The Role of ABA in the Interaction between Citrus Fruit and .

Abscisic acid (ABA) protects citrus fruit against infection. The global mechanisms involved in the role of ABA in the -citrus fruit interaction are unknown. Here, we determine the transcriptome differences between the Navelate ( (L.) Osbeck) orange and its ABA-deficient mutant Pinalate, which is less resistant to infection. Low ABA levels may affect both the constitutive mechanisms that protect citrus fruit against and early responses to infection. The repression of terpenoid, phenylpropanoid and glutation metabolism; of oxidation-reduction processes; and of processes related to the defense response to fungus and plant hormone signal transduction may be one part of the constitutive defense reduced in the mutant against . Our results also provide potential targets for developing -citrus fruit-resistant varieties. Of those up-regulated by ABA, a thaumatin protein and a bifunctional inhibitor/LTP, which are relevant in plant immunity, were particularly remarkable. It is also worth highlighting (), induced by infection in Pinalate, and the gene, which was down-regulated by ABA, because the absence of OXS3 activates ABA-responsive genes in plants.