Effect of the tiller inhibition (tin) gene in winter wheat
Wheat (Triticum aestivum L.) with the ‘Gigas’ or ‘Big Ear’ characteristics is easy to distinguish from other commercial wheat. The main distinguishing characteristics for ‘Gigas’ wheat include: uniculm plants, large number of spikelets per spike and a thick stem. The reduction in tillering is due to a single recessive gene, designated tin, for tiller inhibition. The tin gene is 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. One of the objectives of this study was to determine the effect of the tin gene in a winter wheat background on agronomic performance. A second objective of this study was to identify QTL for traits that are associated with the tin gene, which include spike length, number of spikelets per spike, seeds per spikelet, grams of seed per spike, plant height, and stem diameter. In the first experiment to investigate the effect of the tin gene on the agronomic performance of winter wheat, two doubled haploid (DH) populations were produced. The DH lines were selected for being either free tillering or tin. The first experiment evaluated the agronomic performance at two locations during the 2013/2014 season. The tin lines produced significantly fewer spikes per m2 but significantly more spikelets per spike, seeds per spikelet, grams of seed per spikelet, and had wider stems. Even though there was a significant reduction in the yield (measured as number of seeds per m2) of tin lines, high-yielding lines containing the tin gene were still identified. In the second experiment to identify QTL controlling traits that are associated with the tin gene, an F2 mapping population was used. The plants were grown in the greenhouse during the spring of 2013. A single QTL was identified for three of the eight traits studied. QTL were identified for the number of spikes per plant on 1A, number of seeds per spikelet also on 1A, and grams of seed per spike on 6B. The results of these studies provide potential genetic sources which could be utilized by breeders. Combining this underutilized variation with current high-yielding components could be useful to improve yield potential in wheat.
Scofield, Purdue University.
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