A putative pyruvate transporter TaBASS2 positively regulates salinity tolerance in wheat via modulation of ABI4 expression

Abstract

Background: High salinity adversely affects crop production. Pyruvic acid is the precursor of abscisic acid (ABA) and other chemicals that are synthesized in chloroplast, some of which are involved in the response to salt. The transportation of pyruvic acid into chloroplast is mediated by pyruvate transporters. However, whether pyruvate transporters are involved in salt response has not been studied so far. Here, we answered this issue by assessing the function of a wheat pyruvate transporter in salt response. Results: A pyruvate transporter TaBASS2 was isolated from salt-tolerant wheat cultivar Shanrong 3. The expression of TaBASS2 was induced by NaCl stress as well as H2O2 and ABA treatments. Constitutive expression of TaBASS2 in Arabidopsis bass2-1 mutant complemented the mevastatin-sensitive phenotype that reflects the deficiency of transporting pyruvic acid into chloroplast. Overexpression of TaBASS2 enhanced salinity tolerance and reactive oxygen species scavenging in wheat. Arabidopsis constitutively expressing TaBASS2 also exhibited enhanced tolerance to salinity and oxidative stress. In Arabidopsis, TaBASS2 repressed the expression of ABA INSENSITIVE 4 (ABI4), a node linking ABA signaling and plastid retrograde signaling pathways. However, the enhanced salinity tolerance of TaBASS2 overexpression Arabidopsis was abolished when ABI4 expression was restored to the level of wild-type through overexpressing ABI4. Conclusions: Our work demonstrates that TaBASS2 enhances salinity tolerance of plants via modulating ABI4 expression. This indicates that pyruvate transporters indeed participate in the interaction of plants with environmental stimuli.