Amino acid utilization in seeds of loblolly pine during germination and early seedling growth. I. Arginine and arginase activity

• Published in: Plant physiology (Bethesda) 1997-04, Vol.113 (4), p.1125-1135
• Main Authors: King, J.E. (University of Alberta, Edmonton, Alberta, Canada.), Gifford, D.J
• Format: Article
• Language: English
• Subjects: ACIDE AMINE; ACTIVIDAD ENZIMATICA; ACTIVITE ENZYMATIQUE; Agronomy. Soil science and plant productions; AMINO ACIDS; AMINOACIDOS; ANALISIS CUANTITATIVO; ANALYSE QUANTITATIVE; ARGINASA; ARGINASE; ARGININA; ARGININE; Biochemistry and Enzymology; Biological and medical sciences; Cotyledons; CRECIMIENTO; CROISSANCE; DEGRADACION; DEGRADATION; DEVELOPMENTAL STAGES; Economic plant physiology; Embryo development. Germination; Embryos; ENZYMIC ACTIVITY; ETAPAS DE DESARROLLO; FREE AMINO ACIDS; Fundamental and applied biological sciences. Psychology; GERMINACION; GERMINATION; Germination and dormancy; GRAINE; GROWTH; Growth and development; Imbibition; METABOLISM; METABOLISME; METABOLISMO; METABOLITE; METABOLITES; METABOLITOS; Pine trees; PINUS TAEDA; Plant physiology and development; PLANTULAS; PLANTULE; PROTEINAS; PROTEINE; PROTEINS; QUANTITATIVE ANALYSIS; Seedling culture; Seedling growth; SEEDLINGS; SEEDS; SEMILLA; STADE DE DEVELOPPEMENT; Storage proteins
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.113.4.1125

The mobilization and utilization of the major storage proteins in loblolly pine (Pinus taeda L.) seeds following imbibition were investigated. Most of the seed protein reserves were contained within the megagametophyte. Breakdown of these proteins occurred primarily following radicle emergence and correlated with a substantial increase in the free amino acid pool in the seedling; the majority of this increase appeared to be the result of export from the megagametophyte. The megagametophyte was able to break down storage proteins and export free amino acids in the absence of the seedling. Arginine (Arg) was the most abundant amino acid among the principal storage proteins of the megagametophyte and was a major component of the free amino acid pools in both the seedling and the megagametophyte. The increase in free Arg coincided with a marked increase in arginase activity, mainly localized within the cotyledons and epicotyl of the seedling. Arginase activity was negligible in isolated seedlings. Experiments with phenylphosphorodiamidate, a urease inhibitor, supported the hypothesis that arginase participates in Arg metabolism in the seedling. The results of this study indicate that Arg could play an important role in the nutrition of loblolly pine during early seedling growth