Exocellular Enzymes of Corn Roots

Chang, Chong W.; Bandurski, Robert S.

doi:10.1104/pp.39.1.60

Cited by 88 publications

(27 citation statements)

References 31 publications

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“…Nonspecific acid phosphatase has been implicated in tissue differentiation processes (Gahan and Maple, 1966), transport of phosphate, and in hydrolysis and absorption of organic P compounds from soil (Chang and Bandurski, 1964;Rogers et al, 1940). Histochemical techniques have shown Initial pH of buffered solutions was 5.0.…”

Section: Discussionmentioning

confidence: 99%

“…These disintegrating outer cells slough off during passage of a root through soil, thereby protecting the root tip. On the other hand, these hydrolases could solubilize macromolecular constituents of organic matter in soils (Chang and Bandurski, 1964). This could yield low-molecularweight organic and inorganic compounds that could be utilized by plants.…”

Section: Introductionmentioning

confidence: 99%

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Hydrolysis of organic phosphates by corn and soybean roots

Juma

Tabatabai

1988

Plant Soil

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Because of the importance of organic phosphates as sources of P for plants, this work was performed to study the hydrolysis of nine organic phosphates by sterile, intact corn (Zea mays L.) and soybean (Glycine max L.) roots. Results showed that the rates of hydrolysis of p-nitrophenyl phosphate (PNP) in buffered solutions by roots of three varieties of corn and three varieties of soybean ranged from 13 to 22#mol PO4-Pg -I root h-I and from 2.1 to 2.2/1mol PO4-P 0.1 g-I root h -l, respectively. The average rate of hydrolysis of PNP in nonbuffered solutions was 2-to 3-fold lower for corn roots and 6-to 10-fold lower for soybean roots as compared with those obtained with buffered solutions. The orthophosphate released from hydrolysis of organic P compounds in buffered solutions during a 48-h incubation of corn roots showed that the maximum rate of hydrolysis of PNP was 4 to 6 times greater than the commonly used substrates: ct-and fl-glycerophosphates, phenolphthalein diphosphate, and glucose-6-phosphate. The rates of hydrolysis of glucose-6-phosphate and glucose-1-phosphate were similar and about 6-to 12-fold lower than that of PNP. Phosphoethanolamine and phosphocholine were hydrolyzed slightly, and o-carboxyphenyl phosphate was not hydrolyzed. The rates of hydrolysis of organic P compounds in nonbuffered solutions by corn and soybean roots were 1 to 3 and 1 to l0 times lower than those in buffered solutions, respectively. The trends in rates of hydrolysis by soybean roots of buffered organic P substrates were similar to those observed with corn roots, with the exception of glucose-l-phosphate and phosphoethanolamine.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hydrolysis of organic phosphates by corn and soybean roots

Juma

Tabatabai

1988

Plant Soil

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“…The relative fl-glucosidase activities (units/mg wall) Data from several laboratories suggest that glycosidases play a role in wall plasticization, thus permitting cell elongation during extension growth (9). There is evidence that oligosaccharidehydrolyzing enzymes are localized in the walls (1,2,3,7,13,17,19,25) and that these enzymes can hydrolyze cell wall oligosaccharides (12,13, 15,18,25). It becomes important to know whether walllocalized glycosidase activity is correlated with the growth rate of the tissue from which the walls are prepared.…”

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confidence: 99%

Correlative Studies of Cell Wall Enzymes and Growth

Murray

Bandurski²

1975

Plant Physiol.

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If cell wall hydrolytic enzymes are involv-ed in extension growth, a correlation may be expected between hydrolytic activity of the cell walls and growth rate of the tissue from which the walls are prepared. Epicotyl sections from 0 to 5 mm, 6 to 10 mm, and 11 to 13 mm below the apical hook of pea seedlings (Pisum sativum var. Alaska) have relative growth rates of 100:15:2, respectivelv. The relative fl-glucosidase activities (units/mg wall) Data from several laboratories suggest that glycosidases play a role in wall plasticization, thus permitting cell elongation during extension growth (9). There is evidence that oligosaccharidehydrolyzing enzymes are localized in the walls (1,2,3,7,13,17,19,25) and that these enzymes can hydrolyze cell wall oligosaccharides (12,13, 15,18,25). It becomes important to know whether walllocalized glycosidase activity is correlated with the growth rate of the tissue from which the walls are prepared. Previous studies, mainly employing enzymes extracted from wall preparations (7,13,19,25), report that the amount of glycosidase activity correlates with the growth rate of the tissue from which the walls are prepared. In this current study, highly purified cell walls from Pisum epicotyls were utilized, thus permitting specific activity determinations. We find that (3-glucosidase specific activity is highest in walls from rapidly elongating tissue but that surface sterilized in 1 % sodium hypochlorite for 15 min, soaked in running tap water for 18 hr, and germinated on absorbent paper in covered plastic trays. Germination was in the dark at 25 C and 85c% relative humidity, and seedlings were harvested 84 hr after germination was begun. Growth rates of the seedlings were determined by marking at 2.5-mm intervals and subsequently measuring the spacings. Sequential epicotyl sections were taken from 0 to 5 mm, 6 to 10 mm, and 11 to 15 mm below the apical hook. The sections were either dropped into beakers on Dry Ice immediately after cutting in the case of samples for cell wall preparation by the nonaqueous method, or, in all other cases, they were weighed out in 0.5-g lots and then frozen on Dry Ice as soon as 0.5 g was obtained. The tissue was stored at -80 C until used.Cell Wall Preparation. Cell walls were prepared by homogenization in glycerol and filtration through a glass bead filter, as described by Kivilaan et al. (16). The wall material was dried in an evacuated dessicator over P205, CaCl2, and paraffin at 4 C for 24 to 48 hr. The resultant white powder was stored at -10 C in a sealed jar over CaSO4. Alternatively glycerol was removed from the pelleted walls by water, rather than by solvent washing, as in the Kivilaan procedure. Washing and collection by centrifugation was repeated three times, the cell wall material was collected by filtration, dried over P205 in vacuo, and stored as described above.Aqueous Cell Wall Preparation. Cell walls were also prepared by homogenization of 0.5-g aliquots of frozen tissue sections ground at 0 to 4 C in a 50-ml conical glass hom...

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“…Other variants in invertase expression have been described. Echeverria and Humphreys (8) (24), bean (28), tomato (4), Ricinus (3), oat (25), and maize (2,16). In maize, the Oh 43 invertase deficiency apparently prevents utilization of exogenous sucrose (27).…”

Section: Discussionmentioning

confidence: 99%

Organ-Specific Invertase Deficiency in the Primary Root of an Inbred Maize Line

Duke¹,

McCarty²,

Koch³

1991

Plant Physiol.

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An organ-specific invertase deficiency affecting only the primary root system is described in the Oh 43 inbred maize (Zea mays). Invertases (acid and neutral/soluble and insoluble) were assayed in various tissues of hybrid (NK 508) Sucrose breakdown is critical to the vast majority of plant species because nonphotosynthetic tissues depend on import ofthis sugar for their growth and development. Initial cleavage of sucrose can be catalyzed by either invertase (EC 3.2.1.26) or the reversible enzyme sucrose synthase (EC 2.4.1.13). Invertases are especially active in tissues undergoing rapid cell division, such as shoot and root apices (1). Previously, the role of invertases in sucrose transfer was considered particularly important in plants such as sugar cane and maize in which substantial sugar movement occurred through the cell wall space and was accompanied by action of an extracellular invertase (13,15). Recent evidence, however, indicates that, although much hydrolysis is often observed, invertase activity may not be essential for sucrose uptake into either sugar cane stems (21,31) or maize kernels (30).

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Exocellular Enzymes of Corn Roots

Cited by 88 publications

References 31 publications

Hydrolysis of organic phosphates by corn and soybean roots

Hydrolysis of organic phosphates by corn and soybean roots

Correlative Studies of Cell Wall Enzymes and Growth

Organ-Specific Invertase Deficiency in the Primary Root of an Inbred Maize Line

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