Expression of Arabidopsis SR-like splicing proteins confers salt tolerance to yeast and transgenic plants.
Searching for novel targets of salt toxicity in eukaryotic cells, we have screened an Arabidopsis thaliana cDNA library to isolate genes conferring increased tolerance to salt stress when expressed in the yeast Saccharomyces cerevisiae. Here we show that expression of the 'alternating arginine-rich' (or RS) domains of two different SR-like, putative splicing proteins from Arabidopsis allows yeast cells to tolerate higher lithium and sodium concentrations. Protection against salt stress appears to require the in vivo phosphorylation of these plant polypeptides, since the yeast SR protein kinase Sky1p, which was able to phosphorylate in vitro at least one of them, also proved to be essential for the observed salt tolerance phenotype. In addition, a clone encoding the U1A protein, a previously characterised Arabidopsis splicing factor, was also isolated in the screening. No significant decrease in the intracellular concentration of lithium was observed in yeast cells incubated in the presence of LiCl upon expression of any of the Arabidopsis proteins, suggesting that their effects are not mediated by the stimulation of ion transport. In support of the general significance of these data, we also show that the expression of the RS domain of one of the SR-like proteins in transgenic Arabidopsis plants increases their tolerance to LiCl and NaCl. These results point to an important role of pre-mRNA splicing and SR-like proteins in the salt tolerance of eukaryotic cells, offering a novel route to improve this important trait in crop plants.
Forment
Javier
J
Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia-C.S.I.C., Camino de Vera s/n, 46022 Valencia, Spain.
Naranjo
Miguel Angel
MA
Roldán
Marta
M
Serrano
Ramón
R
Vicente
Oscar
O
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D017343:Genes, Plant / Q000235:genetics; D006706:Homeostasis / Q000187:drug effects; D008969:Molecular Sequence Data; D010766:Phosphorylation; D030821:Plants, Genetically Modified; D011494:Protein Kinases / Q000378:metabolism; D012326:RNA Splicing; D000072260:RNA Splicing Factors; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000378:metabolism; D000068103:Serine-Arginine Splicing Factors; D012965:Sodium Chloride / Q000494:pharmacology*; D013997:Time Factors; D019076:Transgenes / Q000235:genetics; D014882:Water-Electrolyte Balance / Q000187:drug effects
D029681:Arabidopsis Proteins; D018076:DNA, Complementary; C473790:RCY1 protein, Arabidopsis; D000072260:RNA Splicing Factors; C473789:SRL1 protein, Arabidopsis; D000068103:Serine-Arginine Splicing Factors; D012965:Sodium Chloride; D011494:Protein Kinases