Relation Between Acid Proteinase Activity and Redistribution of Nitrogen During Grain Development in Wheat

Dalling, MJ; Boland, G. J.; Wilson, JH

doi:10.1071/pp9760721

Cited by 120 publications

(78 citation statements)

References 26 publications

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“…Proteolysis during leaf senescence could be regulated by the appearance of new proteinases responsible for the hydrolysis of the leaf proteins in the same way that proteolysis in the storage tissues of young seedlings is regulated (1,2,8,9). Such a regulatory mechanism may exist in corn (5) and wheat (3,14) leaves where increases in proteinase activity accompany leaf senescence. Dalling et al (3) showed that there is a linear relationship between the acid proteinase activity measured with calculated rate of nitrogen loss from senescing wheat organs.…”

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confidence: 99%

“…Such a regulatory mechanism may exist in corn (5) and wheat (3,14) leaves where increases in proteinase activity accompany leaf senescence. Dalling et al (3) showed that there is a linear relationship between the acid proteinase activity measured with calculated rate of nitrogen loss from senescing wheat organs. Proteolysis could also be regulated by changing the accessibility of existing leaf proteases to leaf proteins.…”

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confidence: 99%

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Azocoll-digesting Proteinases in Soybean Leaves

Ragster

Chrispeels²

1979

Plant Physiol.

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Two different endopeptidases which digest the chromogenic substrate Azocoll were found in soybean leaves. Azocoilase A has a molecular weight of 17,500 and a pI of 6.0. Azocollase B has a molecular weight of 52,000 and a pl of 9.0. Both digest Azocoll optinally at pH 9.0. Azocollase A is inhibited by 3 milimlar ethylenediamine tetraacetate (EDTA) the characteristics of the proteinases, leaf age was not rigorously controlled. Young leaves are defined as those which have just expanded, mature (eaves are those which have been on the plant at least 2 weeks after reaching full size, and senescent leaves are those which show the first visible signs of yellowing. The leaves of greenhouse-grown plants were cut into small pieces and homogenized in a Polytron homogenizer (Kinematica, Luzerne, Switzerland) for 1 min at 3 C in 4 volumes of extraction medium. The extraction medium consisted of 50 mm K-phosphate (pH 7.5) with 1% insoluble PVP (Sigma) and 20 mM sodium metabisulfite.The leaves of field-grown plants were cooled to 3 C, transported to the laboratory in ice chests and processed immediately. Each sample was composed of the leaves from eight plants and four replicated samples were obtained and analyzed. Nodes 5 through 8 (see under "Results") represent the oldest leaves, whereas nodes 13 through 16 represent the youngest leaves on the same plant. The leaves were punched with a cork borer (9-mm diameter) and a known number of discs (200-300) were weighed. The weight of 100 leaf discs was relatively constant throughout the season, increasing about 10% from the 9th week to the 14th week, then dropping 20%1o in the 15th week. The weight of 100 leaf discs taken from leaves at the top of the canopy (nodes 13-16) was 5 to 10% greater than the weight of leaf discs taken from nodes 5 through 8. The leaf discs were frozen in liquid N2, and ground in a cold mortar and pestle. The resulting powder was mixed with 4 volumes of extraction medium containing 50 mm K-phosphate buffered at pH 7.5, 1% insoluble PVP, and 0.1% fB-mercaptoethanol. The homogenates were strained through cheesecloth, centrifuged for 10 min at 1,200g and the supernatant used as a source of enzyme.For studies which did not necessitate determinations of Chl and protein content of the leaves, homogenates were centrifuged at 857 www.plantphysiol.org on May 9, 2018 -Published by Downloaded from

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confidence: 99%

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confidence: 99%

Azocoll-digesting Proteinases in Soybean Leaves

Ragster

Chrispeels²

1979

Plant Physiol.

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“…The rate of nitrogen depletion from the vegetative parts of the plants is fairly constant as long as the nitrogen concentration in the tissue is above a threshold level of around 0.01 kg kg-1 (Dalling, Boland & Wilson, 1976). Such a constant rate of depletion can be explained as withdrawal from a pool of amino-acids that is maintained at a more or less constant level, when calculated on an integrated daily basis (Hanson & Ritz, 1983).…”

Section: Translocation Of Nitrogen To the Seedmentioning

confidence: 99%

“…As the concentration of nitrogen in the vegetative parts approaches the residual level the rate of depletion drops (Dalling et al, 1976). The rate of transfer from the vegetative tissue and the uptake rate by the seeds are both dependent on temperature with a Q10 value of around 2 (Vos, 1981).…”

Section: Translocation Of Nitrogen To the Seedmentioning

confidence: 99%

“…As the amino-acids are transferred from the vegetative tissue to the grain, storage or relatively stable proteins such as RuBPC-ase are mobilized, triggered by a rise in the level of proteolases at the onset of grain growth. The level ofproteolases stays relatively high during grain filling and drops only as the grain approaches maturity (Dalling et al, 1976).…”

Section: Translocation Of Nitrogen To the Seedmentioning

confidence: 99%

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Modelling the effects of nitrogen on canopy development and crop growth

Keulen¹,

Goudriaan

Seligman³

1989

Plant Canopies

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Nitrogen and Carbon Isotope Composition of Wheat Grain: Alteration due to Sink-source Modifications at Flowering

Hannachi

Deléens

Gate³

1996

Rapid Commun. Mass Spectrom.

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An experiment of sink-source modifications was performed in field-grown wheat at flowering on five varieties (four Triticum aestivum and one T. durum); among these, two varieties were non-awned. The sink-source modifications were blade removal (treatment B) and blade deletion and stalk and sheaths darkening (treatment C). Intact plants (treatment A) acted as a control. In the three awned varieties, the effect of awn removal was also analysed. Two lots of tests were initiaUy performed, with awns (treatments A+, B,, C,) or with awns removed (treatments A _ , B-, C-). Yields and carbon and nitrogen isotope compositions were then determined on seeds harvested at maturity. Blade deletion reduced the yield by one third whereas additional staIk and sheaths darkening led to a two thirds decrease. Nitrogen yield was similarly af€ected but the deprivation due to treatment C was less marked for nitrogen than for carbon. Thus, treatment C produced grains which were notably richer in nitrogen than plants which had received treatment A and B. For each of the five varieties, the decrease in yield was highly correlated with a I3C enrichment of grains (roughly from -28 to -25%). In contrast with the 13C variations, there was no general trend for ISN evolution among treated plants. The final yieId for treated T. durum plants was strongly modified when the awns were removed at flowering whereas no &@cant variations were noted in the other T aestivum awned varieties. Z durum seeds obtained from plants deprived of awns were notably depleted in ' C and in I5N compared to control plants. Isotope compositions of C and N of the Merent pools supplying the grain Wing were estimated and discussed in the context of the physiology of the mother plants between flowering and maturity.

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Relation Between Acid Proteinase Activity and Redistribution of Nitrogen During Grain Development in Wheat

Cited by 120 publications

References 26 publications

Azocoll-digesting Proteinases in Soybean Leaves

Azocoll-digesting Proteinases in Soybean Leaves

Modelling the effects of nitrogen on canopy development and crop growth

Nitrogen and Carbon Isotope Composition of Wheat Grain: Alteration due to Sink-source Modifications at Flowering

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