Effects Of Cutin Related Genes On CK Signal And Light Signal Pathway

The plant hormones referred to as cytokinins(CKs)are chemical signals that control numerous developmental processes throughout the plant life cycle.Through the study of Arabidopsis thaliana,CK biosynthesis,metabolism and signaling pathway are gradually known to the researchers.However,there are few studies on the molecular mechanism of the interaction between CK signaling pathway and fatty acid metabolism.By way of genetic screen,we isolated an Arabidopsis mutant named grow fast on cytokinins(gfc1),whose seedlings grew larger after CK treatment.gfc1 is allelic to a previously reported cutin mutant dcr(defective in cuticular ridges),and GFC1/DCR encodes a soluble BAHD acyltransferase(a name based on the first four enzymes characterized in this family:Benzylalcohol O-acetyltransferase,Anthocyanin O-hydroxycinnamoyltransferase,anthranilate N-hydroxycinnamoyl/benzoyltransferase and Deacetylvindoline 4-O-acetyltransferase)with diacylglycerol acyltransferase(DGAT)activity and is necessary for normal cuticle formation on epidermis.Here we observed that,when gfc1-1 was induced by CK,it showed large cotyledon in long day and typical de-etiolation phenotype in darkness.In addition,the background expression levels of most type-A arabidopsis response regulator(ARR)genes were higher in the gfc1 mutant,and the expression of AHKs(arabidopsis histidine kinases)and AHPs(arabidopsis histidine-containing phosphotransfer proteins)was similar to that of wild type.The expression of HY5(elongaed hypocotyl5)was higher in gfc1,which is required for positive regulation of photomorphogenesis.While,the expression of PIFs(phytochrome interacting factor)were lower,which is required for positive regulation of skotomorphogenesis.The gfc1-associated phenotypes were also observed in the cutin-deficient double mutant gpat4/8(glycerol-3-phosphate acyltransferase 4/8)and alpha beta hydrolase mutant bdg1(bodyguard1),but not in the cutin-deficient mutant cyp86A2/cyp86A8(cytochrome p450 family 86 subfamily A polypeptide 2/8),abcg11(ATP binding cassette transporters g11),pec1(permeable cuticle1)and lacs1(long-chain acyl-coa synthase1).Our results indicate that some acyltransferases associated with cutin formation are involved in CK responses and skotomorphogenesis in Arabidopsis.