The wheat (T. aestivum) sucrose synthase 2 gene (TaSus2) active in endosperm development is associated with yield traits

Abstract

Sucrose synthase catalyzes the reaction sucrose + UDP → UDP-glucose + fructose, the first step in the conversion of sucrose to starch in endosperm. Previous studies identified two tissue-specific, yet functionally redundant, sucrose synthase (SUS) genes, Sus1 and Sus2. In the present study, the wheat Sus2 orthologous gene (TaSus2) series was isolated and mapped on chromosomes 2A, 2B, and 2D. Based on sequencing in 61 wheat accessions, three single-nucleotide polymorphisms (SNPs) were detected in TaSus2-2B. These formed two haplotypes (Hap-H and Hap-L), but no diversity was found in either TaSus2-2A or TaSus2-2D. Based on the sequences of the two haplotypes, we developed a co-dominant marker, TaSus2-2B ( tgw ), which amplified 423 or 381-bp fragments in different wheat accessions. TaSus2-2B ( tgw ) was located between markers Xbarc102.2 and Xbarc91 on chromosome 2BS in a RIL population from Xiaoyan 54 × Jing 411. Association analysis suggested that the two haplotypes were significantly associated with 1,000 grain weight (TGW) in 89 modern wheat varieties in the Chinese mini-core collection. Mean TGW difference between the two haplotypes over three cropping seasons was 4.26 g (varying from 3.71 to 4.94 g). Comparative genomics analysis detected major kernel weight QTLs not only in the chromosome region containing TaSus2-2B (tgw), but also in the collinear regions of TaSus2 on rice chromosome 7 and maize chromosome 9. The preferred Hap-H haplotype for high TGW underwent very strong positive selection in Chinese wheat breeding, but not in Europe. The geographic distribution of Hap-H was perhaps determined by both latitude and the intensity of selection in wheat breeding.

QTL detection for wheat kernel size and quality and the responses of these traits to low nitrogen stress

“…In this study, QTL mapping analysis showed that the TaCwi-A1a allele may be associated with not only an increased kernel size but also improved kernel milling and baking quality and that it could enhance the tolerance of both quality and yield to N stress. The sucrose synthase 2 (Sus2) gene is associated with wheat yield (Jiang et al 2011;Liu et al 2012;Rasheed et al 2014). In this study, QTL mapping analysis showed that TaSus2 had opposite effects on the yield and quality traits.…”

“…In most cases, a functional marker of a gene co-localizes with the QTL peak position for the same trait (Sourdille et al 2003). To date, numerous functional markers have been discovered that facilitate analyses of the co-localization of identified QTLs with known genes (Giroux and Morris 1997;Lei et al 2006;He et al 2009;Wang et al 2010;Jiang et al 2011;Ma et al 2012). Moreover, QTL analysis based on genetic mapping, including analysis of functional markers, can reveal novel functions of important genes that are indirectly correlated with yield and quality traits.…”

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

“…Similar genes are present in barley (Hordeum vulgare) and wheat. In wheat, TaSus2 is located on homeologous group 2 chromosomes (Jiang et al, 2011). Three single nucleotide polymorphisms (SNPs) in TaSus2-2B form two haplotypes, Hap-H and Hap-L. Hap-H, the favored haplotype associated with higher TKW, underwent strong positive selection in Chinese wheat breeding as a consequence of selection for higher grain yield (Jiang et al, 2011).…”

“…Starch is located in the cytosol (Kleczkowski et al, 2010). SUS also plays key roles in fruit and seed maturation (Coleman et al, 2010;Jiang et al, 2011) and abiotic stress tolerance (Bologa et al, 2003;Yang et al, 2004;Bieniawska et al, 2007).…”

The Structure of Sucrose Synthase-1 from Arabidopsis thaliana and Its Functional Implications

“…The SUS reaction therefore provides a direct and reversible link in sucrose metabolism between respiration, carbohydrate biosynthesis, and carbohydrate utilization (1), as well as allowing the rapid conversion of a sucrose sink into a sucrose source without the synthesis or degradation of enzymes (2,4). Although invertases have a critical role in normal plant growth (5,6), SUS is clearly involved in pollen tube growth (7,8), the establishment of nitrogen fixation (9 -12), biomass production (13,14), and fruit and seed maturation (13,15,16), particularly during periods of abiotic stress (6,(17)(18)(19). SUS participates in the regulation of sucrose flux by rapidly altering its cellular location from the cytosol to sites of cellulose, callose, and starch biosynthesis (7, 20 -22), and through its interaction with various organelle membranes (4,23,24) and cytoskeletal actin (25,26).…”