Mineral nutrient supply, cell wall adjustment and the control of leaf growth

• Published in: Plant, cell and environment Vol. 20; no. 2; pp. 239 - 246
• Main Authors: SNIR, N., NEUMANN, P. M.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-02-1997; Blackwell
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; cell size; cell wall plasticity; Chemical agents; Economic plant physiology; Fundamental and applied biological sciences. Psychology; leaf growth; Mineral nutrition; Nutrition. Photosynthesis. Respiration. Metabolism; osmotic potential; Plant physiology and development; Vegetative apparatus, growth and morphogenesis. Senescence; Zea mays L; Monocotyledones; Zea mays; Nutrition; Growth; Deficiency; Plant leaf; Inorganic element; Cereal crop; Cell wall; Gramineae; Hydroponic cultivation; Angiospermae; Plasticity; Development; Spermatophyta
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1046/j.1365-3040.1997.d01-57.x

ABSTRACT
The possibility that changes in the plasticity of expanding cell walls are involved in regulating early leaf growth responses to nutrient deficiencies in monocot plants was investigated. Intact maize seedlings (Zea mays L.) which were hydroponically grown with their roots in low‐nutrient solution (1 mol m−3 CaCl2) showed early inhibition of first‐leaf growth, as compared with seedlings on complete nutrient solution. This early inhibition of leaf growth was not associated with reduced cell production. However, segmental elongation along the cell expansion zone at the base of the leaf and the lengths of mature epidermal cells were reduced by the low‐nutrient treatment. Solute (osmotic) potentials in the expanding leaf tissues were unchanged. In contrast, low‐nutrient treatments significantly altered leaf plasticity, i.e. the irreversible extension caused by applying a small force in the direction of leaf growth. For example, in vivo plasticity decreased, along with leaf growth, after transfer of seedlings from complete nutrient solution to low‐nutrient solution for 15 h. Conversely, in vivo plasticity increased, along with leaf growth, after transfer of plants previously grown on low‐nutrient solution to complete nutrient solution for 15 h. The nutrient treatments also induced similar changes in the in vitro plasticity of the expanding leaf cell walls. There were no consistent changes in elasticity. Thus, reductions in the plasticity of expanding leaf cell walls appear to be involved in controlling the early inhibition of maize leaf growth by root imposition of nutrient stress.