Connections between sphingosine kinase and phospholipase D in the abscisic acid signaling pathway in Arabidopsis.

ABSTRACT: Phosphatidic acid (PA) and phytosphingosine 1-phosphate (phyto-S1P) both are lipid messengers involved in plant response to abscisic acid (ABA). Our previous data indicate that PA binds to sphingosine kinase (SPHK) and increases its phyto-S1P-producing activity. To understand the cellular and physiological functions of the PA-SPHK interaction, we isolated Arabidopsis thaliana SPHK mutants sphk1-1 and sphk2-1 and characterized them, together with phospholipase D?1 knock-out, pld?1, in plant response to ABA. Compared with wild-type (WT) plants, the SPHK mutants and pld?1 all displayed decreased sensitivity to ABA-promoted stomatal closure. Phyto-S1P promoted stomatal closure in sphk1-1 and sphk2-1, but not in pld?1, whereas PA promoted stomatal closure in sphk1-1, sphk2-1, and pld?1. The ABA activation of PLD?1 in leaves and protoplasts was attenuated in the SPHK mutants, and the ABA activation of SPHK was reduced in pld?1. In response to ABA, the accumulation of long-chain base phosphates was decreased in pld?1, whereas PA production was decreased in SPHK mutants, compared with WT. Collectively, these results indicate that SPHK and PLD?1 act together in ABA response and that SPHK and phyto-S1P act upstream of PLD?1 and PA in mediating the ABA response. PA is involved in the activation of SPHK, and activation of PLD?1 requires SPHK activity. The data suggest that SPHK/phyto-S1P and PLD?1A are co-dependent in amplification of response to ABA, mediating stomatal closure in Arabidopsis.

SUBMITTER: Guo L 

PROVIDER: S-EPMC3318714 | biostudies-literature | 2012 Mar

REPOSITORIES: biostudies-literature