Phosphoenolpyruvate carboxykinase plays a role in interactions of carbon and nitrogen metabolism during grape seed development

• Published in: Planta 1999-11, Vol.210 (1), p.9-18
• Main Authors: Walker, R.P, Chen, Z.H, Tecsi, L.I, Famiani, F, Lea, P.J, Leegood, R.C
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Antiserum; asparagine; Biological and medical sciences; carbohydrate metabolism; carbon; Economic plant physiology; endosperm; enzyme activity; Enzymes; Flowering; Fundamental and applied biological sciences. Psychology; immunohistochemistry; Integument; Net assimilation, photosynthesis, carbon metabolism. Photorespiration, respiration, fermentation (anoxia, hypoxia); nitrogen; nitrogen metabolism; Nutrition. Photosynthesis. Respiration. Metabolism; Phloem; phosphoenolpyruvate carboxykinase; Plant cells; plant tissues; plant vascular system; Plants; Seed development; Seeds; Testa; Vitis vinifera
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s004250050648

Phosphoenolpyruvate carboxykinase (PEPCK) was shown to be present in a range of developing seeds by measurement of its activity and by immunoblotting. Its function was investigated during grape (Vitis vinifera L.) seed development. The maximum abundance of PEPCK coincided with the deposition of storage reserves. At this stage of development, immunohistochemistry showed that PEPCK was very abundant in a layer of cells located at the boundary of developing storage tissues and in the chalaza (close to the termination of the vascular supply to the seed) and was also present in the palisade layer of the seed coat (the inner layer of the outer integument). Earlier in development PEPCK was also present in the developing palisade layer and in the inner region of the nucellus which surrounds the developing endosperm. At later stages of development, PEPCK was located in the outer region of the endosperm. However, PEPCK was present in the phloem of the seed at all stages of development. Feeding of asparagine to developing grape seeds led to a strong induction of PEPCK. We suggest that, in developing grape seeds, both the chalaza and palisade tissue may distribute imported assimilates from the vasculature to the developing storage tissues and that PEPCK may play a role in the metabolism of nitrogenous assimilates during their delivery from the vasculature to the storage tissues.