In experiments with tobacco tissue cultured on White's modified medium (basal meditmi hi Tnhles 1 and 2) supplemenk'd with kiticthi and hidoleacctic acid, a slrikin^' fourlo (ive-told intTease iu yield was ohtaitu-d within a three to Tour week j^rowth period on addition of an aqtteotis exlrarl of tobacco leaves (Fi^'ures 1 and 2). Subse(iueutly it was found Ihiit this jnoniotiou oi' f^rowih was due mainly though nol entirely to inorj^auic rather than organic con.stitttenls in the extract. In the isolation of Rrowth factors from plant tissues and other sources inorj '̂anic salts are fre(|uently carried along with fhe organic fraclioits. When tissue cultures are used for bioassays, therefore, il is necessary lo lake into account increases in growth which may result from nutrient elements or other known constituents of the medium which may he present in the te.st materials. To minimize interference trom rontaminaitis of this type, an altempt has heen made to de\\eh)p a nieditmi with such adequate supplies of all re(iuired tnineral nutrients and cotntnott orgattic cottslitueitls that no apprecial»le change in growth rate or yield will result from the inlroduclion of additional amounts in the range ordinarily expected to be present in tnaterials to be assayed. As a point of referetice for this work some of the culture media in mc)st common current use will he cotisidered briefly. For ease of comparis4)n Iheir mineral compositions are listed in Tables 1 and 2. White's nutrient .solution, designed originally for excised root cultures, was based on Uspeuski and Uspetiskaia's medium for algae and Trelease and Trelease's micronutrieni solution. This medium also was employed successfully in the original cttltivation of callus from the tobacco Iiybrid Nicotiana gtauca x A', tanijadorffii, atitl as further modified by White in 194̂ ^ and by others it has been used for the

A revised medium for rapid growth and bio assays with tobacco tissue cultures

1. Plant Nutrients. 2. The Soil as a Plant Nutrient Medium. 3. Nutrient Uptake and Assimilation. 4. Plant Water Relationships. 5. Plant Growth and Crop Production. 6. Fertilizer Application. 7. Nitrogen. 8. Sulphur. 9. Phosphorus. 10. Potassium. 11. Calcium. 12. Magnesium. 13. Iron. 14. Manganese. 15. Zinc. 16. Copper. 17. Molybdenum. 18. Boron. 19. Further Elements of Importance. 20. Elements with More Toxic Effects. General Readings. References. Index.

/pdf/principles-of-plant-nutrition-2k4wl46ou6.pdf

Principles of plant nutrition

There is growing recognition that classifying terrestrial plant species on the basis of their function (into 'functional types') rather than their higher taxonomic identity, is a promising way forward for tackling important ecological questions at the scale of ecosystems, landscapes or biomes. These questions include those on vegetation responses to and vegetation effects on, environmental changes (e.g. changes in climate, atmospheric chemistry, land use or other disturbances). There is also growing consensus about a shortlist of plant traits that should underlie such functional plant classifications, because they have strong predictive power of important ecosystem responses to environmental change and/or they themselves have strong impacts on ecosystem processes. The most favoured traits are those that are also relatively easy and inexpensive to measure for large numbers of plant species. Large international research efforts, promoted by the IGBP–GCTE Programme, are underway to screen predominant plant species in various ecosystems and biomes worldwide for such traits. This paper provides an international methodological protocol aimed at standardising this research effort, based on consensus among a broad group of scientists in this field. It features a practical handbook with step-by-step recipes, with relatively brief information about the ecological context, for 28 functional traits recognised as critical for tackling large-scale ecological questions.

/pdf/a-handbook-of-protocols-for-standardised-and-easy-2uo4112zhh.pdf

A handbook of protocols for standardised and easy measurement of plant functional traits worldwide

The nitrogen content of a plant is only one of the many plant characteristics that are vitally important to herbivores. However, because of its central role in all metabolic processes as well as in cellular structure and genetic coding, nitrogen is a critical element in the growth of all organisms. Supplementary N often elicits enhanced health, growth, reproduction, and survival in many organisms. This suggests that N is a limiting factor. Since N makes up a large portion of the earth's atmosphere (about 78%), the problem is not an absolute but a relative shortage-that is, a scarcity of usable or metaboliza­ ble N during critical growth periods (159, 328). Plants encounter shortages of inorganic nitrogen (nitrate and/or ammonium ions); animals experience shortages of organic nitrogen (specific proteins and/or amino acids). This article reviews and examines the evidence (a) that N is scarce and perhaps a limiting nutrient for many herbivores, and (b) that in response to this selection pressure, many herbivores have evolved specific behavioral, morphological, physiological, and other adaptations to cope with and uti­ lize the ambient N levels of their normal haunts. McNeill & Southwood (201) and White (328) have also reviewed these general questions. There­ fore, this review explores additional evidence and further develops the fundamental arguments. The review is organized into three major divisions. The first focuses on important sources of variation in plant N (seasonal and ontogenetic trends, different tissues and species, etc) because such variation may be the basis

Herbivory in relation to plant nitrogen content

Contents
I. Introduction  424
II. The phosphorus conundrum 424
III. Adaptations to low P 424
IV. Uptake of P  424
V. P deficiency alters root development and function 426
VI. P deficiency modifies carbon metabolism 431
VII. Acid phosphatase 436
VIII. Genetic regulation of P responsive genes 437
IX. Improving P acquisition 439
X. Synopsis  440


Summary
Phosphorus (P) is limiting for crop yield on > 30% of the world's arable land and, by some estimates, world resources of inexpensive P may be depleted by 2050. Improvement of P acquisition and use by plants is critical for economic, humanitarian and environmental reasons. Plants have evolved a diverse array of strategies to obtain adequate P under limiting conditions, including modifications to root architecture, carbon metabolism and membrane structure, exudation of low molecular weight organic acids, protons and enzymes, and enhanced expression of the numerous genes involved in low-P adaptation. These adaptations may be less pronounced in mycorrhizal-associated plants. The formation of cluster roots under P-stress by the nonmycorrhizal species white lupin (Lupinus albus), and the accompanying biochemical changes exemplify many of the plant adaptations that enhance P acquisition and use. Physiological, biochemical, and molecular studies of white lupin and other species response to P-deficiency have identified targets that may be useful for plant improvement. Genomic approaches involving identification of expressed sequence tags (ESTs) found under low-P stress may also yield target sites for plant improvement. Interdisciplinary studies uniting plant breeding, biochemistry, soil science, and genetics under the large umbrella of genomics are prerequisite for rapid progress in improving nutrient acquisition and use in plants.

/pdf/phosphorus-acquisition-and-use-critical-adaptations-by-56im8qzi8m.pdf

Phosphorus acquisition and use: critical adaptations by plants for securing a nonrenewable resource

The soil actinomycete causing formation of nitrogen-fixing symbiotic nodules on roots of the woody angiosperm Comptonia peregrina (L.) Coult. (Myricaceae) has been isolated from surface-sterilized root nodules after incubation and enzyme maceration. The filamentous bacterium grows slowly in pure culture on a yeast extract medium, producing sporogenous bodies which form large numbers of ovoid spores. Reinfection of sand-grown or aeroponically grown seedlings of Comptonia was achieved repeatedly with inocula prepared from suspensions of the Comptonia isolate. The same actinomycete has been reisolated from these seedling nodules. The induced nodules are highly active in the acetylene-reduction assay, and plants grow vigorously without an exogenous supply of fixed nitrogen.

http://science.sciencemag.org/content/sci/199/4331/899.full.pdf

Isolation and Cultivation in vitro of the Actinomycete Causing Root Nodulation in Comptonia

The development and function of roots.

Kinetics of growth and nitrogenase induction in Frankia sp. ArI3 were studied in batch culture. Growth on defined medium with NH 4 + as the N source displayed typical batch culture kinetics; however, a short stationary phase was followed by autolysis. Removal of NH 4 + arrested growth and initiated vesicle differentiation. Vesicle numbers increased linearly and were paralleled by a rise in nitrogenase (acetylene reduction) activity. Nitrogenase activity (10 mM C2H4 · mg protein−1 · min−1) was sufficient to support growth on N2 and protein levels rose in parallel with nitrogenase induction. Optimal conditions for vesicle and nitrogenase induction were investigated. Maximum rates of acetylene reduction were obtained with 5 to 10 mM K2 HPO4/KH2PO4, 0.1 mM CaCl2 and MgSO4. The optimum pH for acetylene reduction and respiration was around 6.7. The amount (5 to 10µg protein/ml) and stage (exponential) of growth of the ammonium-grown inoculum strongly influenced the subsequent development of nitrogenase activity. Propionate was the most effective carbon source tested for nitrogenase induction. Respiration in propionate-grown cells was stimulated by CO2 and biotin, suggesting that propionate is metabolized via the propionyl CoA pathway.

Growth kinetics and nitrogenase induction in Frankia sp. HFPArI 3 grown in batch culture

Root hair infection of Trifolium repens L. by Rhizobium trifolii was investigated with regard to the structural basis of infection thread origin. Most infected root hairs were shown to have in comm...

/pdf/the-structural-basis-for-infection-of-root-hairs-of-47tpsw2l6y.pdf

The structural basis for infection of root hairs of Trifolium repens by Rhizobium

The isolations of three new strains of Frankia were made from root nodules of Casuarina cunninghamiana growing aeroponically. Two strains, HFPCcI1 and HFPCcI2 isolated by Lopez are typical Frankia strains, producing sporangia among filamentous mats in culture and, in the absence of combined nitrogen, forming vesicles and showing acetylene reduction. They are red-pigmented and, although failing to nodulate Casuarina hosts, effectively nodulated Elaeagnus and Hippophae. A third strain HFPCcI3 isolated by Zhang from the same source, also a typical Frankia, can form sporangia and vesicles in culture and reduce acetylene, is unpigmented, fails to nodulate Elaeagnus but effectively nodulates C. cunninghamiana and C. equisetifolia. Comparisons are made among all of the Casuarina isolates in our collection from around the world (twelve in all) with regard to their cultural characteristics and capacity to infect host plant species. Questions are raised about the specificity of the various isolates and their possible affinities. Opportunities are suggested for inoculation of seedlings for forestry and field application using the infective, effective strains now available.

John G. Torrey

Papers

Isolation and Cultivation in vitro of the Actinomycete Causing Root Nodulation in Comptonia

The development and function of roots.

Growth kinetics and nitrogenase induction in Frankia sp. HFPArI 3 grown in batch culture

The structural basis for infection of root hairs of Trifolium repens by Rhizobium

A comparison of cultural characteristics and infectivity of Frankia isolates from root nodules of Casuarina species