Geographic distribution of TaSSIV-A and TaSSIV-B Haplotypes in China. (a,c) Landraces, (b,d) modern cultivars. I, Northern winter wheat region; II, Yellow and Huai River valleys winter wheat region; III, Middle and low Yangtze valleys winter wheat region; IV, Southwestern winter wheat region; V, Southern winter wheat region; VI, Northeastern spring wheat region; VII, Northern spring wheat region; VIII, Northwestern spring wheat region; IX, Qinghai-Tibetan spring-winter wheat region; X, Xinjiang winter-spring wheat region. Pie chart size is directly proportional to number of genotypes.