Characterization of Nitrogen Use by Neotropical Myrtaceae in Dry and Wet Forests of Southeast Brazil

• Published in: Earth (Basel, Switzerland) Switzerland), 2022-12, Vol.3 (4), p.1290-1304
• Main Authors: Pereira-Silva, Erico Fernando Lopes, Joly, Carlos, Sodek, Ladaslav, Hardt, Elisa, Aidar, Marcos
• Format: Article
• Language: English
• Subjects: Amino acids; Citrulline; Dry season; Environmental factors; Flowers & plants; Forests; Glutamine; Leaves; Metabolism; Metabolites; Myrtaceae; Nitrate reductase; nitrate reductase activity; Nitrates; Nitrogen; NO3− responsiveness; Nutrients; Ombrophylous Dense Forest; Phosphorus; Physiology; Plant nutrition; Plant species; Preferences; Rainy season; Reductases; Savanna Woodland; Seasonal variations; semideciduous forest; tree species; Trees; Tropical environments; Tropical soils; Xylem
• ISSN: 2673-4834; 2673-4834
• DOI: 10.3390/earth3040073

We hypothesized that neotropical Myrtaceae could be organized into groups that are naturally less or non-responsive to NO3−, and that use other N forms, such as amino acids, for internal N transport. Ecophysiological tests were conducted to measure nitrate reductase activity (NRA), NO3− content, total N, δ15N natural abundance, the C:N ratio in leaves, free amino acid, and NO3− transport via xylem sap. We showed that Myrtaceae tree species have a relatively low NRA, in addition to little NO3− in leaves and free NO3− in the xylem sap during the wet and dry seasons. We suggested a possible compartmentalization of N use, wherein plants derive their internal N from and use their transport mechanism to move N between below-ground and above-ground parts, assimilating and transporting more N and C through amino acids such as glutamine, arginine, and citrulline. Evidence of low NO3− availability in tropical soils is important when trying to understand forest species’ N-use strategies, given their importance to plant nutrition. Differences in the responses of some Myrtaceae species to the seasonality of environmental factors suggest the need for further studies concerning N in natural forests, for example, to help understand the problem of N deposition ecosystems.