Disturbance in the allocation of carbohydrates to regenerative organs in transgenic Nicotiana tabacum L

• Published in: Journal of experimental botany Vol. 51; no. 342; pp. 115 - 122
• Main Authors: Sheveleva, Elena V., Jensen, Richard G., Bohnert, Hans J.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Oxford University Press 01.01.2000; OXFORD UNIVERSITY PRESS; Oxford Publishing Limited (England)
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Carbohydrate Metabolism; d‐ononitol; Flower buds; Flowers; Fundamental and applied biological sciences. Psychology; g fw; Genetic engineering applications; Genetics and breeding of economic plants; gram fresh weight; IMT1; Ions; Leaves; mannitol; Meristems; Molecular Physiology: Engineering crops for hostile environments; myo‐inositol O‐methyltransferase; Nicotiana - metabolism; Phenotype; Phenotypes; Phloem; Plant breeding: fundamental aspects and methodology; Plant growth; Plants; Plants, Genetically Modified - metabolism; Plants, Toxic; seed production; source–sink disturbance; Stems; Transgenic plants; transgenic tobacco; Flower; Enzyme; Seed production; Transferases; Mannitol-1-phosphate 5-dehydrogenase; Gene expression; Nicotiana tabacum; Source sink relationship; Methyltransferases; myo-Inositol 3-O-methyltransferase; Dicotyledones; Angiospermae; Mannitol; Development; Spermatophyta; Transgenic plant; Oxidoreductases; Polyol; Solanaceae; Experimental plant; Biological accumulation
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jexbot/51.342.115

Transgenic tobacco (Nicotiana tabacum L, cv. SR‐1) expressing mannitol 1‐phosphate dehydrogenase, MTLD, in chloroplasts and myo‐inositol O‐methyltransferase, IMT1, in the cytosol after crossing of lines which expressed these foreign genes separately has been analysed. Plants expressing both enzymes accumulated mannitol and 𝒟‐ononitol in amounts comparable to those following single gene transfer and showed phenotypically normal growth during the vegetative stage. Induction of flowering for transgenovar and wild‐type occurred at the same time, but during flowering the phenotype of the transformed plants changed. Compared to wild‐type, transgenic plants were characterized by curled, smaller upper leaves and elongated stems during flowering; incomplete development of flower buds with shorter sepals and pedicels resulted in increased abortion. Flowers completing development were normal. The vegetative biomass of the transformed plants was slightly higher than that of wild‐type. Concentrations of soluble sugars and potassium were lower than in wild‐type only in the apical parts of the transgenic plants. Both enzymes, under control of the CaMV 35S promoter, promoted accumulation of mannitol and 𝒟‐ononitol in the youngest leaves close to the vegetative meristem and in flowers, suggesting that their presence could signal lower sink demand leading to a decrease in carbon import to flowers and developing seed capsules. The interpretation here is that increases of inert carbohydrates in developing sinks interfere with metabolism, such as respiration or glycolysis. This interference may be less significant in source tissues during vegetative growth than in sink tissues during seed development.