Increased Cytokinin from Root System of Perilla frutescens and Flower and Fruit Development

Beever, Jessica E.; Woolhouse, H. W.

doi:10.1038/newbio246031a0

Cited by 33 publications

(11 citation statements)

References 19 publications

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“…Beever and Woolhouse (1973) reported a marked fall in cytokinin flux in the xylem of Perilla frutescens during flower and fruit development. Since the presence of cytokinins is known to delay senescence (Richmond and Lang 1957;Fletcher 1969), a fall in cytokinin level might be expected to promote senescence, presumably by inducing increased proteinase activity.…”

Section: Discussionmentioning

confidence: 99%

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

Dalling¹,

Boland²,

Wilson³

1976

Functional Plant Biol.

120

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Accumulation of grain nitrogen was studied in the wheat cultivars Argentine IX and Insignia. The pattern of nitrogen removal from several tissues of each cultivar was compared with the pattern of acid proteinase activity. There was a highly significant relation between the rate of nitrogen loss from the tissues and the rate estimated from the enzyme activity measurements. This suggests an important role for acid proteinase enzymes in leaf senescence. Redistribution of nitrogen present in the plant at anthesis accounted for 78.5 and 80.6 % of the final grain nitrogen yield of Argentine IX and Insignia respectively.

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Section: Discussionmentioning

confidence: 99%

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

Dalling¹,

Boland²,

Wilson³

1976

Functional Plant Biol.

120

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“…Seasonal variations of cytokinin-like activity in root pressure exudate have been reported in a number of genera (2, 3, 7-9, 22, 24). In Perilla, there was a 5-fold increase in cytokinin-like activity in root pressure exudate after floral induction (2,3). Conversely, the root sap of Xanthium plants which had been induced to flower contained less than onethird as much cytokinin-like activity as did the sap of vegetative plants (24).…”

Section: Grpahymentioning

confidence: 99%

Ontogenetic Variation of Four Cytokinins in Soybean Root Pressure Exudate

Heindl

Carlson²,

Brun³

et al. 1982

Plant Physiol.

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No correlation was found between cytokinin fluxes and nodule dry weight or specific nodule activity (acetylene reduction).The timing of distinct peaks in zeatin riboside and dihydrozeatin riboside fluxes during flowering or pod formation suggests that cytokinins exported from the root may function in the regulation of reproductive growth in soybean.The roles of cytokinins in plant growth and development are not fully understood, but evidence supports the hypothesis that cytokinins are produced by the root system and transported to the shoot, where they are involved in the regulation of shoot processes (3,22,27). Transport in the xylem sap of materials with cytokininlike activity (determined by bioassay) has been demonstrated in numerous species including sunflower (22), tomato (7), and lupin (8, 9). Cytokinin-like materials have also been reported in the root nodules of Viciafaba (13) nodules, they detected Z2 and a number ofits metabolites throughout the plant.If cytokinins from the root system are involved in regulating shoot growth and function, then their supply to the shoot should fluctuate over the course of development. Seasonal variations of cytokinin-like activity in root pressure exudate have been reported in a number of genera (2, 3, 7-9, 22, 24). In Perilla, there was a 5-fold increase in cytokinin-like activity in root pressure exudate after floral induction (2, 3). Conversely, the root sap of Xanthium plants which had been induced to flower contained less than onethird as much cytokinin-like activity as did the sap of vegetative plants (24).Although cytokinins were not specifically identified as the active regulating component, several studies have shown that roots or factors from the roots are required for maintaining leaf Chl content (18) and photosynthesis (4,5,18,27). In Phaseolus, foliar applications of BA delayed Chl loss and photosynthetic decline associated with senescence (1).In A. glutinosa, cytokinin-like activity in the root nodules increased prior to the onset of nitrogenase activity (acetylene reduction) and declined by the time N2-fixing capacity had been fully established (14). Likewise, Newcomb et al. demonstrated that cytokinin-like activity in pea nodules was greatest early in nodule development and decreased thereafter (20). Henson and Wheeler hypothesized that cytokinins exported from nodules affected N2-fixation through either local action in the nodule or by a remote effect on the shoot (14).Presence of cytokinins in soybean root pressure exudate has not been demonstrated. Therefore, it was not known whether or not these hormones could be involved in the regulation of soybean development. Hence, the objectives of our research were to (a) establish the presence of cytokinins and (b) describe profiles of cytokinin flux in root pressure exudate in relation to the ontogeny of soybean plants grown in the field and in growth chambers. Root pressure exudate was collected and acetylene reduction activity was measured from late in vegetative growth through maturity. Four cytokinin...

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“…There is a good deal of evidence which indicates that cytokinin-like substances produced by roots may regulate senescence of leaves in intact plants (7,16). Available reports suggest that a rise in ABA (4,11) and a depletion of cytokinin in leaves (2,7,18) during advanced stages of reproductive development might be the prime factors in the control of monocarpic senescence of a number of plants at the hormonal level. Early work (13) strongly supported the concept ofmobilization ofnutrients as the cause ofmonocarpic senescence, though it has been questioned by several workers (6,(9)(10)15).…”

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confidence: 99%

Mobilization of Metabolites from Leaves to Grains as the Cause of Monocarpic Senescence in Rice

Ray¹,

Choudhuri²

1981

Plant Physiol.

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The pattern of senescence was studied by following the changes in chlorophyll and protein in the leaVes and by measuring 32P retention and export from source to sink during development of the rice plant (O'yza satva L. cv. Jaya) subjected to different manipulative treatments. With the advance of reproductive development, the chronologcal sequence of leaf senescence was changed, so that the flag and the third leaf senesced earlier than did the second leaf. In presence of the daughter shoot of defruited plants, senescence was delayed in all three leaves of the mother plant, as compared to the same leaves of intact plants. Senescence of all three leaves was further delayed when both panicle and daughter shoots were removed from the plant. The above manipulative treatments caused the initial sequential pattern of senescence of leaves to persist. Removal of both panicle and daughter shoots caused little export of 32p between leaves. In the presence of daughter shoots of defruited plants, export of "2p was maximum from leaves of the mother plant to the nearest daughter shoots. This led to earlier senescence of such mother plant leaves than that of plants from which both panicle and daughter shoots were removed. The pattern of senescence and export of asp in the flag and the second leaf of the daughter shoot was essentially the same as that of the intact plant.Based on these finigs, it was concluded that mobilzation of metabolites from source to sink is the primary cause of monocarpic senescence in rice.Although much attention has been paid to whole plant senescence in recent years (6-10, 15, 17), neither the mechanism nor the physiological basis for this phenomenon is clearly understood (14). Previous reports from this laboratory pointed out that, in monocarpic rice plants, mobilization of metabolites from leaves to grains results in a deprivation stress in leaves, followed by an increased ABA accumulation, leading to senescence (4). There is a good deal of evidence which indicates that cytokinin-like substances produced by roots may regulate senescence of leaves in intact plants (7,16). Available reports suggest that a rise in ABA (4, 11) and a depletion of cytokinin in leaves (2, 7, 18) during advanced stages of reproductive development might be the prime factors in the control of monocarpic senescence of a number of plants at the hormonal level. Early work (13) strongly supported the concept ofmobilization ofnutrients as the cause ofmonocarpic senescence, though it has been questioned by several workers (6, 9-10, 15). The present study provides further evidence in support of the hypothesis that mobilization of metabolites from source to sink is the primary cause of the onset of senescence in monocarpic rice plants.MATERIALS AND METHODS Cultivation of Plants. Certified seeds (having 100%o germinability) of rice (Oryza sativa L. cv. Jaya) were collected from the Crop Research Farm, University of Burdwan, Burdwan, India. These were surface-sterilized in 0.1% HgCl2 for 1 min and then washed well in distilled H2...

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Increased Cytokinin from Root System of Perilla frutescens and Flower and Fruit Development

Cited by 33 publications

References 19 publications

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

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

Ontogenetic Variation of Four Cytokinins in Soybean Root Pressure Exudate

Mobilization of Metabolites from Leaves to Grains as the Cause of Monocarpic Senescence in Rice

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