Spectral quality and temporary immersion bioreactor for in vitro multiplication of Eucalytpus grandis × Eucalyptus urophylla

Abstract

Spectral quality is an important factor for in vitro development of explants in a bioreactor system. Based on the need to optimize micropropagation for E. grandis × E. urophylla clones, the aim of the study was to assess the spectral quality of in vitro multiplication in temporary immersion bioreactor (TIB). The tissue used to generate the explants (i.e., the nodal segment with 1 cm of length and two axillary bud without leaves) was previously in vitro established and multiplied, it derived from ministumps of E. grandis × E. urophylla clone grown in a semi-hydroponic system. The spectral quality of in vitro multiplication was assessed through five light sources (i.e., fluorescent lamp, red, green, blue, and yellow cellophane). Morphological and anatomical features of tissues grown in TIB were evaluated at 90 days. Based on the results, yellow and blue spectral qualities were the most suitable to be adopted for in vitro multiplication of E. grandis × E. urophylla, since they enabled lesser hyperhydricity, favors high number of shoots per explant and shoot length, as well as thicker mesophyll and spongy parenchyma; arise as an alternative for large-scale production of eucalypts clonal plants.

Spectral quality influence on in vitro morphophysiological responses of Eucalyptus dunnii Maiden and Eucalyptus grandis W.Hill ex Maiden × E. urophylla S.T.Blake

“…Many studies have shown the superiority of white light sources for in vitro plant development (Batista et al 2018;Abiri et al 2020), although responses vary. Genotypic differences in the in vitro development have also been reported in different clones of Eucalyptus, such as Eucalyptus grandis × E. urophylla (Souza et al 2020a;Miranda et al 2020), Eucalyptus benthamii (Brondani et al 2018), and Eucalyptus globulus (Oliveira et al 2016). Thus, different results are observed for explants in the in vitro multiplication stage, the response varying according to the genotype and the culture conditions (e.g., spectral quality).…”

“…Spectral qualities red, blue, yellow, purple and green were provided, under all growth stages, by filtering the light output of the fluorescent light bulbs through double sheets of cellophane (Souza et al 2020a) replaced every cycle. The light spectra were measured using a SPECTRA PEN Z850 portable spectrophotometer (Qubit Systems, Kingston, Ontario, USA).…”

“…Activation is dependent on genetic and epigenetic factors intrinsic to the species, as well as on their interaction for phenotypic expression (Gilmartin et al, 1990;He et al 2011), however, this activation begins with the stimulation of photoreceptors that signal metabolic pathways causing direct effects on tissue cell division and differentiation (Gilmartin et al 1990). Studies of different light spectra on the in vitro propagation of eucalypts species, provide important information to large-scale production of clones with high phytosanitary quality and high vigor (Souza et al 2020a;Souza et al 2020b).…”

“…Eucalypt micropropagation under different light qualities has been extensively studied showing positive results in plant health, inducing the increase of shoots and leaves (Souza et al 2020a;Miranda et al 2020), as well as seed germination (Rokich & Bell 1995). Besides, the use of cellophane plastic has shown to be a low-cost viable alternative as a filter for incident fluorescent light and providing the desired wavelength in micropropagation protocols (Souza et al 2020b).…”

Temporary Immersion System for Production of Biomass and Bioactive Compounds from Medicinal Plants

“…An immersion frequency of 30 s every 30 min or every 3 h produced the highest number of shoots per explant in Jeffersonia dubia [78] and in Eucalyptus grandis × E. urophylla ( [70] (Table 1). The effect of immersion interval (15 min immersion every 4 h) was more critical in Aquilaria malaccensis shoot cultivation when an increase in the number of shoot regeneration (5.12) and biomass (3.12 g) were obtained compared to 5 min/4 h [48].…”