Leaf expansion

Van Volkenburgh, E. Davies, W.J. (1983). Inhibition of light-stimulated leaf expansion by ABA. Journal of Experimental Botany, 345, 835-45. 

Thompson, A. J., J. Andrews et al. (2007). Overproduction of abscisic acid in tomato increases transpiration efficiency and root hydraulic conductivity and influences leaf expansion. Plant Physiol. 143(4) ... 

MacdowalP found that tobacco leaves were most susceptible to injury by ozone (at 0.035 ppm for 5 h) just after full leaf expansion. This point corresponded to the banning of the decline in protein content. Lee modified the nitn en content of tobacco leaves by supplying urea and found a positive correlation of injury caused by ozone (at 1 ppm for 5 h) with nonprotein nitrogen, but not with protein. This result is in contrast with that of Ting and Mukeiji, who found that, in cotton leaves (in which the period of maximal susceptibility was at about 75% of full leaf expansion), the amino acid pool was low at the time of maximal susceptibility. However, ozone treatment (0.7 ppm for 1 h) increased the free amino acid pool. 

Sullivan, J.H. et al.. Changes in leaf expansion and epidermal screening effectiveness in Liquid-ambar styraciflua and Pinus taeda in response to UV-B radiation. Physiol Plant., 98, 349, 1996. 

A somewhat similar constraint applies to the early development of sclerophylly, a potential herbivore deterring feature. Oonstructlon of rigid cell walls and the production of lignin and other compounds would certainly slow the overall rate of leaf expansion and prolong the period during which the leaf Is a net importer of carbon reserves. 

Deployment of defensive chemicals during leaf expansion. 

We propose that the patterns of polyphenol production In leaves are related to the duration of new leaf production. Species which acconpllsh leaf expansion and shoot extension within a short time period, especially In cold climates, should generally have low polyphenol concentrations In young leaves compared to species with extended periods of active growth. 

The phenolic acids of interest here [caffeic acid (3,4-dihydroxycinnamic acid), ferulic acid (4-hydroxy-3-methoxycinnamic acid), p-coumaric acid (p-hydroxycinnamic acid), protocatechuic acid (3,4-dihydroxybenzoic acid), sinapic acid (3,5-dimethoxy-4-hydroxyxinnamic acid), p-hydroxybenzoic acid, syringic acid (4-hydroxy-3,5-methoxybenzoic acid), and vanillic acid (4-hydroxy-3-methoxybenzoic acid)] (Fig. 3.1) all have been identified as potential allelopathic agents.8,32,34 The primary allelopathic effects of these phenolic acids on plant processes are phytotoxic (i.e., inhibitory) they reduce hydraulic conductivity and net nutrient uptake by roots.1 Reduced rates of photosynthesis and carbon allocation to roots, increased abscisic acid levels, and reduced rates of transpiration and leaf expansion appear to be secondary effects. Most of these effects, however, are readily reversible once phenolic acids have been depleted from the rhizosphere and rhizoplane.4,6 Finally, soil solution concentrations of... 

Since the actual or potential phytotoxicity of a phenolic acid is determined by its physical and chemical properties and the susceptibility of the plant process involved, the actual or potential phytotoxicity of a given phenolic acid is best determined in nutrient culture in the absence of soil processes. The phytotoxicity observed in soil systems represents a realized or observed phytotoxicity, not the actual phytotoxicity, of a given phenolic acid. For example, the actual relative phytotoxicities (or potencies) for cucumber seedling leaf expansion were 1 for ferulic acid, 0.86 for p-coumaric acid, 0.74 for vanillic acid, 0.68 for sinapic acid, 0.67 for syringic acid, 0.65 for caffeic acid, 0.5 for p-hydroxybenzoic acid and 0.35 for protocatechuic acid in a pH 5.8 nutrient culture.5 In Portsmouth Bt-horizon soil (Typic Umbraquaalts, fine loamy, mixed, thermic pH 5.2), they were 1, 0.67, 0.67, 0.7, 0.59, 0.38, 0.35, and 0.13, respectively.19 The differences in phytotoxicity of the individual phenolic acids for nutrient culture and Portsmouth soil bioassays were due to various soil processes listed in the next paragraph and reduced contact (e.g., distribution and movement)36 of phenolic acids with roots in soils. 

Blum, U. and Dalton, B. R., 1985. Effects of ferulic acid, an allelopathic compound, on leaf expansion of cucumber seedlings grown in nutrient culture. J. Chem. Ecol. 11, 279-301... 

Excess Na ions in the soil solution can be inhibitory to certain plant processes. Plant sensitivity to various Na levels in soil is dependent on plant species and stage of plant development. Sodium toxicity to higher plants is characterized by leaf-tip burn, necrotic spots, and limited leaf expansion, thus reducing yield. 

Meiri, A. and A. Poljakoff-Mayber. 1970. Effect of various alinity regimes on growth. Leaf expansion and transpiration rate of bean plants. Soil Sci. 109 26-34. 

Neumann, P. M., E. van Volkenburgh, and R. E. Cleland, 1988, Salinity stress inhibits bean leaf expansion by reducing turgor, not wall extensibility. Plant Physiol. 88 233-237. 

The purine is s)mthesized and stored in large quantities in the seed. Directly after germination, caffeine remains in the cotyledons surrounding the endosperm and does not migrate to the h)7pocotyl or root. In older seedlings, caffeine accumulation continues during leaf expansion, and in the mature plant the fruits actively synthesize purine alkaloids as they mature (Aerts and Baumann, 1994). 

Gross Structure and Histology of Different Types of Dorsonentral Leaf Blades.—i. Umbrophytic.—Characterized by leaveo mostly undivided and having the largest and most continuous leaf expanse. Usually the deepest green leaves we have, to enable the leaves to... 

Since the discovery of cytokinins, different adenylate and non-adenylate compounds have been synthesized and classified as potent anticytokinins based on the reduction of cytokinin effects, i.e. chlorophyll retention, radish leaf expansion and callus growth. 

Kamaluddin, M. and J.J. Zwiazk. 2003. Fluoride inhibit root water transport and affects leaf expansion ad gas exchange in aspen (Populus tremuloides) seedlings. Physiol. Plant. 117(3) 368-375. 

The photosynthetic efficiency mainly depends on the openness of stomata, particularly in C3 crops, while their closure tends to avoid excessive water loss. Abscisic acid (ABA) mediates water loss from the guardian cells of the stomata, which is triggered by a decrease in the water content of the leaf and inhibits leaf expansion. In muskmelon seedlings, ABA could improve the maintenance of the leaf water potential and relative water content, and reduce electrolyte leakage [55]. 

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