Enriquecimento com CO₂ no cultivo "in vitro" fotoautotrófico de abacaxis ‘Pérola’ e ‘Turipaz’: impactos na aclimatização, na anatomia e na fotossíntese

Abstract

In vitro micropropagation is a widely used strategy for clonal plant multiplication; however, conventional culture systems impose physiological constraints associated with the artificial microenvironment, which limit carbon assimilation and delay the acquisition of autotrophy. In this context, CO􁁷 enrichment emerges as a promising approach to mitigate these limitations by inducing metabolic, anatomical, and functional adjustments in plants. Accordingly, the objective of this study was to evaluate the effects of CO􁁷 enrichment during photoautotrophic in vitro culture on growth, carbon-related attributes, and leaf micromorphometric traits of Ananas comosus cultivars ‘Pérola’ and ‘Turipaz’, as well as to assess how these responses are expressed during ex vitro acclimatization. The experiment was conducted in a completely randomized design in a 2 × 2 factorial arrangement, combining two cultivars (‘Pérola’ and ‘Turipaz’) and two [CO􁁷], aCO􁁷 420 ± 30 μmol mol⁻¹) and eCO􁁷 (800 ± 30 μmol mol⁻¹), for 50 days of in vitro culture, followed by 50 days of ex vitro acclimatization. CO􁁷 enrichment significantly increased shoot and root length, leaf number, rosette diameter, leaf area, and shoot fresh and dry biomass in both cultivars, while specific leaf mass was not affected. Root biomass exhibited a genotype-dependent response, with higher values in ‘Turipaz’ under aCO􁁷, whereas eCO􁁷 increased root fresh biomass only in ‘Pérola’, with no effect on root dry biomass. CO􁁷 enrichment increased chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid contents in both cultivars, with consistently higher total chlorophyll values in ‘Turipaz’. Photosynthetic performance was enhanced under eCO􁁷, as indicated by increases in net CO􁁷 A, gs, Ci, Ci/Ca, and PI, without changes in A/Ci or A/gs. TSC content increased markedly under eCO􁁷, with higher values in ‘Pérola’ at both [CO􁁷]. CO􁁷 enrichment promoted leaf anatomical modifications, including increased thickness of the epidermal layers, aquifer parenchyma, chlorophyll parenchyma, and vascular bundles, with tissue- and genotype-dependent responses under aCO􁁷 that were attenuated under eCO􁁷. During ex vitro acclimatization, plants derived from eCO􁁷-grown cultures maintained greater growth, biomass accumulation, pigment contents, total soluble carbohydrates, and part of the evaluated anatomical traits, with overall greater vigor observed in the cultivar ‘Turipaz’. In conclusion, CO􁁷 acts as a key variable in photoautotrophic in vitro micropropagation systems for pineapple by modulating plant morphophysiological trajectories during in vitro culture and positively conditioning plant performance during ex vitro acclimatization, reinforcing the importance of integrated approaches that consider functional continuity between these two phases of the propagation process