Genetic Maize

As explained in the press release “Gene guards grain-producing grasses so people and animals can eat“, USDA  Agricultural Research Service (ARS) researchers at Purdue (pictured at left) have isolated the gene that confers fungus resistance to grasses. The gene produces an “enzyme that disarmed the fungus’ disease-causing toxin. The detoxification isolated the infection at the site where the fungus invaded.”
Previously known pathogen defense systems in plants depend on recognition of the pathogen, followed by localized cell death to isolate it, so this finding will lead to much research on how plants defend themselves. In my opinion, there is likely a whole family of toxin disarming enzymes. Once more genes are identified, it will be relatively easy to produce lines of important grasses (rice, maize, wheat, etc) that are resistant to many types of fungi. This can be done through either breeding or biotechnology – resulting in higher yields, reduction in human and animal sickness from fungal toxins, and reduction in fungicide use.
The abstract of “A guardian of grasses: Specific origin and conservation of a unique disease-resistance gene in the grass lineage” can be found at PubMed.

In Why your fertility cells must have ‘radio silence’, researchers from Canada and Japan explain their discovery: “a previously unknown mechanism which causes embryonic germ cells – which later develop into sperm or ova – to go through a period of ‘transcriptional silence,’ during which information from the cell’s DNA cannot be copied. Without this important phase, unique to cells of this type, an organism produces sterile offspring.”
A single protein called Transcription Elongation Factor B is produced by the Polar Granule Component gene. Female fruit flies lacking the pgc gene have sterile offspring. The researchers think the protein plays a major role in initiating the transcriptional silence. Conseidering that they found this to be true in both nematodes and fruit flies, it is reasonable to expect that it is true for other animals as well.
I could be misinterpreting this (I am not an animal biologist, after all), but this discovery could advance cloning. I don’t just mean the cloning of whole organisms like sheep and cows, but cloning of adult human cells into stem cell lines that can be used to cure all sorts of diseases. Successful natural embryos require some sort of ‘reprogramming’ of their parental DNA before they can start anew. We know something happens, but don’t yet know the details. The problems of cloning, including low rate of success and developmental abnormalities could be happening because the genomes weren’t properly reprogrammed. Is this ‘transcriptional silence’ part of the ‘reprogramming’ process? It’s certainly possible. I’m looking forward to research on what happens when they induce expression of the pgc gene in cloned cells, and what happens if they add P-TEFb. Will they be able to boost the success rate while reducing the number of deformed animals? I hope so. It would be really nice to have some good therapeutic cloning methods around by the time I start to need them.
The abstract of the Nature paper “Drosophila Pgc protein inhibits P-TEFb recruitment to chromatin in primordial germ cells” can be found on PubMed.

An effort to protect the world’s germplasm will culminate in the opening of the Svalbard Global Seed Vault on 26 February 2008, as reported by the BBC. This is a great idea, especially as habitat loss combines with climate change. We’re going to loose a lot of species and sub-species, which could leave the food supply vulnerable. Crop breeders use lines from many sources to put together the best varieties. Genetic engineers also need a source of diverse genes. Loosing too many wild and cultivated varieties of food crops could increase the chances of loosing a species to disease, climate change, etc. In other words, without a large enough gene pool, the species might not recover from a disaster.
I do want to point out again that the USDA has had a similar program for years. I actually worked for a branch of it in Maryland. The program is called the National Plant Germplasm System of the Agricultural Research Service (NPGS, ARS). As of 27 Jan 2008, the holdings include: 219 families, 2022 genera, 12486 species, and 484305 ascensions.
Just to give you an idea of the vast size of this program, NPGS has 25600 ascensions of maize from over 100 countries, 1852 ascensions of watermelon from over 70 countries, and 120 ascensions of pineapple from over 20 countries. Each ascension has the following data associated with it: “when the accession was received by the NPGS, the improvement status, reproductive uniformity, all names associated with the accession, intellectual property rights status, availability, general narrative, pedigree narrative, collection site description, source history including people responsible for acquiring, and any observation data.”
These people aren’t just collecting seeds. Seeds from many types of plants have declining germination rates over time, so to keep the lines alive, the seeds have to be planted and new seeds harvested every so often. Some plants, like many types of potatoes, don’t grow well from seed, so have to be grown from a tuber. Others have to be grown from cuttings. These “alternative reproduction methods” of plants make keeping them alive very complicated: the plants have to be re-cut and transferred to new containers every few months.
I’m keen to make this known because I feel that the plant side of the USDA gets ignored. When the USDA is mentioned, it’s usually in a negative light. I hope that people know that the meat side and the plant side of the USDA are entirely different entities.