and in single or combined disinfectants application. Twenty treatment combinations and one control were assessed on yam vines for Disinfection Efficiency (DE%), Negative Disinfection Effect (NDE%), and the regeneration of shoots and roots (SN & RN) from the culture after 21 days. The study showed that varying immersion times did not significantly impact the evaluated parameters. However, different concentrations of disinfectants resulted in diverse NDE responses. Surprisingly, higher concentrations of NaOCl led to reduced NDE, whereas lower concentrations increased NDE. On the contrary, higher concentrations of H₂O₂ increased NDE, while lower concentrations decreased it. Shoot and root regeneration rates were also significantly impacted by the choice of disinfection protocol. The research concluded that dual disinfection protocol, specifically 70% ethanol for 7 minutes followed by NaOCl, was most effective for eliminating surface-borne contaminants and achieving successful in vitro propagation of yam plantlets. This method offers a cost-effective solution for establishing microbe-free tissue culture yam plantlets and provides a basis for future research on other Dioscorea plants.

• Micropropagation of Rudbeckia hirta L. from seedling explants

  105-108

  P. Szarvas

  A. Zsila-André

  Z. Kováts

  M. G. Fári

  Views:

  320

  We conducted experiments for developing an in vitro micropropagation protocol starting from meristems of Rudbeckia hirta L seedlings. We pre-soaked the seeds in sterile ion-exchanged water for 17 hours, and then achieved surface disinfection in two separate steps. First, we used concentrated household sodium-hypochloride solution for 20 minutes and, also for 20 minutes, we applied hydrogen peroxide of 10%, which was followed by washing with sterile ion-exchanged water three times. For the propagation of seedling meristems, the combination of half-strenght solid Murashige and Skoog (1962) culture medium containing 10 mg/1 of kinetin or 2 mg/I of kinetin + 0.1 mg/1 of 2iP proved to be the most suitable. The average number of shoot-buds developed from the seedling axillary meristem in the best culture media varied between 5 and 17. Without separating them, we inoculated the shoot-bud clusters on MS culture medium containing 2 mg/1 of IAA. After four weeks of incubation we obtained elongated shoots which we separated and inoculated into a new culture medium and we obtained elongated roots. The rooted plants were gradually acclimatised in the cultivation room, potted and carried to a greenhouse, and then planted in open field for subsequent observation. By adopting this method, our laboratory started the micropropagation of the superior and/or elite genotypes of the Rudbeckia hirta L. being of special value in respect of breeding.