fa and fas - (Fasciata)

The dictionary defines 'fasciation' botanically as a common malformation in plant stems resulting in enlargement and flattening, as if several stems were fused. That describes well the expression of the fa and fas mutations in pea. If you click on the image above, and look at the upper portion of this stem, you'll see that the stem is far wider than that found on a regular stem, and is ridged. What you can't see in this photo is that the stem low to the ground appears to look pretty normal. As you follow the stem up the plant, you notice that there is little or no branching off of the main stem. Instead it just gets wider and wider, and shows more of the ridges you see in the above photo. You also note that there are few or no flowers lower on the plant. Nearly all of the flowers appear in a cluster right at the top of the plant. This feature is what Gregor Mendel referred to as axial or terminal flowering, when he used this mutation in his first genetic studies.

These genes were reported by Lamprecht to be polymeric and duplicate. These genes are recessively inherited, and are mapped to linkage groups III for fas, and IVA for fa. We only have the allele fa documented in this collection, and it occurs in 22 accessions. We also have 14 accessions in the PI collection that express this trait. If you would like to query on this trait in the genstocks collection, click here .