Abstract
Background
Cultivating threatened plant species is vital for conservation, safeguarding against extinction by ensuring propagation and maintaining genetic diversity. In this study, we conducted an integrative morphological, physiological, and quantitative proteomic analysis of Stephanopodium engleri plants grown under different substrates and nutritional sources. Stephanopodium engleri is an endangered and range-restricted species endemic to the Quadrilátero Ferrífero region, a historical hub for mining activities in Brazil. Seedlings of S. engleri were cultivated in three different substrates: organic substrate (Carolina Soil® - CS), dystrophic soil (DS), and a mixture of both substrates (1:1). Additionally, we evaluated nutrient availability levels, including complete fertilization and half of the nutrients in the DS, as well as treatments with complete fertilization excluding nitrogen (N), phosphorus (P), potassium (K), and micronutrients.
Results
Different nutritional sources resulted in changes in the growth of S. engleri, with nitrogen (N), phosphorus (P), and micronutrients identified as the most limiting nutrients. The species exhibited maximum growth with half of the applied fertilization, suggesting a low nutritional requirement. The highest growth was strongly related to nutritional availability, coupled with adjustments in the photosynthetic apparatus and protein regulation, with no significant differences in morpho-anatomical traits. The most representative proteins displayed a diverse array of metabolic functions, particularly related to iron (Fe) and zinc (Zn) homeostasis, participation in photosynthesis and energy pathways, reactive oxygen species (ROS) signaling, and the preservation of functional structures.
Conclusions
Our findings are crucial to support field planting, as adequate fertilization is essential to produce high-quality seedlings, thereby facilitating plans to reintroduce the species into its native environment. Additionally, our results reveal insights into S. engleri physiology and adaptations. Our data can further support management and conservation plans through the reinforcement of natural populations, introduction of new populations, maintenance of germplasm banks, and living collections.