Abscisic acid (ABA) regulates plant adaptive responses to various environmental stresses. Oxidative cleavage of cis-epoxycarotenoids catalyzed by 9-cis-epoxycarotenoid dioxygenase (NCED) is the main regulatory step in the biosynthesis of ABA in higher plants. Using RACE technology, a full-length cDNA-encoding
NCED gene was isolated and characterized from the leaves of
Caragana korshinskii (Peashrub). The 2442-bp full-length
CkNCED1 had a 1818-bp ORF, which encodes a peptide of 605 amino acids. The deduced amino acid sequence of CkNCED1 protein shared high identity with other NCEDs. Southern blot analysis revealed that the gene
CkNCED1 was a single copy in the genome of
C. korshinskii. When
C. korshinskii plants were exposed to a water deficit, ABA accumulation was followed by large increases in
CkNCED1 mRNA in leaves and stems, but only a moderate increase in the roots. Conversely, rehydration of stressed leaves caused a rapid decrease in
CkNCED1 mRNA and ABA levels. RT-PCR and Quantitative real-time PCR analysis showed that salt stress rapidly induced the strong expression of
CkNCED1 in leaves and roots of
C. korshinskii, as well as ABA accumulation. The expression of
CkNCED1 and ABA accumulation was also induced by cold stress and the application of exogenous ABA. Taken together, these results suggest that
CkNCED1 likely plays a primary role in the biosynthesis of ABA in
C. korshinskii.
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