Syntetisere klorofyll i mørket

Abstract

Plants undergo photosynthesis, one of the most important process on Earth. This happens through the help of chloroplasts, which uses sunlight, water and carbon dioxide to create oxygen. Oxygen is used by almost all forms of life in the process of respiration. Sugars are used by both other organisms as a source of energy, and by the plant itself during harsh conditions and periods with little sunlight. But in order for the process of photosynthesis to work, the chloroplast itself needs to be assembled.

This process requires a couple of enzymes to be in place and functional, the most important being protochlorophyllide oxidoreductase (POR) and chlorophyll synthase. These help with the last two steps of the chlorophyll synthesis.

In the present experiment, we investigated if the process of chlorophyll synthesis can be accomplished in conditions deprived of sunlight or any photon emitting sources. POR needs only a single photon to help phototransform protochlorophyllide (Pchlide) into chlorophyllide (Chlide) via NADPH, making it the only light-dependent step in the entire process. Although there are some plants that manage to accomplish this on their own e.g pine cones, usual flowering plants cannot.

The flowering plant used in this paper is barley, as it is easy to grow and cultivate, and does not require constant watering. Thus, this papers focus was trying to synthesize chlorophyll in the dark and in vitro, using barley plastid extracts. Data indicates that the conversion of Pchlide to Chlide via the Pchlide:POR:NADPH conjugate is not possible in the dark. There was a constant accumulation of the Pchlide:POR:NADPH conjugate, with no subsequent conversion and detectable trace of Chlide, both in vivo and in vitro. Although, after a quick 10 second burst of strong, white light to either samples, mass accumulation of Chlide could instantly be detected by the absorbance spectrophotometer. At the same time, biomolecular imaging indicated presence of chlorophyll a and b after exogenous GGPP addition to the phototransformed chlorophyllide.

These results could still have significant future implications when it comes to the amount of electricity used by plant cultivating greenhouses. If 10 seconds of white light was all it took for the light-dependent step to be completed, then plants could be grown in greenhouses. These sudden bursts of light at determined intervals, would decrease electrical cost and carbon footprint size in the long run, worldwide.

Plants undergo photosynthesis, one of the most important process on Earth. This happens through the help of chloroplasts, which uses sunlight, water and carbon dioxide to create oxygen. Oxygen is used by almost all forms of life in the process of respiration. Sugars are used by both other organisms as a source of energy, and by the plant itself during harsh conditions and periods with little sunlight. But in order for the process of photosynthesis to work, the chloroplast itself needs to be assembled.

This process requires a couple of enzymes to be in place and functional, the most important being protochlorophyllide oxidoreductase (POR) and chlorophyll synthase. These help with the last two steps of the chlorophyll synthesis.

In the present experiment, we investigated if the process of chlorophyll synthesis can be accomplished in conditions deprived of sunlight or any photon emitting sources. POR needs only a single photon to help phototransform protochlorophyllide (Pchlide) into chlorophyllide (Chlide) via NADPH, making it the only light-dependent step in the entire process. Although there are some plants that manage to accomplish this on their own e.g pine cones, usual flowering plants cannot.

The flowering plant used in this paper is barley, as it is easy to grow and cultivate, and does not require constant watering. Thus, this papers focus was trying to synthesize chlorophyll in the dark and in vitro, using barley plastid extracts. Data indicates that the conversion of Pchlide to Chlide via the Pchlide:POR:NADPH conjugate is not possible in the dark. There was a constant accumulation of the Pchlide:POR:NADPH conjugate, with no subsequent conversion and detectable trace of Chlide, both in vivo and in vitro. Although, after a quick 10 second burst of strong, white light to either samples, mass accumulation of Chlide could instantly be detected by the absorbance spectrophotometer. At the same time, biomolecular imaging indicated presence of chlorophyll a and b after exogenous GGPP addition to the phototransformed chlorophyllide.

These results could still have significant future implications when it comes to the amount of electricity used by plant cultivating greenhouses. If 10 seconds of white light was all it took for the light-dependent step to be completed, then plants could be grown in greenhouses. These sudden bursts of light at determined intervals, would decrease electrical cost and carbon footprint size in the long run, worldwide.