Identification of Quantitative Trait loci and Environmental Interactions for Accumulation and Remobilization of Water-Soluble Carbohydrates in Wheat (Triticum aestivum L.) Stems

Abstract

Genetic analyses of nine traits associated with stem water-soluble carbohydrate (SWSC) accumulation and remobilization at grain-filling period under drought stress (DS) and well-watered (WW) conditions were undertaken using doubled haploid lines (DHLs) derived from two Chinese common wheat cultivars. Some significantly and very significantly positive correlation was observed among nine traits associated with SWSC. Higher phenotypic values for most traits were detected under DS. Broad sense heritabilities (h 2 B ) of the traits showed wide fluctuations between two water treatments. A total of 48 additive and 62 pairs of epistatic QTL for nine traits were identified as distributing on all 21 chromosomes. A majority of QTL involved significant additive and epistatic effects with interactions of QTL and environments (QEIs). Two additive and two pairs of epistatic loci involved only QEIs without corresponding significant additive or epistatic effects. The contributions of the additive QEIs were two-to fourfolds higher than those of their corresponding additive QTL. Most of the additive QEIs for traits associated with SWSC interacted with DS. In addition, some QTL for the grain-filling efficiencies and thousand-grain weight were colocated in the same or adjacent chromosome intervals with QTL for accumulation and remobilization efficiency of SWSC before 14 days after flowering.

Genetic Dissection of Stem Water-Soluble Carbohydrates and Agronomic Traits in Wheat under Different Water Regimes

“…According to Rebetzke et al (2007), the QTL on chromosome 2D was also mapped for WSC. It was also supported by Yang et al (2007), but they reported QTL for WSC away from those markers that we found, and also it was reported at flowering stage. Dodig et al (2012) identified SSR marker Xgwm484 (41 cM) for chlorophyll content at grain filling but far distance from that marker we reported.…”

“…The distance among these markers were less than 10 cM. Yang et al (2007) detected QTL with flanking marker of Xwmc524~Xgwm595 for TGWG, it was on the same chromosome as our studies but with different position and also was associated with same trait as in this study. Furthermore, (Maccaferri et al, 2011) found Xbarc197 located on chromosome 5A (53 cM) adjacent with Xgwm293 (52 cM) and also nearby Xgwm415 and Xgwm304 (56 and 61 cM apart), was associated with grain yield using association analysis.…”

“…It is suggested that SWSCG could play a key function in the subsequent release of carbohydrates from stem to grain. Current results are in conformity by Yang et al (2007). WSC are recognized as an important source of grain dry matter for grain filling, especially when current photosynthesis is inhibited by drought stress.…”

“…In term, high water-soluble carbohydrate content in the stem has been suggested as a selection criterion for use inbreeding. WSC QTL have been reported in rice (Nagata et al, 2002;Takai et al, 2005), wheat (Rebetzke et al, 2008;Yang et al, 2007), maize (Thévenot et al, 2005), barley (Teulat et al, 2001) and perennial rye grass (Turner et al, 2006). With the rapid increases in number of molecular markers, association analysis has become an important tool for dissection of complex traits (Bradbury et al, 2007).…”

Yield stability for cereals in a changing climate

“…Water-soluble carbohydrates are important for maintaining grain size, particularly under drought conditions when photosynthesis is arrested (Gebbing et al 1999;Yang et al 2001;Ruuska et al 2006Ruuska et al , 2008. Genetic variation in the ability to mobilise stem reserves to the developing grain has been identified and used for biochemical characterisation and QTL mapping (Yang et al 2007;Ehdaie et al 2008;Xue et al 2008). The staygreen trait, which is characterised by delayed leaf senescence, is generally considered to improve tolerance at the vegetative stage to mid-season droughts (Thomas and Howarth 2000), but the trait may also interfere with carbohydrate mobilisation to the reproductive structures and affect grain-filling (Blum 1998; Sanchez et al 2002;Collins et al 2008;Blum 2011).…”