Adaption to Photosynthesis and Diurnal Oscillation of Root Respiration Rates for <i>Lolium multiflorum</i>

Hansen, G. K.

doi:10.1111/j.1399-3054.1977.tb01883.x

Cited by 56 publications

(32 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…5). These results involving excised root tips explain the observations made on intact plants showing variations of the root respiratory rate linked to various treatments affecting either synthesis or translocation of photosynthates (6,9).…”

Section: Methodssupporting

confidence: 67%

“…Stimulation of root respiratory rate by light after darkness has been reported previously (6,9). Hatrick and Bowling (10), using sunflower and barley, reported evidence for a complete dependence of root respiration on the rate of assimilate translocation from the shoot, suggesting that roots of young herbaceous plants have no reserves which might reduce the effect of fluctuations in the rate of translocation of photosynthetic sugars.…”

mentioning

confidence: 90%

See 1 more Smart Citation

Soluble Sugars, Respiration, and Energy Charge during Aging of Excised Maize Root Tips

Saglio¹,

Pradet²

1980

Plant Physiol.

206

123

View full text Add to dashboard Cite

Oxygen uptake and energy charge were monitored during aging of excised maize root tips and related to the soluble sugar content and exogenous sugar supply.Oxygen uptake declined imsediately after excision to 50 to 30% of its initial value after 8 and 24 hours of aging at 25 C. There was also a sharp decline of the total sugar content (glucose, fructose, and sucrose). Starch content was very low at the time of excision and aimost neglgible 5 hours later. During the same period, the respiratory quotient declined from I to 0.75 and then remained stable.The addition of exogenous sugars induced a rapid rise of the respiratory rate which stabilized at a level correlated to the external sugar concentration. Addition of 0.2 molar glucose was necessary to restore the respiratory rate to the initial, also the maximum, level. These results indicate that metabolic activity of root tips is hily reliant on sugar import and carbohydrate reserves at the time of excision cannot compensate for the cessation of import. The control of respiration by substrate supply is in good agreement with the failure for dinitrophenol to stimulate oxygen uptake in aged sugar-depleted root tips.The energy charge remained constant at about 0.9, irrespective of the presence or absence of glucose and in spite of a large decline of respiratory activity in aged, sugar-depleted tissues.In normoxia as defined by Pradet and Bomsel (16), the respiratory rate of tissues is not limited by the 02 partial pressure.Under such conditions, most of the biological energy provided to the cells comes from sugar oxidation through respiratory pathways. The sugar supply of non-chlorophyllous tissues varies depending upon factors which affect the efficiency ofcarbon fixation by leaves and transport of the recently synthesized carbohydrates (5, 7, 13, 21).The question arises as to how metabolism adjusts to such fluctuation. Stimulation of root respiratory rate by light after darkness has been reported previously (6, 9). Hatrick and Bowling (10), using sunflower and barley, reported evidence for a complete dependence of root respiration on the rate of assimilate translocation from the shoot, suggesting that roots of young herbaceous plants have no reserves which might reduce the effect of fluctuations in the rate of translocation of photosynthetic sugars.The present study is part of an effort to understand the factors which limit and control the metabolic activity of roots. Our approach was to relate 02 uptake, taken as a measure of the metabolic activity, to soluble sugar and adenine nucleotide content of the tissues at various times after excision. The data reported demonstrate the influence of exogenous sugars on the metabolic activity of root tips. The significance ofenergy charge as parameter of normoxic cellular metabolism is discussed. MATERIALS AND METHODSPrimary root tips, 0.5 cm, were cut from maize seedlings (Zea mays L. INRA 402) germinated for 3 days at 25 C between sheets of filter paper soaked with 2 mm CaCl2.Determination of Gas Exchange. Measureme...

show abstract

Section: Methodssupporting

confidence: 67%

mentioning

confidence: 90%

Soluble Sugars, Respiration, and Energy Charge during Aging of Excised Maize Root Tips

Saglio¹,

Pradet²

1980

Plant Physiol.

206

123

View full text Add to dashboard Cite

show abstract

“…This question is relevant to understanding the responses of roots to changes in temperature and our simulation suggests that root and shoot activity might be very tightly coupled during the growing season. It seems clear that in some herbaceous plants, photosynthesis and root respiration are directly coupled on time scales that range from minutes to hours (Hansen, 1977 ;Massimino et al, 1981 ;Ryle et al, 1985 ;Amthor, 1994). After reviewing work with annual plants and conducting experiments with single-rooted soybean leaves, Farrar & Jones (2000) argue that C allocation to roots is controlled jointly by roots and shoots.…”

Section: - - mentioning

confidence: 99%

Responses of tree fine roots to temperature

et al. 2000

View full text Add to dashboard Cite

Soil temperature can influence the functioning of roots in many ways. If soil moisture and nutrient availability are adequate, rates of root length extension and root mortality increase with increasing soil temperature, at least up to an optimal temperature for root growth, which seems to vary among taxa. Root growth and root mortality are highly seasonal in perennial plants, with a flush of growth in spring and significant mortality in the fall. At present we do not understand whether root growth phenology responds to the same temperature cues that are known to control shoot growth. We also do not understand whether the flush of root growth in the spring depends on the utilization of stored nonstructural carbohydrates, or if it is fueled by current photosynthate. Root respiration increases exponentially with temperature, but Q "! values range widely from c. 1.5 to 3.0. Significant questions yet to be resolved are : whether rates of root respiration acclimate to soil temperature, and what mechanisms control acclimation if it occurs. Limited data suggest that fine roots depend heavily on the import of new carbon (C) from the canopy during the growing season. We hypothesize that root growth and root respiration are tightly linked to whole-canopy assimilation through complex source-sink relationships within the plant. Our understanding of how the whole plant responds to dynamic changes in soil temperature, moisture and nutrient availability is poor, even though it is well known that multiple growth-limiting resources change simultaneously through time during a typical growing season. We review the interactions between soil temperature and other growth-limiting factors to illustrate how simple generalizations about temperature and root functioning can be misleading.

show abstract

“…3). The persistence of a 12-h rhythm over upon photoperiodically-induced processes rather than upon other a wide-ranging light period within a 24-h photoperiod has also fluctuating environmental factors is demonstrated by the 6-h shift been observed in respiration of Lolium multqflorum (13). Lolium in rhythm that occurred with a 6-h shift in the light:dark regimen roots displayed diurnal fluctuations with two peaks separated by (Fig.…”

Section: Discussionmentioning

confidence: 98%

Rhythms in Glutamine Synthetase Activity, Energy Charge, and Glutamine in Sunflower Roots

Knight

Weissman²

1982

Plant Physiol.

View full text Add to dashboard Cite

Roots of sunflower plants (Helianthus anus L. var. Mammoth Russian) subjected to ,12:D12, L18:D6, and L12:D12 followed by continuous light all display rhythms of about 12 hours for glutamine synthetase (GS) activity (transferase reaction) with one peak in the 'light phase' and one in the 'dark phase.' Root energy charge (EC = ATP+%ADP/ ATP+ADP+AMP) is directly correlated with GS, but the GS rhythm is better explained as the result of a rhythmic adenine nucleotide ratio (ATP/ ADP+AMP) that regulates enzyme activity through allosteric modification. When L12:D12 plants are subjected to free-running conditions in continuous darkness, only diurnal rhythms for GS and EC, with peaks in the dark phase, remain. The 12-hour root rhythms for GS and EC appear to be composed of two alternating rhythms, one a diurnal, light-dependent, incompletely circadian light phase rhythm and the other a light-independent, circadian dark phase rhythm.Only glutamine, of the root amino acids, displays cyclical changes in concentration, maintaining under all conditions a 12-hour rhythm that is consistently synchronized with, but nearly always inversely correlated with, GS and EC rhythms.The phenomenon of endogenous biological oscillation in plants has been found to occur at all levels of organization: organ, cells, organelle, and enzyme (7). Almost universally, the light:dark regimen has been identified as the entraining factor and numerous examples of light-entrainable rhythms have been reported for physiological or biochemical processes in higher plants (14). Most rhythms appear to be circadian with periodicities under freerunning conditions ofapproximately 24 h. Also reported, however, are rhythms with a period clearly less than 24 h and these have been termed 'ultradian' (10). In view of the correlation demonstrated in this laboratory (34) between the activity of sunflower root GS3 and energy charge as defined by Atkinson (2) investigation in which an effort has been made to determine whether energy charge and GS vary in a cyclical manner in sunflower roots, a portion of the plant not expected to be directly affected by light functioning as a 'Zeitgeber.' In view of the fact that previous studies have indicated a role for amino acids in the regulation of higher plant GS (22, 27), we have also examined variations in the concentrations of these substances in sunflower roots with respect to rhythmicity. MATERIALS AND METHODSPlant Culture. Sunflower seeds (Helianthus annus L. var. Mammoth Russian) were germinated in vermiculite in a controlled temperature chamber (26-27°C) under artificial light with a light:dark regimen specific to a particular experiment (L12:D12, L18:D6). Eight-d-old seedlings were transferred to a previously described (35) continuous flow apparatus that provided enclosure of the root system in blackened tubes. Complete culture solution containing nitrogen as 10 mm NO3 was allowed to pass over the roots for the remainder of the growth period. On day 28, the plants, having previously been subjected to a specific l...

show abstract

Adaption to Photosynthesis and Diurnal Oscillation of Root Respiration Rates for Lolium multiflorum

Cited by 56 publications

References 10 publications

Soluble Sugars, Respiration, and Energy Charge during Aging of Excised Maize Root Tips

Soluble Sugars, Respiration, and Energy Charge during Aging of Excised Maize Root Tips

Responses of tree fine roots to temperature

Rhythms in Glutamine Synthetase Activity, Energy Charge, and Glutamine in Sunflower Roots

Contact Info

Product

Resources

About