Effects of the Tiller Inhibition (tin) Gene in Winter Wheat.

Wheat (Triticum aestivum L.) with the ‘Gigas' or ‘Big Ear' characteristics are easy to distinguish from other commercial wheat.  The main distinguishing characteristics for ‘Gigas' wheat include: uniculm plants, large number of spikelets per spike and thick stem.  The reduction in tillering is due to a single recessive gene, designated tin, for tiller inhibition. The tin gene located on wheat chromosome 1AS.  It has been reported that spring wheat lines containing the tin gene had a 90% reduction in tillering when planted during the spring and summer, but if planted during late fall/winter the effect was only 30-50% reduction in tillering. 

In order to investigate the effect of the tin gene in a winter wheat background two sets of crosses were made. The first being a three-way cross between a CIMMYT line containing the tin gene, a large spike adapted winter wheat line from Purdue, and a profuse-tillering line.  Our goal was to produce a population that exhibited a wide range of traits for tillering, spike size, stem diameter, etc. The second cross was between a landrace from Afghanistan that produces a large ear and another large spike adapted winter wheat line from Purdue. From this cross, our goal was to look at another source for the large spike characteristics to be used for breeding purposes.

Our preliminary observations indicate that in winter wheat genetic backgrounds the reduction in tillering effect of the tin gene is not as significant as in spring wheat; while the spike size, kernels/spikelet and stem diameter are increased, as seen in spring wheat.  Our hypothesis is that in winter wheat, we can achieve moderate increase in spike size, kernels/spike, kernel weight and stem diameter; with only a moderate reduction in tillering. Through plant breeding techniques, our goal is to combine these traits that provide underutilized variation with current high yielding components to improve yield potential.