Global Selection on Sucrose Synthase Haplotypes during a Century of Wheat Breeding

Abstract

Spike number per unit area, number of grains per spike, and thousand kernel weight (TKW) are important yield components. In China, increases in wheat (Triticum aestivum) yields are mainly due to increases in grain number per spike and TKW. TKW mainly depends on starch content, as starch accounts for about 70% of the grain endosperm. Sucrose synthase catalysis is the first step in the conversion of sucrose to starch, that is, the conversion of sucrose to fructose and UDP-glucose by the wheat sucrose synthase genes (TaSus1 and TaSus2) that are located on chromosomes 7A/7B/7D and 2A/2B/2D, respectively. A total of 1,520 wheat accessions were genotyped at the six loci. Two, two, five, and two haplotypes were identified at the TaSus2-2A, TaSus2-2B, TaSus1-7A, and TaSus1-7B loci, respectively. Their main variations were detected within the introns. Significant differences between the haplotypes correlated with TKW differences among 348 modern Chinese cultivars from the core collection. Frequency changes for favored haplotypes showed gradual increases in cultivars released since beginning of the last century in China, Europe, and North America. Geographic distributions and time changes of favored haplotypes were characterized in six major wheat production regions worldwide. Strong selection bottlenecks to haplotype variations occurred at polyploidization and domestication and during breeding of wheat. Genetic-effect differences between haplotypes at the same locus influence the selection time and intensity. This work shows that the endosperm starch synthesis pathway is a major target of indirect selection in global wheat breeding for higher yield.

Genome‐wide association analyses of 54 traits identified multiple loci for the determination of floret fertility in wheat

“…We assessed the haplotype information for the candidate gene‐ TaSus1‐7A in the 210 wheat genotypes. The two favorable haplotypes of TaSus1‐7A_Hap‐1 and TaSus1‐7A_Hap‐2 were detected with frequencies of 18% and 68%, respectively (Table S7) (Hou et al ., ). This implies that sucrose metabolism is associated with the determination of floret fertility (Figs.…”

A yield-associated gene TaCWI, in wheat: its function, selection and evolution in global breeding revealed by haplotype analysis

“…Hou et al (2014) showed that genetic differences influenced haplotype selection and intensity in cultivar populations. There was no significant difference between the two haplotypes in 348 modern cultivars.…”

“…In landraces the frequency of Hap-5D-C was 66.5 %, but in modern cultivars released after the 1950s it was 91.3 % (Fig. In irrigated areas, there is positive selection for large spikes with high TKW and GN (Zhou et al 2007;Hou et al 2014). Hap-5D-C is associated with superior (Table 7).…”

In vitro allelopathic effect of aqueous extracts of sugarcane on germination parameters of wheat

“…After maize and rice, wheat is ranked the third most widely produced grain crops in the world which has significant impact on meeting global food demands and dietary needs (Hou et al, 2014). The crop in Pakistan is generally cultivated in rotation with several other crops such as maize, rice, tobacco and sugarcane.…”