Boring boron resistance gene found in barley.
Carolina Gold
In the early 1700’s, rice was South Carolina’s main export — no wonder the variety grown was called Carolina Gold. But where did it come from?
The first reported import in the New World of what is thought to be Carolina Gold occurred in 1685, when a slave ship from Madagascar unloaded a cargo of rice in Charleston, South Carolina.
So was that Indian Ocean island the ultimate source of Carolina Gold? USDA geneticists think they know, and have written about it in a new paper. Anna McClung and Robert Fjellstrom looked for molecular markers for Carolina Gold among the material in USDA rice germplasm collection. The best genetic fit — confirmed by close morphological similarity — was actually with an accession from Ghana, not Madagascar.
Questions remain. Maybe material from Carolina — originally derived from somewhere else — found its way back to Africa.
But geographer Judith Carney of the University of California, Los Angeles, says a Ghanaian origin of Carolina Gold fits with the idea that Carolina Gold arrived in the colony as food on slave ships and was then planted by the slaves.
Efforts are underway to bring this historical variety back into commercial cultivation.
Potato taxonomy
Quick quiz: How many species of cultivated potatoes are there?
Garlic; cooking and diversity
How to cook garlic. Oh, and also how to identify duplicates in garlic germplasm collections by DNA fingerprinting.
Hot or not? A SNP provides the answer
Time was when you tested how hot a chilli pepper was by tasting a teeny bit with your tongue, at least if you were brave. The hotter it tasted, the more capsaicin it contained, and the hotter it was. Then came Wilbur Scoville and his eponymous scale. 1 Now, all you need is a well-equipped molecular biology laboratory.
Maria Arnedo-Andrés and her crew have identified a single nucleotide polymorphism, or SNP, associated with pungency in chillies. 2 A snip is a single letter difference between the DNA of two different organisms. Sometimes a SNP makes a visible and important difference to the organism. The genetic difference that causes sickle cell anemia is one such SNP. More often, the SNP is just a marker. It is associated with some other difference, but does not actually cause it. Breeders like markers because they allow them to quickly see whether some desired gene has been inherited after a breeding experiment. If the marker is there, chances are the nearby gene is there too. There are gazillions of known SNPs out there, mapped to squillions of differences. But, until now, no SNP that could tell you whether a chilli pepper was hot.
There have been markers before, but they were either unreliable, failing to distinguish hot from sweet. Or they were physically a long way away from the actual genes for hotness, meaning that they were not very useful to breeders.
The researchers grew a wide range of peppers, different species and different varieties. Two people tasted five ripe fruits from each type of plant. If all five were not pungent, the plant was considered non-pungent. But if just one fruit (or more) tasted hot, the plant was considered pungent. Then comes the magic, actually detecting the sequence differences among the different samples.
They found one; in all pungent varieties, and only pungent varieties, there is a letter G at position 253 of an identifiable bit of DNA. In all non-pungent varieties, that space is taken by a T.
This result is just a beginning. Breeders will use the SNP to determine very early on, long before ripe fruits have been produced, whether those fruits will be hot or not. Researchers still don’t fully understand how plants make capsaicin. The SNP will help them home in on the genes responsible. And this blog will have taken the opportunity to use that nifty little icon up there on the right to indicate that we are serious and responsible members of the scientific blogosphere, dealing with peer-reviewed research in a serious and responsible manner.