Enhancing in vitro growth and development of Dalbergia nigra shoots using microporous membranes: impacts on gas exchange, protein profile, ethylene, and polyamine levels

The use of lids with microporous membranes can enhance in vitro plant growth by promoting gas exchange, including ethylene exchange. We aimed to evaluate the influence of the microporous membrane, explant type, and culture medium on the in vitro development of Dalbergia nigra shoots, as well as on the protein profile, polyamines (PAs), ethylene and CO₂ levels. A total of 465 proteins were identified, of which 148 were differentially accumulated proteins, being 73 proteins up- and 75 down-accumulated in shoots grown in sealed-lid culture flasks containing microporous membranes compared to those grown without. The use of microporous membranes plays an important role in the accumulation of proteins related to photosynthetic activity process, such as ruBisCO_large domain-containing protein; ribulose bisphosphate carboxylase small chain; ribulose bisphosphate carboxylase small chain protein; and chlorophyll a-b binding protein, chloroplastic. Conversely, the decreased accumulation of proteins associated with amino acid synthesis linked to ethylene biosynthesis, such as aspartate aminotransferase, in shoots grown with microporous membranes was related to the lower level of ethylene than in shoots grown without membranes. The microporous membrane promoted an increase in total free PAs and putrescine contents in shoots, while higher CO₂ levels were detected in shoots grown without a microporous membrane. This is the first study showing the effects of promoting gas exchange on shoot development in D. nigra, in addition to exploring the interaction of protein accumulation with ethylene. This research can improve the understanding of propagation systems in D. nigra, an endangered species.