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Hereditary and non-hereditary factors affecting starch content in potato tubers
Malá, Lucie ; Sedláková, Vladimíra (advisor) ; Dvořák, Petr (referee)
This literature review relates to the starch which is presented in potato tubers, and hereditary and non-hereditary factors that influence content of the starch. At the beginning of the work, the attention is paid to the potatoes itself, especially their general characteristics. It should also mention the content of substances in tubers and their impact on human health. Further, the work is focused on the main thema, especialy starch present in potato tubers. Starch has considerable importance for the entire national economy, currently used not only in the starch industry, but it is more frequently used in other industries, for example paper or textile industry. Starch is composed from two important polysaccharides, amylose and amylopectin which are described in details. There are factors, that may influence starch content in potato tubers, like genetic and environmental factors. The simplest genetic factor that can influence the content of starch in potato tubers is crossing. The biosynthesis of starch is very important, which depends on several enzymes that initiate the metabolic pathway. It is pyrophosphorylase, starch synthase (SS), enzymes branched starch (SBEs) and enzymes unbranched starch (DBES). Starch synthase plays an important role here, in particular her isoform GBSS (granule bound starch synthase), which synthesizes amylose. Amylopectin is synthesized by a complex of enzymes SSI, SSII, SSIII, SSIV. The manipulation of single sugar genes metabolism can affect the formation and composition of starch in any variety of potatoes. This manipulation is called transgenesis and her goal is the creation of new potato genotypes. We can produce potato starch with high amylose by inhibiting enzymes SBE A and SBE B. A starch with a high amount of amylose is highy asked from the industry, because starch has unique functional properties. It should be mentioned DNA markers that has connection with the cultivation of potatoes and offers new opportunities for selecting potatoes genotypes. With DNA markers is linked MAS analysis and the associated method PCR polymerase chain reaction method. Another important method is QTL method. The environmental factors which influence the starch content of potatoes, which are mentioned in this work, are drought, light, cold. It should also be noted that even postharvest stress has a negative effect on starch content in potato tubers. Environmental stress affects and changes the yield of the starch.
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