Translocation and accumulation of dry matter in winter wheat genotypes

In the years 2003 and 2004, diametrically different in temperature, in total amount of precipitation and in its distribution during vegetation, winter wheat lines in generations F 4 and F 5 . originated from seven crossings, and with three local adapted varieties, were examined in field experiments. This study was conducted to assess effects of year and genotype on the rate of biomass produced till anthesis from total one at maturity and the rate of photosynthate produced before anthesis in grain. In hot and dry conditions of the year 2003, in comparison to 2004 (higher precipitation, lower temperature), lower total biomass was produced (1258 g.m −2 to 1859 g.m −2 ), higher rate of accumulated biomass till anthesis (60 % to 52 %) and higher portion of translocated biomass in grain (15 % to −13.6 %), and lower grain yield (591 g.m −2 to 782 g.m −2 ) were observed. Differences occurred among crossings and lines within crossing in ratio of photosynthate produced till anthesis in grain. The ratio of translocated photosynthate in grain on one side and grain yield and total produced biomass on the other side, were negative correlated. Genotypes with high proportion of translocated dry matter in grain are recommended for marginal growing areas. For intensive growing areas, genotypes with high biomass production and with higher biomass portion from anthesis to maturity are required. Rate of translocated biomass in grain depends on the harvest index, and on the portion of biomass produced till anthesis from the total one

Phenolic Compounds in Wheat Kernels: Genetic and Genomic Studies of Biosynthesis and Regulations

Whole wheat grains are an important source of bioactive components, particularly of phenolic acids and flavonoids. Due to the health-promoting effects of these phenolics, nowadays, the increase of their content in mature kernels is of great interest and a potential target for wheat breeding programs. The biogenesis of phenolics occurs through the general phenylpropanoid pathway, which is ubiquitous in plant cell walls and leads to the synthesis of secondary metabolites that are involved in plant defence and structural support. This chapter reviews the current knowledge in phenylpropanoid chemistry, and the genetic and molecular basis for the biosynthesis of phenolic acids and anthocyanins in wheat grains. Also, advances in assessing genetic variation in the content and composition of these components in wheat germplasm are reviewed, including the effects of different environmental conditions on their accumulation in mature kernels. The recent, ongoing genomic studies are reviewed providing updates on quantitative trait loci and genes involved in the synthesis and accumulation of phenolics in wheat kernels. Finally, the promise and limitations of breeding programs to potentially develop wheat cultivars rich in phenolic components are discussed