Zinc finger protein ZFP36 and pyruvate dehydrogenase kinase PDK1 are key
elements in the ABA-mediated aluminum tolerance in rice
Abstract
Aluminum (Al) toxicity is the major limiting factor for plant production
and crop yield on acid soils. Previous works revealed that ZFP36 played
a key role in plant adaptation to water stress and rice blast. Here, we
report another function of ZFP36, which is associated with
detoxification of Al toxicity through abscisic acid (ABA)- dependent
mechanism, in rice. Al exposure significantly increased ZFP36 expression
level in an ABA-dependent manner. Knocking down ZFP36 triggered Al
sensitivity, while overexpressing ZFP36 resulted in an increased Al
tolerance. Chromatin immunoprecipitation-sequencing (ChIP-seq), yeast
one-hybrid assay, and dual luciferase test revealed that a
tonoplast-localized Al transporter, OsALS1, and antioxidant defense
enzymes were targeted by ZFP36. Moreover, by combining yeast two-hybrid
assay, bimolecular fluorescence complement (BiFC), GST pull-down and in
vitro phosphorylation assay, we showed that ZFP36 could interact with
and be phosphorylated by the pyruvate dehydrogenase kinase OsPDK1. A
strong association was found between the expression, protein content and
kinase activity of OsPDK1 with the responses to ABA and Al. Using
transgenic plants, we have showed that OsPDK1 could inhibit OsALS1
expression via regulating ZFP36. Overall, our data demonstrates a new
ZFP36-controlled mechanism of Al defense in rice plants, which is
mediated by OsPDK1.