Abstract
Abstract The effects of red and far‐red light on the enhancement of in vitro nitrate reductase activity and on nitrate accumulation in etiolated excised maize leaves were examined. Illumination for 5 min with red light followed by a 4‐h dark period caused a marked increase in nitrate reductase activity, whereas a 5‐min illumination with far‐red light had no effect on the enzyme activity. The effect of red light was completely reversed by a subsequent illumination with the same period of far‐red light. Continuous far‐red light also enhanced nitrate reductase activity. Both photoreversibility by red and far‐red light and the operation of high intensity reaction under continuous far‐red light indicated that the induction of nitrate reductase was mediated by phytochrome. Though nitrate accumulation was slightly enhanced by red and continuous far‐red light treatments by 17% and 26% respectively, this is unlikely to account for the entire increase of nitrate reductase activity. The far‐red light treatments given in water, to leaves preincubated in nitrate, enhanced nitrate reductase activity considerably over the dark control. The presence of a lag phase and inhibition of increase in enzyme activity under continuous far‐red light‐by tungstate and inhibitors of RNA synthesis and protein synthesis‐rules out the possibility of activation of nitrate reductase and suggests de novo synthesis of the enzyme affected by phytochrome.
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Claims 9
Claim · model-written summary
Red light increased nitrate reductase activity after a dark period.
- Treatment
- Illumination for 5 min with red light followed by a 4‐h dark periode0
- Outcome
- nitrate reductase activitye0
- Direction
- increasee0
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Illumination for 5 min with red light followed by a 4‐h dark period caused a marked increase in nitrate reductase activity”
t0“maize leaves”
Claim · model-written summary
Five minutes of far-red light had no effect on nitrate reductase activity.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a 5‐min illumination with far‐red light had no effect on the enzyme activity”
t0“maize leaves”
Claim · model-written summary
Subsequent far-red illumination completely reversed the red-light effect.
- Treatment
- subsequent illumination with the same period of far‐red lighte0
- Outcome
- effect of red lighte0
- Direction
- completely reversede0
- Comparator
- red lighte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The effect of red light was completely reversed by a subsequent illumination with the same period of far‐red light”
t0“maize leaves”
Claim · model-written summary
Continuous far-red light enhanced nitrate reductase activity.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Continuous far‐red light also enhanced nitrate reductase activity”
t0“maize leaves”
Claim · model-written summary
Red light enhanced nitrate accumulation by 17%.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nitrate accumulation was slightly enhanced by red and continuous far‐red light treatments by 17% and 26% respectively”
t0“maize leaves”
Claim · model-written summary
Continuous far-red light enhanced nitrate accumulation by 26%.
- Treatment
- continuous far‐red light treatmentse0
- Outcome
- nitrate accumulatione0
- Direction
- enhancede0
- Value
- 26%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nitrate accumulation was slightly enhanced by red and continuous far‐red light treatments by 17% and 26% respectively”
t0“maize leaves”
Claim · model-written summary
Far-red treatment of nitrate-preincubated leaves increased nitrate reductase activity over dark control.
- Treatment
- far‐red light treatments given in watere0
- Outcome
- nitrate reductase activitye0
- Direction
- enhancede0
- Qualifier
- leaves preincubated in nitratee0
- Comparator
- dark controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“far‐red light treatments given in water, to leaves preincubated in nitrate, enhanced nitrate reductase activity considerably over the dark control”
t0“maize leaves”
Claim · model-written summary
Photoreversibility and high intensity far-red reaction indicated phytochrome-mediated nitrate reductase induction.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“photoreversibility by red and far‐red light and the operation of high intensity reaction under continuous far‐red light indicated that the induction of nitrate reductase was mediated by phytochrome”
t0“maize leaves”
Claim · model-written summary
Lag phase and inhibitor responses suggest de novo synthesis of nitrate reductase affected by phytochrome.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The presence of a lag phase and inhibition of increase in enzyme activity under continuous far‐red light‐by tungstate and inhibitors of RNA synthesis and protein synthesis‐rules out the possibility of activation of nitrate reductase and suggests de novo synthesis of the enzyme affected by phytochrome”
t0“maize leaves”
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