Root hairs and phycomycetous mycorrhizas in phosphorus-deficient soil.
01 Aug 1970-Plant and Soil (Martinus Nijhoff, The Hague/Kluwer Academic Publishers)-Vol. 33, Iss: 1, pp 713-716
TL;DR: Coprosma robusta formed phycomycetous mycorrhizas in unsteamed forest soil and grew equally well with or without added phosphate, and in steamed soil it did not grow unless phosphate was added.
Abstract: Coprosma robusta formed phycomycetous mycorrhizas in unsteamed forest soil and grew equally well with or without added phosphate. In steamed soil it did not grow unless phosphate was added. Of the other species tested (Leptospermum scoparium, Solanum nigrum, Lolium perenne, Hakea enkiantha, Histiopteris incisa, Marchantia berteroana) most formed mycorrhizas in unsteamed soil, but all grew better in steamed soil. The dry matter of the mycorrhizal Coprosma seedlings contained the highest concentration of phosphorus, but the relatively large plants that the other species produced in steamed soil contained a greater total quantity. It is suggested that this entered mainly through their extensive root hairs (or rhizoids), and that lack of root hairs in Coprosma and other woody species explains their need for added phosphate when mycorrhizas are not formed.
Citations
More filters
TL;DR: A survey of 659 papers mostly published since 1987 was conducted to compile a checklist of mycorrhizal occurrence among 3,617 species (263 families) of land plants and a plant phylogeny was then used to map the mycor rhizal information to examine evolutionary patterns.
Abstract: A survey of 659 papers mostly published since 1987 was conducted to compile a checklist of mycorrhizal occurrence among 3,617 species (263 families) of land plants. A plant phylogeny was then used to map the mycorrhizal information to examine evolutionary patterns. Several findings from this survey enhance our understanding of the roles of mycorrhizas in the origin and subsequent diversification of land plants. First, 80 and 92% of surveyed land plant species and families are mycorrhizal. Second, arbuscular mycorrhiza (AM) is the predominant and ancestral type of mycorrhiza in land plants. Its occurrence in a vast majority of land plants and early-diverging lineages of liverworts suggests that the origin of AM probably coincided with the origin of land plants. Third, ectomycorrhiza (ECM) and its derived types independently evolved from AM many times through parallel evolution. Coevolution between plant and fungal partners in ECM and its derived types has probably contributed to diversification of both plant hosts and fungal symbionts. Fourth, mycoheterotrophy and loss of the mycorrhizal condition also evolved many times independently in land plants through parallel evolution.
1,653 citations
Cites background from "Root hairs and phycomycetous mycorr..."
...It has been suggested that root hairs and mycorrhizal fungi were two alternative mechanisms for plant nutrient uptake (Baylis 1970; Koide 1991)....
[...]
TL;DR: Mycorrhizal plants have been shown to increase the uptake of poorly soluble P sources, such as iron and aluminium phosphate and rock phosphates, however, studies in which the soil P has been labelled with radioactive 32P indicated that both mycor rhizal and non-mycorrhIZal plants utilized the similarly labelled P sources in soil.
Abstract: The beneficial effects of mycorrhizae on plant growth have often been related to the increase in the uptake of immobile nutrients, especially phosphorus (P). In this review the mechanisms for the increase in the uptake of P by mycorrhizae and the sources of soil P for mycorrhizal and non-mycorrhizal plants are examined. Various mechanisms have been suggested for the increase in the uptake of P by mycorrhizal plants. These include: exploration of larger soil volume; faster movement of P into mycorrhizal hyphae; and solubilization of soil phosphorus. Exploration of larger soil volume by mycorrhizal plants is achieved by decreasing the distance that P ions must diffuse to plant roots and by increasing the surface area for absorption. Faster movement of P into mycorrhizal hyphae is achieved by increasing the affinity for P ions and by decreasing the threshold concentration required for absorption of P. Solubilization of soil P is achieved by the release of organic acids and phosphatase enzymes. Mycorrhizal plants have been shown to increase the uptake of poorly soluble P sources, such as iron and aluminium phosphate and rock phosphates. However, studies in which the soil P has been labelled with radioactive 32P indicated that both mycorrhizal and non-mycorrhizal plants utilized the similarly labelled P sources in soil.
1,143 citations
Cites background or methods from "Root hairs and phycomycetous mycorr..."
...The difference in concentration of P between the fungus and the host determines the direction and rate of transport. Translocation of P within the hyphae occurs passively down a concentration gradient between the P source in the external hyphae and a sink in the root. Cytoplasmic streaming is involved in the movement of P within the hyphae (Harley and Smith, 1983). A high concentration of P in the fungus is maintained by the hydrolysis of polyphosphate. Polyphosphate is broken down by polyphosphatases or by reversal of polyphosphate kinase (Capaccio and Callow, 1982; Cox et al., 1980). Recently, Smith and Gianinazzi-Pearson (1988) have proposed that bidirectional transfer of Pi and carbohydrates occurs between the root and the hyphae at the fungus-root interface which involves both passive and active transfer processes....
[...]
...This should provide information on the availability of different fractions of P for uptake by mycorrhizal and non-mycorrhizal plants (Swaminathan, 1979). However, as indicated earlier, change in one fraction due to plant uptake can alter another fraction which can make it difficult to identify the sources of soil P for plant uptake. Sainz and Arines (1988b) measured different fractions of inorganic P after growing both mycorrhizal and non-mycorrhizal plants for 6 months....
[...]
...These findings have led to the conclusion that mycorrhizal plants may use more carbon for purposes other than growth of photosynthate tissue. Stribley et al. (1980) suggested that weight loss in mycorrhizal plants was associated with the drain of energy by the fungus....
[...]
...This approach has been used by Cassman et al. (1979) to examine the phosphate nutrition of rhizobia....
[...]
..., 1977; Treeby et al., 1989). There is little experimental evidence for direct chemical modification of P availability by endomycorrhizal plants (Abbott and Robson, 1982; Gianinazzi-Pearson and Gianinazzi, 1978). Parfitt (1979) suggested that the increased uptake of P from goethite - phosphate complexes by mycorrhizal plants might be due to increased production of citrate and other organic compounds. Similarly, Jayachandran et al. (1989) have observed that in the presence of synthetic chelates (EDDHA) mycorrhizae caused greater uptake of P than in the absence of these chelates, whereas non-mycorrhizal plants were unable to take advantage of the P released by chelation....
[...]
TL;DR: Variation among plant taxa in morphological, physiological or phenological traits which affect either phosphorus demand or phosphorus supply (and thus phosphorus deficit) is predicted to lead to variation in potential response to mycorrhizal infection.
Abstract: summary
One of the most dramatic effects of infection by vesicular-arbuscular mycorrhizal fungi on the physiology of the host plant is an increase in phosphorus absorption. When phosphorus is limiting, the maximum extent to which mycorrhizal infection can improve plant performance is thus predicted to be a function of the phosphorus deficit of the plant, the difference between phosphorus demand and phosphorus supply. Phosphorus demand is defined as the rate of phosphorus absorption that would result in optimum performance of the plant as measured by growth rate, reproduction or fitness. The phosphorus supply is defined as the actual rate of phosphorus absorption under the prevailing conditions. Variation among plant taxa in morphological, physiological or phenological traits which affect either phosphorus demand or phosphorus supply (and thus phosphorus deficit) is predicted to lead to variation in potential response to mycorrhizal infection. The actual response to mycorrhizal infection is predicted to be a function of the increase in phosphorus uptake due to mycorrhizal infection and the phosphorus utilization efficiency of the plant. Demonstrated variability in responsiveness to mycorrhizal infection among plant taxa suggests that mycorrhizal fungi may play an important role in determining the structure of plant communities.
Mycorrhizal infection may alter the phosphorus deficit or phosphorus utilization efficiency independently from its direct effect on phosphorus uptake, making the prediction of response to mycorrhizal infection based on the traits of non-mycorrhizal plants quite difficult. For example, infection may at times increase the rate of phosphorus accumulation beyond that which can be currently utilized in growth, reducing the current phosphorus utilization efficiency. Such momentary ‘luxury consumption’ of phosphorus may, however, serve a storage function and be utilized subsequently, allowing mycorrhizal plants ultimately to outperform non-mycorrhizal plants.
521 citations
TL;DR: The competitive relationships between grasses and legumes are examined and the way in which pasture management techniques alter the balance of legumes and grasses by manipulating the environment is considered, which results in a competitive advantage to the legume component.
Abstract: Publisher Summary A grass-legume association has been used in many countries of the world because a greater total herbage yield may be obtained by growing a grass and a legume in association, rather than in individual swards, where no fertilizer N is applied. Interferences and competition between legumes and associated grasses are of great importance in world pasture production. Such interspecific interferences are likely to be a dominating factor in the nonequilibrium, man-made and -managed pasture vegetation. It is generally accepted that grasses normally have a competitive advantage over legumes, and they tend to dominate pastures but to maintain high pasture productivity, a balance between grasses and legumes is desirable. This chapter examines the competitive relationships between grasses and legumes and also considers the way in which pasture management techniques alter the balance of legumes and grasses by manipulating the environment, which results in a competitive advantage to the legume component.
371 citations
TL;DR: The major constraints to nutrient uptake by vascular plants in mediterranean South Africa and Western Australia are: very infertile soils, relatively low temperatures when water availability is high, and hot, dry summers are partly overcome through increased efficiency of uptake, tapping novel sources of nutrients, and prolonging water uptake.
Abstract: The major constraints to nutrient uptake by vascular plants in mediterranean South Africa and Western Australia are: very infertile soils, relatively low temperatures when water availability is high, and hot, dry summers. These constraints are partly overcome through increased efficiency of uptake, tapping novel sources of nutrients, and prolonging water uptake. Absorptive area per unit “cost” may be enlarged directly through increased fineness of the root system and proliferation of long root hairs. This reaches its greatest development in the root clusters of the Proteaceae (proteoid roots), Restionaceae (“capillaroid” roots) and Cyperaceae (dauciform roots). Absorptive area is increased indirectly through fungal hyphae which extend from hairless rootlets into the soil. Two major groups can be recognised: general (VA mycorrhizas) and host-specific (ericoid, orchid and sheathing mycorrhizas). Mycorrhizas are the most widespread specialised modes of nutrition and are probably universal in such major taxa here asPodocarpus, Acacia, Fabaceae, Poaceae, Asteraceae, Rutaceae, terrestrial orchids, Ericales and Myrtaceae. General mycorrhizas are the least drought-adapted of mechanisms for maximising absorptive area. All have been implicated in enhancing P uptake through increasing access to inorganic P, solubilisation and shortening the diffusion path. However, selective uptake of other nutrients, especially N, by host-specific mycorrhizas may be equally important. Included under novel sources of nutrients are free N2 (utilised by N2-fixing nodules), small-animal prey (carnivorous leaves) and persistent leaf bases (aerial roots ofKingia australis). Both legume and non-legume N2-fixing species are well-represented in these two regions, with stands of individual species in southwestern Australia estimated to contribute 2–19 kg N/ha/yr to the ecosystem. Free nitrogen fixation requires additional nutrients, especially Mo and Co, but is enhanced following fires and by supplementary uptake mechanisms, especially VA mycorrhizas. Southwestern Australia is particularly rich in carnivorous species. Nitrogen, P, K and S are important nutrients absorbed, with digestion aided by enzymes provided by bacteria and the glands. Parasitic plants both tap novel sources of nutrients and capitalise on any efficient water and nutrient uptake mechanisms of the hosts. Root parasites are better represented than stem parasites in mediterranean South Africa and Western Australia. Phosphorus and K in particular are absorbed preferentially by the haustoria, but much remains to be known about their modes of operation. Maximum activity of all uptake mechanisms, except those attached to some deep-rooted plants, is restricted to winter-spring. Most new seasons’s rootlets and specialised roots are confined to the uppermost 15 cm of soil, especially in or near the decomposing litter zone. Nutrient uptake is further enhanced by the tendency for the rootlets to cluster, trapping water by capillary action and prolonging nutrient release. As an early product of decomposition, N tends to be available as NH4 (rather than NO3) and it is absorbed preferentially by almost all specialised modes of nutrition. Microorganisms are required in the formation and/or functioning of all these structures, except haustoria. Uptake mechanisms which are optional to the plant reach their peak contribution to the root system at soil nutrient levels well below those required for greatest plant growth, when they may be absent altogether. It is only over the narrow range of nutrient availability, where shoot content of a nutrient is greater in the presence of the mechanism than in its absence (other factors remaining constant), that specialised modes can be termed nutrient-uptake “strategies.” For all specialised modes of nutrition, the component genera are better represented in these two regions than in the surrounding more fertile, arid to subtropical regions of much greater area. Endemism of species with each mode exceeds that for the two floras overall (75%). This is taken as preliminary evidence that specialised modes of nutrition are best represented in nutrient-poor soils. While they serve to limit nutrient loss from the ecosystem, their proliferation is therefore not necessarily a response to increasing “leaks” in the system. A hierarchical scheme of the functional/structural relationships between the various mechanisms is presented, starting with the rootless, VA-mycorrhizal plant as the most primitive condition. Taxa with many of the specialised modes of nutrition at present in southwestern South Africa and Western Australia have been evident in the pollen record since the early Tertiary Period. The absence of ectomycorrhizal forests in mediterranean South Africa, in marked contrast to Western Australia, can be traced to differences in their paleohistory. In both regions, the combination of fluctuating, but essentially diminishing, nutrient and water availability that began with the first mediterranean climate < 5 million years ago resulted in decimation of the less-tolerant rainforest ancestors on the one hand, and remarkable rates of speciation of the pre-adapted sclerophyll nucleus on the other.
298 citations
References
More filters
Book•
01 Jan 1966
Abstract: Since its appearanc e in 1952, Technical Communication no. 22 of the Commonwealt h Bureau of Horticulture and Plantation Crops has come to be recognized, at least in the English language, as the standar d reference for those interested in the developmen t of sand and water culture techniques used in plant nutrition research throughout the British Commonwealth , parts of Europe, and the United States. The Second Edition of this valuabl e work wil l strengthen even further the unique position it occupies. Most (395 of its 477 pages of text) of the book is devoted to a general review of the subject . A second part deal s in somewhat more detai l with the procedures used by the author at Long Ashton. The completenes s of treatment of the subject matter is best attested by the number of references . Their listing, with complet e titles and cross-indexing , requires 55 pages, which gives an estimated number of 1,800 references . The earliest reference date noted was 1699, the latest , 1964. They are primarily from Great Britain and the United States, but paper s from German, French, Russian, and Japanes e publications are also included. The section devoted to the historical developmen t of plant culture techniques is much longer than in the First Edition. The book represent s very much more than a historical account ing, however . It provides in great detail, and with numerous drawings where appropriate, information on every aspect of plant nutrition research . Likely problems that might be encountere d are presented , and the advantage s and disadvantage s of many of the procedures employed and material s used are discussed . A very useful feature of the book are the conclusions and summaries given after some of the topics are discusse d in detail. It wil l serve well the needs of both the researche r actively engaged in plant nutrition studies as well as the teacher seeking material for classroom presentation . With one important exception, the headings into which the subject matter is divided are identical to those of the earlier edition. However, many sections have been completel y revised, and the more recent findings have been added to practicall y all of them. A 30-page section on the "Assessmen t of contamination and the limitations of micronutrient deficiency studies" is a new and valuable addition to the Second Edition. Much of the material which was previousl y reviewed by R. E. Thiers and R. L. Mitchell is included in this section, but the results of some of the studies at Long Ashton are also presented . In the reviewer' s opinion two features of the book could be improved. I found that it took some time to get accustome d to the numbering system used for chapters , sections, and subsections , and the designation of topics in the index in this manner.Search iri g for topics in the text designate d by this numbering system is much slower than finding them by page number designation. A second shortcoming of the book is the kind of binding used. Unless the copy I received was not typical, the pages are not bound securel y and consequentl y wil l pull loose quite readily. I hope this is not generall y true as I believe that the book wil l be subject to heavy use in any laborator y where plant nutrition studies are being conducted.—V. V. Rendig, Dept, of Soils & Plant Nutrition, University of California, Dans.
2,693 citations
581 citations
TL;DR: The extent of the stimulus obtained depended on nutrient conditions and the subsequent level of infection developed in the root system, and marked stimulation occurred with low phosphate availability and high root infection.
Abstract: Summary
The growth effects of three mycorrhizal Endogone endophytes on tobacco, tomato and maize were examined. The extent of the stimulus obtained depended on nutrient conditions and the subsequent level of infection developed in the root system. Marked stimulation occurred with low phosphate availability and high root infection.
295 citations
TL;DR: The anatomy of the primary root and of roots in which secondary growth has occurred are given and the types of root system found among representative Victorian genera are described.
Abstract: The term ''proteoid root" is defined. The morphological and anatomical features of such roots are described. A shorn account is given of the anatomy of the primary root and of roots in which secondary growth has occurred. The types of root system found among representative Victorian genera are also described.
226 citations
TL;DR: It is suggested that mycorrhizas are normally essential for the uptake of phosphorus from forest soils, the phycomycetous type being particularly important in the Tropics and Southern Hemisphere, where the ectotrophic type has been little recorded.
Abstract: Summary
The mixed rain forest of New Zealand is dominated by conifers and dicotylous trees all of which form phycomycetous mycorrhizas. They may be present only intermittently in the field, but they become conspicuous in seedlings potted in forest soil. The time required to establish infection is variable, and may exceed 1 year. Growth is limited meanwhile by the reserve of phosphorus in the seed.
Heating forest soils to temperatures above 55°C had two contrasted effects on the growth of tree seedlings—a small favourable effect associated with a rise in available phosphate measured hy the Truog test, and a larger deleterious effect associated with destruction of potential endophytes.
Coprosma robusta (Rubiaceae) was the species principally used for experiments. By adding sufficient soluble phosphate to either heated or unheated soil vigorous non-mycorrhizal plants were obtained. In the unheated soil there were also mycorrhizal plants which were, if anything, smaller. With less phosphate plants with numerous mycorrhizas were always larger than those with little or no infection; with no added phosphate there was virtually no growth unless mycorrhizas were formed. The relatively slow-growing Griselinia littoralis differed in that when mycorrhizal it was insensitive to added phosphate. In steamed soil the growth of non-mycorrhizal plants of both species was directly proportional to the amount of phosphate added.
In Coprosma robusta shading to about one-third of full daylight did not reduce mycorrhizal infection.
Chemical analyses are given which demonstrate the low availability of phosphorus in the soils employed, and the greater uptake by mycorrhizal plants.
These observ'ations suggest that mycorrhizas are normally essential for the uptake of phosphorus from forest soils, the phycomycetous type being particularly important in the Tropics and Southern Hemisphere, where the ectotrophic type has been little recorded.
149 citations