Controlling self-pollination

Not a day passes, it seems, without news of yet another important gene being identified and mapped. Not long after geneticists uncovered the trigger for flowering, we now have news that researchers at Cornell are close to tracking down the genes that regulate a plant’s ability to self-pollinate. Good news for breeders everywhere.

Flowering trigger uncovered

Some clever genetic manipulation has led scientists to identify the chemical that allows daylength to trigger flowering in plants – all plants, it looks like. It is the protein produced by the gene called Flowering Locus T, or FT. This means that crop beeders will now have a better shot at developing varieties which will flower at different latitudes, useful as climate zones shift due to climate change.

Bee immunity

We’ve spent some time on the big bee die off (although not on the mobile phones) as have many other blogs and newspaper articles. In the US, the problem has reached epidemic proportions and has raised serious concerns about the future of several crops that depend to a large degree on bee pollination. Unfortunately recent evidence seems to suggest that the problem, which has been called Colony Collapse Disorder (CCD) has been spotted in Europe, as well. The cause or causes of CCD are unknown, but the list includes the usual suspects ranging from transgenic crops and pathogens to global warming and newly developed pesticides. Oh yes, and cell phones.

So the e-publication of a paper due to appear in the Journal of Heredity (behind a paywall) is timely. It describes the heritability and genetic variation of a gene called abaecin which is a key component of the immune system of bees.

Bees, like nearly all eukaryotes, have an innate immunity, but are generally thought to lack the additional adaptive immune response, which we and most other vertebrate species have. That is to say insects can’t get the ‘flu and respond by making specific antibodies to the virus (In fairness, the notion that insects do not have an adaptive immune system has been challenged recently by studies in Drosophila. )

To find out whether abacein expression differed between bee populations, scientists at the US Department of Agriculture crossed several unrelated males into a homogeneous maternal background and then challenged the offspring with Paenibacillus larvae. This is the bacterium that causes American foulbrood, a widespread larval disease of bees. Subsequent measurements in affected larvae showed that the level of abaecin was moderately heritable but highly variable, differing by as much as 10,000 times between different lines. Why this is variation exists at all is a matter of speculation, but it might be due to selective pressures: an arms race between hosts and different pathogen strains or species.

At any rate an understanding of the components of the immune response in bees at the molecular level and the realization that there appears to exist considerable genetic variation that could be exploited would seem to offer one of the more promising approaches to selection for pathogen resistance. Whether that will stop CCD is anyone’s guess.

Cereals databases

Before I disappear for a few days of immersion in the First International Breadfruit Symposium back in Fiji, let me point to two somewhat complementary online resources on cereals genetic resources that I have come across – no doubt Jeremy will say and about time too – in the past couple of days.

The FIGS database brings together passport and evaluation data on bread wheat landraces from a number of the major genebanks and “allows the user to efficiently interrogate the data associated with this collection and provides the capacity to identify custom subsets of accessions with single and multiple trait(s) that may be of importance to breeding programs.” FIGS stands for “Focused Identification of Germplasm Strategy,” and the focus is on identifying material with resistance to abiotic and biotic stresses.

The other database is that of Israel’s Institute of Cereal Crop Improvement, which includes information on accessions of wild cereal relatives collected over the past 30 years. Again, there’s a particular focus on data on disease resistance.