How Do Plants Make Chlorophyll in the Dark?

As an Amazon Associate we earn from qualifying purchases.

How do plants make chlorophyll in the dark? Only up to a point. Research on dark-grown plants shows that the early chain of steps runs without light, while the final conversion needs it. The chain starts in darkness, stalls at an intermediate called protochlorophyllide, and then moves forward once light arrives. This article explains that mechanism using three research sources and separates what those sources state from what they leave open. For related plant timing, see how plants sense day length and how seeds sense light before germinating.

Quick answer

• The early steps run in darkness. Research states that “protochlorophyllide, the chlorophyll precursor is synthesized in the darkness”.
• The final conversion needs light. The enzymes involved are described as “unique enzymes directly activated by light”.
• The intermediate waits in the leaf. Dark-grown leaves hold the precursor until light arrives.
• The molecular change is very fast. Conversion is “taking place in order of ns to µs after seedlings illumination”.

How we chose

This article uses the three sources named at the end. Two are older Plant Physiology papers available only as abstracts, and one is a 2023 full research article from Frontiers in Plant Science. Every factual sentence below is tied to a quote from one of these sources.

Why darkness does not stop the whole pathway

Chlorophyll is built through a long chain of small steps, and the early part of that chain does not depend on light. The 2023 research article states that “protochlorophyllide, the chlorophyll precursor is synthesized in the darkness from the L-Glutamate and tRNA Glu leading (through number of steps) to formation of 5-aminolevulonic acid (ALA), the universal precursor for all tetrapyrroles”. So the pathway can run well before any sunlight reaches the plant.

The earlier work on dark-grown plants points the same way. The 1971 bean study reports that “Dark-grown leaves placed in solutions of δ-aminolevulinic acid accumulate protochlorophyllide 632”. When the starting material is supplied, dark-grown leaves keep building the intermediate even though no light is present.

The stalled intermediate

The pathway does not finish in the dark. The 1971 study describes two forms of the intermediate and identifies one of them as “directly photoconvertible to chlorophyllide”. The word “photoconvertible” is the key point: the molecule is ready to be changed by light, but the change requires light to happen.

The 2023 article describes how the stored precursor is held. The enzymes “form a complex with dark-synthesized protochlorophyllide and NADPH and oligomerize, leading to formation of paracrystalline structures in the etioplast membranes called prolamellar bodies”. The article identifies these etioplast structures as the place where the stored precursor sits before light arrives.

What light does at the final step

Light is the trigger for the conversion. The 2023 article describes the change as “the result of photocatalysis mediated by light-dependent PORs, unique enzymes directly activated by light”. The protochlorophyllide inside the enzyme complex does two jobs. The article states that “the protochlorophyllide in the complex acts as both the substrate and the light-sensing chromophore, initiating its own C17-C18 double bond reduction in the active site of PORs”. The molecule that is changed is also the molecule that absorbs the light that changes it.

Timing is measured in very short steps at the start. The article reports that “The conversion of dark accumulated protochlorophyllide to chlorophyll in etioplasts of de-etiolating plants is taking place in order of ns to µs after seedlings illumination, leading to detectable increase of chlorophyll levels in order of minutes after de-etiolation initiation”. So the molecular change happens within nanoseconds to microseconds, while the rise in chlorophyll that can be detected takes minutes.

How light changes the seedling over time

Light does more than convert one molecule. The 2023 article describes de-etiolation as a larger program: “Light is the main trigger of de-etiolation, associated with inhibition of hypocotyl elongation, expansion and unfolding of the cotyledons and synthesis of individual components of the photosynthetic apparatus and photoprotective pigments”. The conversion of the stored precursor is one part of that wider switch.

The timing also matters because intermediates can cause damage. The article states that “during de-etiolation, the plants must solve a problem of balancing the chlorophyll biosynthesis and assembly of the light-harvesting complexes, as the chlorophyll biosynthesis intermediates and the free chlorophyll itself can lead to harmful singlet oxygen formation due to photooxidation”. A seedling that is exposed to light too early or too late faces that balancing problem.

The 1975 maize study adds a point about control. It reports that “the accumulation of protochlorophyll upon transfer to darkness in the absence of levulinic acid stops much earlier”. The authors suggest that “a control point exists in the pathway between ALA and protochlorophyll, preventing utilization of the accumulated ALA upon transfer of greening leaves to darkness”. In plain terms, the pathway has a regulated point in the dark, not an unlimited supply line.

The same 1975 study reports a rate for the early enzyme system. It states that “The system synthesizing ALA decays in the dark with a half-life of about 80 minutes”. That figure comes from one maize leaf system under the conditions the authors tested, so it describes that system, not plants in general.

What this means for a plant grown in the dark

A plant kept in darkness can make the early precursor, and it can hold the intermediate. What it cannot do, according to the sources, is complete the final step without light. The 2023 article describes that final step as one that is “directly activated by light”. Once light reaches the leaves, the stored intermediate is converted quickly, and the rest of the greening program follows.

This is a mechanism, not a growing method. The sources explain why a dark-grown plant holds an intermediate, but they do not give instructions for how deep to plant seeds or how long a seedling should stay covered. Those questions are outside what the three sources cover.

What we could not verify

The two older papers available to this article are represented by their abstracts, not full text. The 1971 bean study and the 1975 maize study were both published before modern molecular methods, and their PDF files did not return readable article text when checked. Claims from those papers are limited to what their abstracts state. The 2023 article is a full research article, but it is a single study of Arabidopsis seedlings, not a survey of all plants.

What the sources do not say

The sources do not give a time to full green for any specific species, and this article does not state one. They also do not compare the dark pathway across plant groups. None of the three sources gives planting or covering advice, so this article does not add any.

Frequently asked questions

Can a plant make chlorophyll with no light at all?

It can make the early precursor in darkness. The 2023 article states that “protochlorophyllide, the chlorophyll precursor is synthesized in the darkness”. The final conversion to chlorophyll needs light, so the sources do not describe full chlorophyll forming in complete darkness.

What is protochlorophyllide?

It is the intermediate that sits just before chlorophyll in the pathway. The 1971 study identifies one form as “directly photoconvertible to chlorophyllide”, meaning light can change it directly.

Why do dark-grown seedlings hold this intermediate?

The stored intermediate waits for light to be converted. The 2023 article describes the stored state as prolamellar bodies in etioplast membranes, where the enzymes sit with the dark-made precursor.

How fast does greening start after light arrives?

The molecular conversion is very fast. The 2023 article reports conversion “in order of ns to µs after seedlings illumination”, while the rise in chlorophyll that can be detected takes minutes.

Does every plant need light for this last step?

The sources describe a light-triggered final step in the enzyme family they studied. They do not establish that every plant group works the same way, so this article does not make a general claim beyond the organisms studied.

Sources

• Murray AE, Klein AO. “Relationship between Photoconvertible and Nonphotoconvertible Protochlorophyllides.” Plant Physiology, 1971. https://pmc.ncbi.nlm.nih.gov/articles/PMC396872/ (opened 2026-10-28, HTTP 200)
• Fluhr R, Harel E, Klein S, Meller E. “Control of δ-Aminolevulinic Acid and Chlorophyll Accumulation in Greening Maize Leaves upon Light-Dark Transitions.” Plant Physiology, 1975. https://pmc.ncbi.nlm.nih.gov/articles/PMC541856/ (opened 2026-10-28, HTTP 200)
• De-etiolation and chlorophyll biosynthesis research article, Frontiers in Plant Science, 2023. https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.1093292/xml (opened 2026-10-28, HTTP 200)