Carbohydrate and dehydrin-like protein profiles during Araucaria angustifolia seed development provides insights toward ex situ conservation

Authors: GROETEN, DANIELA - University Of Santa Catarina; FARIAS-SOARES, FRANCINE - University Of Santa Catarina; ROGGE-RENNER, GLADYS - University Of Santa Catarina; PEREIRA, MARIA - University Of Santa Catarina; Walters, Christina; SILVEIRA, VANILDO - University Of Santa Catarina; CATARINA, CLAUDETE - University Of Santa Catarina; GUERRA, MIGUEL - University Of Santa Catarina; STEINER, NEUSA - University Of Santa Catarina

Submitted to: Trees
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/14/2023
Publication Date: 6/3/2023
Citation: Groeten, D., Farias-Soares, F., Rogge-Renner, G.D., Pereira, M.L., Walters, C.T., Silveira, V., Catarina, C.S., Guerra, M.P., Steiner, N. 2023. Carbohydrate and dehydrin-like protein profiles during Araucaria angustifolia seed development provides insights toward ex situ conservation. Trees. https://doi.org/10.1007/s00468-023-02419-z.
DOI: https://doi.org/10.1007/s00468-023-02419-z

Interpretive Summary: So-called recalcitrant seeds do not survive drying and are therefore more difficult to process for cryopreservation. Plants producing these types of seeds often grow in tropical forests. The ability to tolerate drying is acquired during the embryogenic program of seeds. This paper examines the accumulation of metabolites commonly thought to protect cytoplasm during drying in embryos of Araucaria angustifolia (Brazilian pine). Putative protectants did accumulate during the late maturation phases of this species, but in lower quantities than is typical for a desiccation tolerant seed. Therefore, cryopreserving this species will require different strategies that typically involve in vitro techniques such as working with somatic embryos or protecting immature embryos with exogenous protectants such as Plant Vitrification Solutions(PVS)Embryos in early-to-late embryo transition stage might be potentially able to respond the dehydration and cryopreservation process and in addition to producing somatic embryos.

Technical Abstract: Araucaria angustifolia (Bert. O. Kuntze) is a threatened and endemic species and takes almost 24 months after pollination (MAP) for seed maturation. Mature seeds lose viability if dried and do not survive prolonged storage which seems to be aconsequence of metabolic profile. To understand how maturation occurs, we examined the biochemical changes within developing seeds. Carbohydrate and total protein contents as well as appearance of dehydrin-like proteins, were analyzed duringthe proembryogenic (15–6 MAP), early embryogenesis (17–18 MAP) and late embryogenesis (19–23 MAP) stages. Three embryos stages were described in A. angustifolia seed development. Intense mitotic activity occurs during pro-embryogenic and early embryogenesis stages, which are also characterized by high fructose and glucose and low sucrose contents. During early embryogenesis, embryos had low total and heat-soluble protein contents and dehydrin-like proteins were not present. Interestingly, during late embryogenesis the sucrose to hexose ratio increased markedly and four fractions of dehydrin-like proteins with molecular masses near 21.5, 23, 26 and 27 kDa were detected. Our results show a high diversity of dehydrin-like proteins and carbohydrates over embryo development, which are not necessarily associated with desiccation tolerance. This may explain the recalcitrant seed behavior observed in Araucaria seeds and may interfere with successful cryopreservation of this important species. Due to the size of the mature embryo, cryopreservation efforts are based on using embryos in the early-to-late embryo transition stage and somatic embryogenesis might be improved by sucrose addition at maturation media.