Vitamin C mystery solved, again

I blogged three months ago now about what was touted at the time as the final elucidation of the metabolic pathway by which plants make vitamin C. The piece in EurekAlert! which I quoted says:

UCLA and Dartmouth scientists have identified a crucial enzyme in plant vitamin C synthesis, which could lead to enhanced crops. The discovery now makes clear the entire 10-step process by which plants convert glucose into vitamin C, an important antioxidant in nature… It was not until 1998 that a biosynthetic pathway was proposed to explain how plants make this compound. Research confirmed much of the pathway, although one crucial missing link continued to baffle scientists and remained unknown until this new research.

So imagine my surprise when I read this today in FreshPlaza:

Agricultural scientists say they have uncovered the last big secret of vitamin C in plants, and it will create the chance to naturally breed healthier fruits. The breakthrough in understanding just how plants manufacture vitamin C will enable state science company Hortresearch to identify DNA markers for individual plants naturally producing high levels of the vitamin… Hortresearch’s science general manager, Dr Bruce Campbell said the team had isolated the last undiscovered enzyme and proved it controlled vitamin C in plants. The enzyme was the last step in a chain of research begun overseas nearly 80 years ago by scientist seeking to understand how plants produce vitamin C.

The research comes from New Zealand rather than the US, and was carried out on wild and cultivated kiwi fruit species with contrasting levels of vitamin C, rather than on Arabidopsis, but otherwise sounds as if it was aimed at solving pretty much the same problem. No way to tell from these brief summaries of the two pieces of work whether they came up with the same answer, though. That will take some more digging.

Anyway, it does seem likely that gene-jockeys will be falling over themselves all too soon trying to engineer a higher vitamin C apple, marula or whatever. Good luck to them. I’m no Luddite. But our friend Ola does have a point in his comment on my recent post on potatoes. Would it not maybe be easier and more cost effective to try to get people to eat foods which are naturally high in vitamin C?

Screening potatoes for micronutrients

Yet more about iron (and other assorted micronutrients). A recent post of mine elicited a comment from Glenn to the effect that breeders have screened germplasm collections of the major staples for micronutrient composition. I was skeptical about the extent to which this has been done (though not, I must add, about the fact that there will be much more of it in the future). Another post, this one by Jeremy, suggested that there was precious little information out there about variety-level nutritional information.

Well, I’ve now come across a paper that allows us to put some numbers on the amount of screening that has been done for one staple crop, the potato. There’s only an abstract freely available online, but a paper by CIP scientists reports (among other things) on micronutrient levels in native potato varieties in Peru:

Several studies have reported mineral concentrations in improved potatoes… However, limited information was available about the mineral concentration of potato germplasm and breeding materials until 2006. A detailed study was undertaken to determine the levels of Fe and Zn in 37 native varieties, both grown by farmers as well as from the collection under custody at CIP.

The potatoes were grown in a couple of different places. There was lots of variation, both genetic and due to the environment where they were grown, and also an interaction between these factors. And the heritability was high, suggesting that there is potential for improvement through selection and breeding.

But let’s remember that the total CIP potato collection amounts to over 7,500 accessions. That means that some 0.5% has been screened. A good start, but still only a start.

A famous Italian lentil

I spent the weekend in the Abruzzo region of Italy, which is kind of in the middle of the peninsula, both north-south and east-west. L’Aquila, the seat of the provincial government, is a couple of hours’ drive east of Rome. One of the places we visited was Santo Stefano di Sessanio, which is actually in the Gran Sasso National Park. It’s a pleasant enough medieval village, very well restored, though it has a whiff of Disneyland about it these days, especially in the summer.

Anyway, one of the many interesting things about this place is that it is famous for a particular kind of lentil — very small, tasty and apparently not needing to be soaked before cooking. And expensive. I don’t think the Lenticchia di Santo Stefano (photo below) has been protected like France’s Puy lentil, though.

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Incidentally, I came across that last link purely by coincidence today. I was going to talk about the Santo Stefano lentil anyway, but then a Google alert sent me to a posting in the Cookthink blog which mentions an article in The New Yorker about the place where I work, and refers back to the earlier piece about lentils.