Abstract
Somatic embryogenesis (SE) is a laboratory-based method that allows for cost-effective production of large numbers of clonal copies of plants, of particular interest for conifers where other clonal propagation methods are mostly unavailable. In this study, the effect of l-glutamine as an organic nitrogen source was evaluated for three contrasted media (containing NH4 + NO3 without glutamine, or glutamine + NO3, or glutamine without inorganic nitrogen) during proliferation and maturation of Norway spruce somatic embryos through analyses of activities of the key enzymes of nitrogen metabolism: nitrate reductase (NR), glutamine synthetase (GS) and arginase. A major change in nitrogen metabolism was indicated by the increased activity of GS from zero in the proliferation stage through maturation to high activity in somatic embryo-derived plantlets; furthermore, NR activity increased from zero at the proliferation stage to high activity in maturing embryos and somatic-embryo derived plantlets. In contrast, arginase activity was high at all stages. In accordance with the GS and NR data, proliferation was fastest on the glutamine media, the largest number of mature embryos developed on the glutamine medium without inorganic nitrogen, and the ammonium content of proliferating cultures was much higher than that of mature somatic embryos. The best developed embryos, judged by germination, were from the glutamine + NO3 medium. These insights into nitrogen utilization will help to improve culture medium composition.
Highlights
Norway spruce (Picea abies (L.) H.Karst.) is a key species for forest production in the NorthernHemisphere, including Sweden [1]
proembryogenic masses (PEMs) do not proliferate on media lacking organic nitrogen
It was demonstrated that the reduced growth of PEMs on medium containing only NH4 + NO3, as compared to medium supplemented with L-glutamine (Gln; Gln + NO3 media), was associated with absence of detectable glutamine synthetase (GS) and nitrate reductase (NR) activities
Summary
Norway spruce (Picea abies (L.) H.Karst.) is a key species for forest production in the NorthernHemisphere, including Sweden [1]. To meet the increased demand for wood products, propagation of superior trees from breeding programs is necessary [1,2]. This has usually required seed orchards, which are expensive and have problems with both pollen contamination and cone diseases [3], or clonal propagation by cuttings, which to date has had only limited success [1]. Conifers are able to take up both inorganic (nitrate, ammonia) and organic nitrogen sources (L-glutamine, L-arginine) [4,5]. Depending on which nitrogen form is supplied, the uptake preferences
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
