Optimization of Nitrogen Source to Improve Loblolly Pine Organogenesis by Using CHAID Data Mining Algorithm

BARONE, J.; LUNA, C.; OBERSCHELP, J; SANSBERRO, P

Dublin

Congreso; IAPB 2018; 2018

International Association for Plant Biotechnology

The in vitro bud differentiation is markedly influenced by the availability and form of nitrogenous source. To analyze the regeneration of adventitious buds in loblolly pine (Pinus taeda), the Chi-Squared Automatic Interaction Detection (CHAID) data mining algorithm was used to analyze the regeneration rate, number of adventitious buds regenerated per explant, oxidation, and callus proliferation from mature zygotic embryos. The explants were cultured on Murashige and Skoog (1962) semisolid (agar 6.5 g·L-1) medium reduced to half strength and supplemented with different nitrogen concentrations (5, 10, 20 and 30 mM) and nitrate: ammonium rates (0.5, 1, 2 and 3). Sucrose (30 g·L-1), thidiazuron (0.1 mg·L-1), and 6-benzylaminopurine (0.1 mg·L-1) were added in all cases. A completely randomized experimental design with five repetitions and an experimental unit of ten explants was used. The cultures were incubated under light (116 µmol·m-2·s-1, 14 h photoperiod) and temperature (27±2 °C) controlled conditions for 35 days. The results were statistically analyzed by CHAID analysis. The significance level for splitting nodes and merging categories was 0.01. Both, NO3-/NH4+ rate and total nitrogen concentration (TN) affected the morphogenic process. The highest regeneration rate (93.3±7.2%) was observed when the basal medium was supplemented with a NO3-/NH4+ ratio greater than 0.5 and TN ranged from 5 to 10 mM. Whereas, the number of adventitious buds regenerated per explants was highest (16.1±4.1) when the NO3-/NH4+ varied between 0.5-2 and TN higher than 5 mM. Independently of the NO3-/NH4+ratio, the oxidation rate increased (22.6±13.3%) when TN was higher than 20 mM. Callus proliferation was highest (63.8±18.1%) with a NO3-/NH4+ ratio of 0.5 and TN higher than 5 mM. These findings suggest that an optimal culture medium for loblolly pine bud regeneration it should contain a NO3-/NH4+ ratio between 0.5-2, and a total nitrogen content ranged from 5 to 10 mM.