Induction of a Citrus gene highly homologous to plant and yeast thi genes involved in thiamine biosynthesis during natural and ethylene-induced fruit maturation

Maturing citrus fruit undergo pigment changes which can be enhanced by exogenous ethylene. In order to identify genes induced by ethylene in citrus fruit peel, we cloned the gene c-thil. mRNA corresponding to c-thil increased gradually in the peel during natural fruit maturation and in response to ethylene. GA(3) pretreatment reduced the inductive effect of ethylene. Levels of c-thil increased also in juice sacs but the effect of ethylene was much less prominent. c-thil is homologous to yeast and plant genes encoding for an enzyme belonging to the pathway of thiamine biosynthesis, The data suggest that thiamine is involved in citrus fruit maturation.