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?

Ethiopia goes for decaf

Reuters reports that Ethiopian coffee farmers will soon be able to grow a variety which is naturally low in caffeine. Details are sketchy. The whole thing seems to be based on the following statement by Mr Abera Deressa, State Minister of Agriculture and Rural Development, at an unnamed coffee research conference:

“Coffee research centres are in the process of planting seedlings of natural coffee with low caffeine varieties, to enable Ethiopia to supply the world market within the shortest possible time.”

The article mentions the 2004 controversy between the Ethiopian government and Brazilian researcher Paulo Mazzafera, who

declared he had discovered a variety of naturally decaffeinated coffee from 6,000 specimens collected in Ethiopia in the 1980s. The find sparked a dispute with Ethiopian authorities who accused him of taking the bushes without permission.

However, it is not clear whether the low-caffeine variety now being planted in research centres has anything to do with the one Mazzafera identified.

Decaffeinated coffee accounts for 10 percent of total coffee sales in the world, a multibillion-dollar industry. Natural decaf brews could dominate over the current chemically caffeine-reduced options in today’s health-conscious market.

The story has been picked up all over the place. It should run and run. Hopefully we’ll get some more details soon.

Wheats and gluten

Sometimes it takes some personal connection to get me motivated enough to try and understand something a little more fully. Laziness, I guess. Anyway, for example, I vaguely knew about the gluten seed storage proteins of wheat and the coeliac disease they cause in about 1% of the population. But I decided to delve a little deeper only when an old friend I hadn’t seen for a while visited today and told me that she was a sufferer, and that she needed to know how to describe the condition in italian so she wouldn’t get into trouble eating in restaurants here in Rome.

Having sorted that out, I was interested to know whether there are differences among wheat species in the “toxicity” of their glutens. You’ll remember that wheat comes in a polyploid series: diploid, tetraploids and hexaploids. And that three distinct genomes are involved: AA, BB and DD. Diploid einkorn (AA) and BB genome species got together to form tetraploid emmer and durum wheat (AABB). And these hybridized with wild diploid Triticum tauschii to make hexaploid (AABBDD) bread wheat.

It turns out that differences in gluten toxicity do exist. An analysis of the ancestral A, B and D genomes of wheat found that DNA sequences associated with 4 peptides that have been identified as triggering a response in coeliac patients are not distributed at random. For example, the B genome sequences analyzed did not reveal any of the “guilty” sequences.

On the basis of such insight, breeding strategies can be designed to generate less toxic varieties of wheat which may be tolerated by at least part of the [coelic disease] patient population.

Oh, and coeliac disease is called celiachia in italian.