Sethoxydim treatment inhibits lipid metabolism and enhances the accumulation of anthocyanins in rape (Brassica napus L.) leaves.

Cyclohexanediones (e.g., sethoxydim) are known to be inhibitors of plastid acetyl-CoA carboxylase (ACCase) of monocotyledonous plants and provoke plant death.

Phytosphingosine-phosphate is a signal for AtMPK6 activation and Arabidopsis response to chilling.

• Long-chain bases (LCBs) are pleiotropic sphingolipidic signals in eukaryotes. We investigated the source and function of phytosphingosine-1-phosphate (PHS-P), a phospho-LCB rapidly and transiently formed in Arabidopsis thaliana on chilling. • PHS-P was analysed by thin-layer chromatography following in vivo metabolic radiolabelling.

Respiratory complex I deficiency induces drought tolerance by impacting leaf stomatal and hydraulic conductances.

To investigate the role of plant mitochondria in drought tolerance, the response to water deprivation was compared between Nicotiana sylvestris wild type (WT) plants and the CMSII respiratory complex I mutant, which has low-efficient respiration and photosynthesis, high levels of amino acids and pyridine nucleotides, and increased antioxidant capacity. We show that the delayed decrease in relative water content after water withholding in CMSII, as compared to WT leaves, is due to a lower stomatal conductance. The stomatal index and the abscisic acid (ABA) content were unaffected in well-watered mutant leaves, but the ABA/stomatal conductance relation was altered during drought, indicating that specific factors interact with ABA signalling.

Evidence that norflurazon affects chloroplast lipid unsaturation in soybean leaves (Glycine max L.).

Norflurazon is a bleaching herbicide known to block carotenoid biosynthesis by inhibiting phytoene desaturase activity. Soybean plants were treated with norflurazon, and we examined the effects on the desaturation of lipid molecular species in leaves using ammonium [1-(14)C] oleate labeling. In monogalactosyldiacylglycerol (MGDG), the main chloroplast lipid, a decrease in 18:3/18:3 molecular species and an increase in its precursors 18:2/18:3 and 18:2/18:2 were observed suggesting that the omega(3) FAD7 desaturase activity in planta was inhibited by norflurazon.

Sethoxydim affects lipid synthesis and acetyl-CoA carboxylase activity in soybean.

With rare exceptions, dicot plastids have been reported to contain only a multisubunit (prokaryotic) form of acetyl-coA carboxylase (ACCase), the first committed step of lipid biosynthesis. The sensitivity of most monocots to cyclohexanediones (CHDs) such as sethoxydim, has been shown to be associated with the presence in their plastids of a multifunctional (eukaryotic) form of ACCase. Little is known about the effects of sethoxydim on lipid metabolism and ACCase activity in dicots.

Desaturase mutants reveal that membrane rigidification acts as a cold perception mechanism upstream of the diacylglycerol kinase pathway in Arabidopsis cells.

Membrane rigidification could be the first step of cold perception in poikilotherms. We have investigated its implication in diacylglycerol kinase (DAGK) activation by cold stress in suspension cells from Arabidopsis mutants altered in desaturase activities. By lateral diffusion assay, we showed that plasma membrane rigidification with temperature decrease was steeper in cells deficient in oleate desaturase than in wild type cells and in cells overexpressing linoleate desaturase.

Drought stress affects chloroplast lipid metabolism in rape (Brassica napus) leaves.

Rape (Brassica napus L. var. Bienvenue) is a 16:3 plant which contains predominantly prokaryotic species of monogalactosyldiacylglycerol i.