The media line on your cost sheet, and the swaps a review names

Tools of the trade

The line item you are actually looking at

The usual version of this decision: someone has asked for a lower cost per plantlet, and the agar invoice is the first thing on the desk that looks like a villain. Before you reformulate anything, it is worth knowing which costs the literature actually puts where, and which substitutes have been written up often enough to be worth a trial.

It is open access and the full review is on PubMed Central. Its subject is the obstacles facing plant tissue culture in Ethiopia and the lower-cost options available to labs working under budget constraints, and most of what it does is pull together figures and substitute lists from the published work it cites.

Where the cited figures put the cost

Those numbers come from different studies with different accounting, so do not stack them into a single pie chart. What they are useful for is proportion: if media is roughly a third of the cost of a plantlet in the work the review cites, then shaving a fraction off the gelling agent is a smaller lever than it feels like when you are signing the purchase order, and the energy and labor lines deserve the same scrutiny.

For context on the market the review is writing into, it cites Srivas and Sumant for a plant tissue culture market valued at USD 382.305 million in 2020 and projected to reach USD 895.006 million by 2030, a compound annual growth rate of 8.5 percent from 2021 to 2030.

What is on the substitution list

The review's own summary of replaceable items is short: gelling agents, macro and micronutrients, equipment, carbon sources, and the use of bioreactors, which it says can minimize space, energy and labor needs. The named substitutes, citing Naik et al. and others, break down like this.

That is a capital decision, not a media one, but it sits on the same cost sheet.

What the review does not hand you

It is a list of options, not a protocol. In the sections that name these substitutes, the review gives no concentrations, no vessel conditions and no species-by-species comparison of what each one did to multiplication or to plantlet quality. A starch gel result belongs to the study, species and genotype that produced it; it is not a rule that transfers to your crop because the ingredient is the same.

The review is also direct about the failure modes that already exist in conventional culture. It names high relative humidity inside the culture vessel causing hyperhydricity, and somaclonal variation, among the major disadvantages of plant tissue culture. A change in gelling agent changes the water relations in the vessel, which is exactly the territory those problems live in, so a swap needs its own trial rather than a straight substitution across your production line.

For buyers

Before you change the recipe

Keep a control batch on your current formulation running alongside anything new, change one component at a time, and decide in advance what you are counting: contamination at the next transfer, hyperhydric plantlets, multiplication rate, and losses at acclimation. A cheaper liter that costs you plantlets at hardening off is not cheaper. Whatever you use to record media batches, the batch number has to stay attached to the trays it produced all the way through acclimation, or the trial tells you nothing.

What the labs in the paper report

The review's survey of Ethiopian facilities is a useful reminder that scale decides which cost dominates.

The review attributes the pressure on labs partly to limited current expansion of the sugarcane program, alongside funding, infrastructure and staffing problems it lists elsewhere.

The call

If your question is where to look first, the review does not rank its substitutes by saving, and neither should you on its authority. The honest sequence is to price your own consumables per liter of made media, compare that against the energy and labor lines for the same output, and only then decide whether the gelling agent is where the money is for your operation. For a small lab making a few hundred liters a year, a cheaper gel may matter more than a bioreactor ever will; for a lab counting plantlets in the millions, the review's point about space, energy and labor is the one that scales.

When you do trial a substitute, treat it as a trial: one species, one genotype, a control, and a count that follows the batch to acclimation. And read the paper itself before you order anything, because the list above is the review's summary, not its detail. It is free to read in full on PubMed Central.