%0 Journal Article 
%A Izquierdo-Bueno Reina, Inmaculada Concepción
%A González Rodríguez, Victoria Eugenia
%A Simon, Adeline
%A Dalmais, Bérengère
%A Pradier, Jean-Marc
%A Le Pêcheur, Pascal
%A Mercierz, Alex
%A Walker, Anne-Sophie
%A Garrido Crespo, Carlos
%A González Collado, Isidro
%A Viaud, Muriel
%T Biosynthesis of abscisic acid in fungi: identification of a sesquiterpene cyclase as the key enzyme in Botrytis cinerea
%D 2018
%U http://hdl.handle.net/10498/33284
%X While abscisic acid (ABA) is known as a hormone
produced by plants through the carotenoid pathway,
 a small number of phytopathogenic fungi are also
 able to produce this sesquiterpene but they use a dis-
 tinct pathway that starts with the cyclization of
 farnesyl diphosphate (FPP) into 2Z,4E-a-ionylidene-
 ethane which is then subjected to several oxidation
 steps. To identify the sesquiterpene cyclase (STC)
 responsible for the biosynthesis of ABA in fungi, we
 conducted a genomic approach in Botrytis cinerea.
 The genome of the ABA-overproducing strain
 ATCC58025 was fully sequenced and five STC-coding
 genes were identified. Among them, Bcstc5 exhibits
 an expression profile concomitant with ABA produc-
 tion. Gene inactivation, complementation and
 chemical analysis demonstrated that BcStc5/BcAba5
 is the key enzyme responsible for the key step of
 ABA biosynthesis in fungi. Unlike what is observed
 for most of the fungal secondary metabolism genes
the key enzyme-coding gene Bcstc5/Bcaba5 is not 
clustered with the other biosynthetic genes, i.e.
Bcaba1 to Bcaba4 that are responsible for the oxida- 
tive transformation of 2Z,4E-a-ionylideneethane. 
Finally, our study revealed that the presence of the 
Bcaba genes among Botrytis species is rare and that 
the majority of them do not possess the ability to pro- 
duce ABA.
%~ Universidad de Cádiz