Functional Aspects of Boron in Plants

Dugger, W. M.

doi:10.1021/ba-1973-0123.ch007

Cited by 36 publications

(25 citation statements)

References 47 publications

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“…Such a mechanism could also be concerned with conversion oi ieruhte to hydroxyieruhte. Consistent with this suggestion is the accumulation of quinones and melanitic granules, and increased activities of catechol and polyphenol oxidases, in boron-deficient tissues (Dugger, 1973 Fig. 4.…”

Section: The Symptoms Of Boron Deficiency and Their Relevance To The supporting

confidence: 65%

“…Freedom from requirement for external water for sexual reproduction 1958; Skok, 1958;Nason and McElroy, 1963;Hewitt, 1963;Dugger, 1973;Hewitt and Smith, 1975). Among the algae, confirmed reports of essentiality are confined to that of Cylindrotheca fusiformis and a few other diatoms (Lewin, 1965(Lewin, , 1966a.…”

Section: Maximizing Photosynthesis: Transpiration Ratiomentioning

confidence: 99%

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Boron, Lignification and the Origin of Vascular Plants‐a Unified Hypothesis

Lewis

1980

New Phytologist

176

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SUMMARYIt is proposed that the development of an essential role for boron was a prerequisite for the evolution of vascular from prevascular plants since there is a prima facie case that a primary role of boron concerns the biosynthesis of lignin and, in conjunction with auxin, differentiation of xylem. In particular, a potential role for borate in regulating the hydroxylase and oxidase activities of the phenolases involved in the biosynthesis of caffeic and hydroxyferulic acids is suggested. The origin of this role for boron depended on the selection of sucrose in the Chlorophyta as a mobile and storage carbohydrate since, compared with the acyclic sugar alcohols accumulated in other algal groups, sucrose forms only a very weak complex with borate. It is argued that only when borate was not sequestered by complexing with other carbohydrates did the way become clear for it to acquire an essential role. This acquisition catalysed the evolutionary dichotomy between non-lignified and lignified photosynthetic landplants, the bryophytes and tracheophytes. Boron subsequently became involved in two other requirements for success on land -the exploitation of soil for anchorage, water and minerals, and the emancipation of fertilization from external water-since this element is required for development of adventitious roots (again in conjunction with plant hormones) and, in angiospertns, for germination of pollen.

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Section: The Symptoms Of Boron Deficiency and Their Relevance To The supporting

confidence: 65%

Section: Maximizing Photosynthesis: Transpiration Ratiomentioning

confidence: 99%

Boron, Lignification and the Origin of Vascular Plants‐a Unified Hypothesis

Lewis

1980

New Phytologist

176

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“…It is reported to be involved in numerous physiological and biochemical processes including cell division, nucleic acid metabolism, sugar synthesis and translocation, protein synthesis, cell wall synthesis, auxin and phenolic compound metabolism, and membrane functions (Dugger 1973(Dugger , 1983 Shkol'nik 1974; Pilbeam and Kirkby 1983). However, the primary role of B and its mode of action remain unknown.…”

mentioning

confidence: 99%

Boron nutrition and the composition of glucosinolates and soluble nitrogen compounds in two broccoli (Brassica oleracea var. italica) cultivars

Shelp¹,

Shattuck²,

McLellan³

et al. 1992

Can. J. Plant Sci.

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and 'Commander') plants were grown in the glasshouse from January to April under the environmental and nutrient conditions essentially as described by Shelp et al. (1992). The only exception was the B application, which was supplied continuously at 0.0. 1.0.25.0.5. 1.0 or 2.5 mg B L-' in the nutrient solution.Plants were harvested at maturity, just before bud opening at the time of maximum expansion of the inflorescence (72-80 and 78-93 d after sowing for Baccus and Commander, respectively; also designated as commercial harvest date). The two oldest leaves and the 4-6 youngest leaves weighing greater than 0.5 g were removed from each plant and deveined. One-half of each leaf or the inflorescence was frozen in liquid nitrogen and stored at -20"C for no longer than 2 wk. The RESULTS Infl orescence CharacteristicsThe inflorescence characteristics at commercial maturity are shown for the two cultivars For personal use only.

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“…One of the more recurrent proposals for a role of boron in higher plants is that it may play a part in IAA metabolism and thereby influence growth (5). Eaton (7) obtained evidence that led him to conclude that boron-deficient plants were also IAAdeficient.…”

mentioning

confidence: 99%

Early Effects of Boron Deficiency on Indoleacetic Acid Oxidase Levels of Squash Root Tips

Bohnsack¹,

Albert²

1977

Plant Physiol.

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The indoleacetic acid (IAA) oxidase activity of root tips of boronsufficient, -deficient, recovering, and IAA-treated boron-sufficient squash plants (Cucurbita pepo L.) was determined. Apical and subapical root sections displayed an increase in IAA oxase activity between 6 and 9 hours after boron was withheld, and after 24 hours the activity of the apical sections showed a 20-fold increase over +B controls. Root elongation of -B plants was inhibited before an increase in oxidase activity could be detected. Roots One of the more recurrent proposals for a role of boron in higher plants is that it may play a part in IAA metabolism and thereby influence growth (5). Eaton (7) obtained evidence that led him to conclude that boron-deficient plants were also IAAdeficient. Attempts to confirm Eaton's work, however, have been unsuccessful (10, 12). More recently, Neales (14) proposed that instead of boron-deficient plants lacking sufficient IAA, they may actually contain supraoptimal levels which impair normal growth. Shkol'nik et al. (19) reported a decrease in the level of free acid auxins and an increase in the bound form in deficient corn and sunflower plants. Other investigators have reported higher levels of IAA in the apical regions of borondeficient plants and have speculated that the increase in IAA might be due to an inactivation or change in the activity of IAA oxidase (4, 9).Oxidative enzyme activity appears to be altered by boron deficiency. Higher polyphenol oxidase activity and an increased 02 consumption by tissue homogenates have been reported for boron-deficient plants (11,16). Peroxidase activity of tissue homogenates (13) and of root tips (15) has been found to increase, and to the contrary, decrease in stem callus and root cultures (6). IAA oxidase activity has been reported to decrease in plants subjected to several days of boron deficiency (19).Due to the conflicting nature of these reports and because of its role in IAA metabolism, it was decided to investigate the relationship between boron deficiency and IAA oxidase activity Determination of IAA Oxidase Activity. The in vivo IAA oxidase activity of squash root sections was determined using a modified technique of Galston and Dalbert (8). Fifty each of 5-mm apical and 5-mm subapical root sections were excised and quickly placed in separate incubation flasks containing 10 ml of 2,4-dichlorophenol (10-5 M), IAA (40 ,tg/ml), and citric acid phosphate buffer (pH 5.6) solution. The flasks were placed in a water bath shaker (30 C + 1 at 130 rpm) for 1 hr. Where results of preliminary experiments indicated considerable enzymic activity, the number of root sections/flask was reduced to 25 and the incubation time to 0.5 hr.When incubation was complete, the flasks were removed from the water bath and the solution in the flask tested for residual IAA. Aliquots of the solution were placed in test tubes with Salkowski reagent (50 ml 35% perchloric acid-I ml 0.5 M Fe2CL3) and allowed to develop for 1 hr. Absorbance was measured on a Gilford spectropho...

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Functional Aspects of Boron in Plants

Cited by 36 publications

References 47 publications

Boron, Lignification and the Origin of Vascular Plants‐a Unified Hypothesis

Boron, Lignification and the Origin of Vascular Plants‐a Unified Hypothesis

Boron nutrition and the composition of glucosinolates and soluble nitrogen compounds in two broccoli (Brassica oleracea var. italica) cultivars

Early Effects of Boron Deficiency on Indoleacetic Acid Oxidase Levels of Squash Root Tips

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