%0 Journal Article %J Curr Opin Plant Biol %D 2015 %T Alternative splicing in plants: directing traffic at the crossroads of adaptation and environmental stress. %A Filichkin, Sergei %A Priest, Henry D %A Megraw, Molly %A Mockler, Todd C %K Adaptation, Biological %K Alternative Splicing %K Circadian Clocks %K Plant Physiological Phenomena %K RNA, Plant %K Stress, Physiological %X

In recent years, high-throughput sequencing-based analysis of plant transcriptomes has suggested that up to ∼60% of plant gene loci encode alternatively spliced mature transcripts. These studies have also revealed that alternative splicing in plants can be regulated by cell type, developmental stage, the environment, and the circadian clock. Alternative splicing is coupled to RNA surveillance and processing mechanisms, including nonsense mediated decay. Recently, non-protein-coding transcripts have also been shown to undergo alternative splicing. These discoveries collectively describe a robust system of post-transcriptional regulatory feedback loops which influence RNA abundance. In this review, we summarize recent studies describing the specific roles alternative splicing and RNA surveillance play in plant adaptation to environmental stresses and the regulation of the circadian clock.

%B Curr Opin Plant Biol %V 24 %P 125-35 %8 2015 Apr %G eng %R 10.1016/j.pbi.2015.02.008 %0 Journal Article %J Development %D 2015 %T The cyclophilin A DIAGEOTROPICA gene affects auxin transport in both root and shoot to control lateral root formation. %A Ivanchenko, Maria G %A Zhu, Jinsheng %A Wang, Bangjun %A Medvecká, Eva %A Du, Yunlong %A Azzarello, Elisa %A Mancuso, Stefano %A Megraw, Molly %A Filichkin, Sergei %A Dubrovsky, Joseph G %A Friml, Jiří %A Geisler, Markus %K Arabidopsis %K Biological Transport %K Cyclophilin A %K Indoleacetic Acids %K Lycopersicon esculentum %K Plant Proteins %K Plant Roots %K Plant Shoots %X

Cyclophilin A is a conserved peptidyl-prolyl cis-trans isomerase (PPIase) best known as the cellular receptor of the immunosuppressant cyclosporine A. Despite significant effort, evidence of developmental functions of cyclophilin A in non-plant systems has remained obscure. Mutations in a tomato (Solanum lycopersicum) cyclophilin A ortholog, DIAGEOTROPICA (DGT), have been shown to abolish the organogenesis of lateral roots; however, a mechanistic explanation of the phenotype is lacking. Here, we show that the dgt mutant lacks auxin maxima relevant to priming and specification of lateral root founder cells. DGT is expressed in shoot and root, and localizes to both the nucleus and cytoplasm during lateral root organogenesis. Mutation of ENTIRE/IAA9, a member of the auxin-responsive Aux/IAA protein family of transcriptional repressors, partially restores the inability of dgt to initiate lateral root primordia but not the primordia outgrowth. By comparison, grafting of a wild-type scion restores the process of lateral root formation, consistent with participation of a mobile signal. Antibodies do not detect movement of the DGT protein into the dgt rootstock; however, experiments with radiolabeled auxin and an auxin-specific microelectrode demonstrate abnormal auxin fluxes. Functional studies of DGT in heterologous yeast and tobacco-leaf auxin-transport systems demonstrate that DGT negatively regulates PIN-FORMED (PIN) auxin efflux transporters by affecting their plasma membrane localization. Studies in tomato support complex effects of the dgt mutation on PIN expression level, expression domain and plasma membrane localization. Our data demonstrate that DGT regulates auxin transport in lateral root formation.

%B Development %V 142 %P 712-21 %8 2015 Feb 15 %G eng %N 4 %R 10.1242/dev.113225