The Localization Study Of Flavin-monooxygenases FMO_GS-OX4,6,7 Involved In Aliphatic Glucosinolate Side-chain Modification

Glucosinolates (GSLs) are nitrogen-and sulfur-containing natural plant secondary metabolites which derived from amino acid, widely exist in Cruciferae plants include model organism Arabidopsis and a large number of vegetable crops with economic value. The predominant biological activities of glucosinolates are associated with their breakdown products by the action of the myrosinases and these hydrolysis products have important biological activities in resistance to insects and pathogens. For humans, some certain glucosinolates hydrolysis products have cancer-preventing activity. The bioactivity of GSLs is closely related with its chain structure and length. There are5FMO (Flavin-containing Monooxygenase) enzyme genes FMOGS-OX1, FMO GS-OX2, FMO GS-OX3, FMO GS-OX4and FMO GS-OX5involved in GSLs transformation of the S-oxygenation from Methylthioalkyl GSLs to Methylsulfinylalkyl GSLs. Our previous work showed that except fmogs-ox4the four other FMO Gs-OX loss of function mutants all present altered GSLs phenotypes. In order to reveal the FMO GS-OX4expression characteristic and its function in GSLs chain structure modification we analyzed FMOGS-ox4expression pattern in different tissues using GFP and GUS as reporter genes. Gene ATIg12130and ATlg12160have a very closely genetic relationship with the five FMOGs-ox, overexpression ATlg12130and ATlg12160plants also appeared the unnormal proportional between Methylthioalkyl GSLs and Methylsulfinylalkyl GSLs demonstrated that these two genes are also involved in GSLs transformation of the S-oxygenation from Methylthioalkyl GSLs to Methylsulfinylalkyl GSLs,named FMOGs-ox6and FMOGs-oX7. So we analyzed the FMOGs-ox4expression pattern in different tissues using GUSas reporter genes to reveal the expression characteristic of FMOGs-ox6and FMOGs-ox7. FMOGs-ox4expression pattern shows that FMOGs-ox4express mainly in the vascular tissue of leaf, stem and silique. Under normal conditions, spacial distribution of FMOGs-ox4was not overlapped with the distribution of its substrates, which was considered as the reason for the lacking altered glucosinolates phenotype in fmogs-ox4. Expression pattern of FMOGs-ox6and FMOGs-ox7are similar to the five well-known FMOGs-OX, express mainly in the vascular tissue of leaf, silique and flower and similar to the other GSLs biosynthetic genes expression characteristic. Therefore, combined identification of chemical phenotypes of FMOGs-ox6and FMOGs-ox; overexpression plants we initially identified FMOGS-OX6and FMOGS-ox7are aliphatic glucosinolate side chain modifying enzyme genes.