Effect of temperature on expression of genes encoding enzymes for starch biosynthesis in developing wheat endosperm

Physicochemical characterization of starch from hexaploid triticale (X TriticosecaleWittmack) genotypes

“…The low starch accumulation in substituted triticales suggested that high growing temperatures might have caused an earlier cessation of starch synthesis such as that reported for wheat (Hurkman et al, 2003;Liu et al, 2011). Low starch contents, such as those observed in substituted triticales although with similar amylose contents to the complete triticales, open the possibility that the bread wheat SBEIIb genes might have been silenced with no effect on amylose synthesis as has been observed in wheat (Regina et al, 2005).…”

“…High growing temperatures adversely affect starch accumulation in barley (MacLeod & Duffus, 1988), corn (Jones, Roessler, & Ouattar, 1985;Tester, South, Morrison & Ellis, 1991) and wheat (Chowdhury & Wardlaw, 1978;Liu et al, 2011;Tester et al, 1995), leading to reduction in starch accumulation and grain size. Hurkman et al (2003) observed that high temperatures during grain filling of wheat caused a decrease in starch content primarily due to the reduction in the duration of starch accumulation. Temperatures higher than 25°C adversely affect the activity of soluble starch synthase in the wheat endosperm, reducing the Mean values of amylose content in A-type and B-type starch granules are expressed in percentage ± standard deviation.…”

“…duration of starch accumulation (Hawker & Jenner, 1993;Keeling et al, 1993) as well as the expression of gene encoding enzymes for starch biosynthesis (Hurkman et al, 2003). Differences in starch content between the triticale genotypes might also be due to the existence of null alleles on the short arms of chromosomes 7A (Wx-A1) and 7D (Wx-D1) and the long arm of chromosome 4A (Wx-B1), all derived from wheat, which code for the synthesis and expression of starch synthase (Fujita et al, 1996;Yamamori, Nakamura, Endo, & Nagamine, 1994).…”

“…Zhang et al (2010) observed that GBSS I was expressed during the mid to late filling stage of wheat grains under development. However, at that stage of kernel maturation the environmental temperatures start to increase, affecting the enzyme activity as well as gene expression (Hurkman et al, 2003). Therefore, it is supposed that GBSS I might have been less active or in lower amounts possibly due to the sensitivity of substituted triticales to high temperatures at which they were grown (Liu et al, 2011;Zhao, Dai, Jiang, & Cao, 2008) in comparison to complete triticales.…”

“…Starch is by far the most abundant component of cereal grains, and its synthesis and composition are influenced by the genotype and environment (Hurkman et al, 2003;Liu et al, 2011). In general, triticales contain around 62.4-70.9% of starch with approximately 20.8-26.4% of amylose content (Burešová, Sedláčková, Faměra, & Lipavský, 2010).…”