Impact of gene expression of chosen genes involved in the biosynthetic pathway of vitamin E on the total vitamin E content and composition in grain of spring barley

摘要

Vitamin E has a very important role in human nutrition. Sources of vitamin E are i.e. oils, nuts and also cereals. The highest vitamin E content among cereals was detected in barley. There are two enzymes localized in the strategic location of biosynthetic pathway of vitamin E : 4-hydroxyphenylpyruvate dioxygenase enzyme (HPPD) and homogentisategeranylgeranyl transferase (HGGT). HPPD could be considered as one of the essential factors which could control activity of the whole biosynthetic pathway due to its localization in the beginning of biosynthetic pathway. HGGT is the only enzyme which differs in the biosynthetic pathway of tocopherols and tocotreinols and that is why it could cause changes in the composition of vitamin E. Seven barley cultivars with different vitamin E level were grown under controlled conditions and activity of HPPD and HGGT in ears was measured four, eight and twelve days after pollination. It was found that activity of HPPD gene corresponded with the final vitamin E content detected in grains (r = 0,75~*). Relationship was found between gene activity of HPPD eight and twelve days after pollination and vitamin E content which was typical for these cultivars in the field conditions (r = 0,85~*). Gene for HGGT had smaller correlation to tocotrienol content.%Vitamín E plní velmi d?le?itou úlohu v lidské vy?ivě. Mezi vyznamné zdroje vitamínu E se ?adí nap?íklad oleje; o?echy a také obiloviny. Nejvy??í obsah vitamínu E mezi obilovinami byl detekován v je?meni. V biosyntetické dráze vitamínu E se na klí?ovych místech nacházejí tyto enzymy - 4-hydroxyphenylpyruvát dioxygenasa (HPPD) a homogentisátgeranylgeranyl transferasa (HGGT). HPPD m??e byt pova?ována za enzym; ktery by mohl; vzhledem ke své pozici v biosyntetické dráze; ovlivňovat aktivitu celé biosyntetické dráhy. HGGT je jedinym enzymem; kterym se li?í biosyntetická dráha tokoferol? a tokotrienol?; a mohl by proto mít vliv na zastoupení jednotlivych izomer? vitamínu E. Sedm odr?d je?mene jarního bylo pěstováno za kontrolovanych podmínek a byla mě?ena aktivita gen? pro HPPD a HGGT v klasech odebranych ?ty?i; osm a dvanáct dní po opylení. Bylo zji?těno; ?e aktivita genu pro HPPD koresponduje s vyslednym obsahem vitamínu E v zrnu (r = 0;75~*). Byl zji?těn vztah mezi aktivitou genu pro HPPD osm a dvanáct dní po opylení a obsahem vitamínu E; ktery je pro pěstované odr?dy typicky v polních podmínkách (r = 0;85~*). Byla zji?těna pouze malá závislost mezi aktivitou genu pro HGGT a vyslednym obsahem tokotrienol? v zrnu.