Structure of Protein Bodies and Elemental Composition of Phytin from Dry Germ of Maize (<i>Zea mays</i> L.)

Mikušs, M.; Bobák, M.; Lee, Alexander

doi:10.1111/j.1438-8677.1992.tb00263.x

Cited by 22 publications

(11 citation statements)

References 33 publications

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“…6H), and their mineral composition was similar to that reported for phytate (Mikus et al, 1992). Phytate or polyphosphate deposits in the vacuoles may be involved in vacuolar storage of Al in a way similar to that reported for Zn (Van Steveninck et al, 1987).…”

Section: Discussionsupporting

confidence: 62%

Change in Apoplastic Aluminum during the Initial Growth Response to Aluminum by Roots of a Tolerant Maize Variety1

et al. 1999

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Root elongation, hematoxylin staining, and changes in the ultrastructure of root-tip cells of an Al-tolerant maize variety (Zea mays L. C 525 M) exposed to nutrient solutions with 20 M Al (2.1 M Al 3؉ activity) for 0, 4, and 24 h were investigated in relation to the subcellular distribution of Al using scanning transmission electron microscopy and energy-dispersive x-ray microanalysis on samples fixed by different methods. Inhibition of root-elongation rates, hematoxylin staining, cell wall thickening, and disturbance of the distribution of pyroantimoniate-stainable cations, mainly Ca, was observed only after 4 and not after 24 h of exposure to Al. The occurrence of these transient, toxic Al effects on root elongation and in cell walls was accompanied by the presence of solid Al-P deposits in the walls. Whereas no Al was detectable in cell walls after 24 h, an increase of vacuolar Al was observed after 4 h of exposure. After 24 h, a higher amount of electron-dense deposits containing Al and P or Si was observed in the vacuoles. These results indicate that in this tropical maize variety, tolerance mechanisms that cause a change in apoplastic Al must be active. Our data support the hypothesis that in Al-tolerant plants, Al can rapidly cross the plasma membrane; these data clearly contradict the former conclusions that Al mainly accumulates in the apoplast and enters the symplast only after severe cell damage has occurred.It is largely recognized that root tips are the primary site of Al-induced injury in plants (Ryan et al., 1993). The accumulation of Al in root tips has been found to be significantly correlated with root-growth inhibition in maize (Zea mays L.) varieties differing in Al tolerance (Llugany, 1994; Llugany et al., 1994). In Al-sensitive maize plants an inhibition of root elongation has been observed after only 30 min of exposure to Al (Llugany et al., 1995). Such a short response time, in addition to the common belief (Kochian, 1995) that Al accumulates mainly in the apoplast and crosses the plasma membrane slowly, has led to the hypothesis that Al-induced inhibition of root elongation may be caused by toxicity mechanisms that occur in the apoplast (Rengel, 1990(Rengel, , 1996 Horst, 1995) and that there is no need for Al to enter the symplast to cause primary toxicity effects (Rengel, 1992). However, investigations using the highly Al-sensitive technique of secondary ion MS have shown that significant Al concentrations accumulate in the symplast of root-tip cells of soybean plants after only 30 min of exposure to Al (Lazof et al., 1994(Lazof et al., , 1996. Recent experiments on giant algae (Chara corallina) cells, where cell walls were separated from the cells by microsurgery, have also shown that Al uptake across the plasmalemma may be linear and occurs without delay (Rengel and Reid, 1997). These investigations support the view that symplastic phytotoxicity mechanisms may also be responsible for Alinduced inhibition of root elongation after short exposure times (Kochian, 1995).More information...

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Section: Discussionsupporting

confidence: 62%

Change in Apoplastic Aluminum during the Initial Growth Response to Aluminum by Roots of a Tolerant Maize Variety1

et al. 1999

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“…Phytate (myo-inositol hexakisphosphate) is the principal form of reserve phosphorous in plants (Hocking and Pate 1977) and is often localized in the roots and seeds (van Steveninck et al 1993;Hubel and Beck 1996) (Mikus et al 1992). The distribution of phytate and its ability to chelate multiple metal species suggest it could be mobilized as a detoxification strategy.…”

Section: Organic Acids Amino Acids and Phosphate Derivativesmentioning

confidence: 99%

Plant Responses to Heavy Metal Toxicity

Manara

2012

SpringerBriefs in Molecular Science

194

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Plants, like all other organisms, have evolved different mechanisms to maintain physiological concentrations of essential metal ions and to minimize exposure to non-essential heavy metals. Some mechanisms are ubiquitous because they are also required for general metal homeostasis, and they minimize the damage caused by high concentrations of heavy metals in plants by detoxification, thereby conferring tolerance to heavy metal stress. Other mechanisms target individual metal ions (indeed some plants have more than one mechanism to prevent the accumulation of specific metals) and these processes may involve the exclusion of particular metals from the intracellular environment or the sequestration of toxic ions within compartments to isolate them from sensitive cellular components. As a first line of defense, many plants exposed to toxic concentrations of metal ions attempt to prevent or reduce uptake into root cells by restricting metal ions to the apoplast, binding them to the cell wall or to cellular exudates, or by inhibiting long distance transport. If this fails, metals already in the cell are addressed using a range of storage and detoxification strategies, including metal transport, chelation, trafficking, and sequestration into the vacuole. When these options are exhausted, plants activate oxidative stress defense mechanisms and the synthesis of stress-related proteins and signaling molecules, such as heat shock proteins, hormones, and reactive oxygen species.

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“…Considerable variability in PBs structure described for the cells of Echinocactus was observed also in other species from different families (e.g. Protodermal cells containing PBs with a simpler structure (lacking GCs) were found also in maize and barley (Lux et al, 1992;Miku~ et al, 1992). This PBs variability is caused by differences in the structure of the matrix and the presence of different number of GCs varying in their size.…”

Section: Discussionmentioning

confidence: 83%

“…Semi-thin 0.5-IJ,tm sections were stained with toluidine blue or toluidine blue and basic fuchsin (Lux, 1981) and were examined by LM. The elemental composition of globoid crystals was determined with EDX analysis system LINK AN 10/85 S using identical parameters as described before (Mikus et al, 1992). Our preparation procedure for X-ray microanalysis differs from that published by Lott et al (1984) since partial leach out of materials must be considered (Skilnyk and Lott, 1992).…”

Section: Methodsmentioning

confidence: 99%

“…(1992), although observing little difference between root and shoot in the degree of accumulation of Cd and Zn in the Cd/Zn hyper-accumulator Thlaspi caeruiescens, found that Cd was accumulated mainly in the apoplast whereas Zn was principally found in vacuoles. Considering that inner cortical cells in the root elongation zone of Zn-tolerant Deschampsia caespitosa are capable of binding Zn by means of phytate (Van Steveninck et aI., 1987), and that this trait has now been shown to occur in the radicle of maize seeds (Mikus et al, 1992) and in the root endodermis (dicots) or pericycle (monocots) of a wide range of crop plants (Van Steveninck et aI., 1993), it seemed worthwhile to check whether or not these plant species are capable of binding Cd by the same means. (1990a) produced evidence for two distinct mechanisms of Zn and Cd binding in young fronds of the aquatic plant Lemna minor, but in mature frond tissue, Zn and Cd could both be bound by means of phytate (Van Steveninck et aI., 1992).…”

Section: Introductionmentioning

confidence: 99%

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