Article

Regulation of Photosynthetic Induction State in High- and Low-Light-Grown Soybean and Alocasia macrorrhiza (L.) G. Don.

Section of Plant Biology, University of California, Davis, California 95616-8537.
Plant physiology (Impact Factor: 6.56). 10/1995; 109(1):307-317.
Source: PubMed

ABSTRACT Alocasia (Alocasia macrorrhiza [L.] G. Don) and soybean (Glycine max [L.]) were grown under high or low photon flux density (PFD) conditions to achieve a range of photosynthetic capacities and light-adaptation modes. The CO2 assimilation rate and in vivo linear electron transport rate (Jf) were determined over a range of PFDs and under saturating 1-s-duration lightflecks applied at a range of frequencies. At the same mean PFD, the assimilation rate and the Jf were lower under the lightfleck regimes than under constant light. The activation state of two, key enzymes of the photosynthetic carbon reduction cycle pathway, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and fructose-1,6-bisphosphatase, and the photosynthetic induction states (ISs) were also found to be lower under flashing as compared to continuous PFD. Under all conditions, the IS measured 120 s after an increase in PFD to constant and saturating values was highly correlated with the Rubisco activation state and stomatal conductances established in the light regime before the increase. Both the fructose-1,6-bisphosphatase and Rubisco activities established in a particular light regime were highly correlated with the mean Jf in that regime. The relationships between enzyme activation state and Jf and between IS and enzyme activation state were similar in soybean and Alocasia and were not affected either by growth-light regime, and hence photosynthetic capacity, or by flashing versus constant PFD. The common relationship between the linear Jf and the activation state of key enzymes suggests that electron transport may be the determinant of the signal regulating IS, at least to the extent that the IS is controlled by the activation state of key stromal enzymes.

0 Bookmarks
 · 
59 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Photosynthetic induction responses to abrupt increases in photon flux density (PFD) to 800 and 1500 &mgr;mol m(-2) s(-1) from either darkness or 100 &mgr;mol m(-2) s(-1) were examined in situ in leaves of Fagus crenata Blume, Daphniphyllum humile Maxim., and Acer rufinerve Siebold & Zucc. growing in a gap and the understory of an F. crenata forest. Among the species studied, F. crenata exhibited the highest assimilation rate (A(100)), stomatal conductance (g(s100)) at the background PFD of 100 &mgr;mol m(-2) s(-1), and A(100)/A(max) (A(max) = maximum assimilation rate), in both the gap and the understory. Time required for full induction depended on both background PFD and maximum PFD. The induction period was 2-4-fold shorter at a background PFD of 100 &mgr;mol m(-2) s(-1) than in darkness. For the three understory species, time required to full induction was 2-3-fold longer when irradiance was increased from darkness to 800 &mgr;mol m(-2) s(-1) than when irradiance was increased from darkness to 1500 &mgr;mol m(-2) s(-1). Acer rufinerve showed higher initial stomatal conductance (g(s0)) and a shorter induction period in the understory than in the gap. Fagus crenata exhibited a similar g(s0) and induction period in both habitats. Daphniphyllum humile demonstrated lower g(s0) and a longer induction period in the understory than in the gap. These findings indicate that initial stomatal conductance is closely correlated with the photosynthetic induction response. We conclude that the photosynthetic induction response is affected by the light conditions experienced by plants before the sudden increase in irradiance and by the extent of the increase in irradiance.
    Tree Physiology 08/1999; 19(10):625-634. · 2.85 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The effect of a short-term increase in growth irradiance (I) by 1.5–5 times on the rate of the photosynthetic electron transport and the activity of ferredoxin-NADP+oxidoreductase (FNR) in the leaves of broadbean (Vicia fabaL.) plants grown under an irradiance of 8 W/m2was studied. NADPH-diaphorase and cytochrome creductase activities of FNR were determined in isolated chloroplasts and leaf homogenates. The duration of the plant exposure to a higher I varied from 1–30 min to 2 or 24 h. The rate of noncyclic electron transport from water to NADP+and the NADPH-diaphorase activity of FNR increased significantly 15 min after a twofold increase in the I. FNR activation was also found after a short-term (1 min) increase in growth I by 1.5 times. The degree of light-induced activation of FNR was dependent on the light intensity, the duration of plant exposure, and the leaf age. The activation of FNR induced by a short-term increase in the I was reversible. However, inactivation of FNR proceeded more slowly than its light-induced activation. Thus, a relatively small change in the I was sufficient to induce the adaptive response of the photosynthetic apparatus at the level of the electron-transport chain. The results obtained confirm a conclusion made previously that a rapid activation of FNR induced by an increase in the I occurs in the absence of de novoprotein synthesis.
    Russian Journal of Plant Physiology 08/2001; 48(5):601-607. · 0.62 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: ABSTRACTA dynamic model of leaf photosynthesis for C3 plants has been developed for examination of the role of the dynamic properties of the photosynthetic apparatus in regulating CO2 assimilation in variable light regimes. The model is modified from the Farquhar-von Caemmerer-Berry model by explicitly including metabolite pools and the effects of light activation and deactivation of Calvin cycle enzymes. It is coupled to a dynamic stomatal conductance model, with the assimilation rate at any time being determined by the joint effects of the dynamic biochemical model and the stomatal conductance model on the intercellular CO2 pressure. When parametrized for each species, the model was shown to exhibit responses to step changes in photon flux density that agreed closely with the observed responses for both the understory plant Alocasia macrorrhiza and the crop plant Glycine max. Comparisons of measured and simulated photosynthesis under simulated light regimes having natural patterns of lightfleck frequencies and durations showed that the simulated total for Alocasia was within ±4% of the measured total assimilation, but that both were 12–50% less than the predictions from a steady–state solution of the model. Agreement was within ±10% for Glycine max, and only small differences were apparent between the dynamic and steady–state predictions. The model may therefore be parametrized for quite different species, and is shown to reflect more accurately the dynamics of photosynthesis than earlier dynamic models.
    Plant Cell and Environment 06/2008; 20(4):411 - 424. · 5.91 Impact Factor

Full-text (2 Sources)

View
19 Downloads
Available from
May 21, 2014