Cold-regulated cereal chloroplast late embryogenesis abundant-like proteins. Molecular characterization and functional analyses.
Cold acclimation and freezing tolerance are the result of complex interaction between low temperature, light, and photosystem II (PSII) excitation pressure. Previous results have shown that expression of the Wcs19 gene is correlated with PSII excitation pressure measured in vivo as the relative reduction state of PSII. Using cDNA library screening and data mining, we have identified three different groups of proteins, late embryogenesis abundant (LEA) 3-L1, LEA3-L2, and LEA3-L3, sharing identities with WCS19. These groups represent a new class of proteins in cereals related to group 3 LEA proteins. They share important characteristics such as a sorting signal that is predicted to target them to either the chloroplast or mitochondria and a C-terminal sequence that may be involved in oligomerization. The results of subcellular fractionation, immunolocalization by electron microscopy and the analyses of target sequences within the Wcs19 gene are consistent with the localization of WCS19 within the chloroplast stroma of wheat (Triticum aestivum) and rye (Secale cereale). Western analysis showed that the accumulation of chloroplastic LEA3-L2 proteins is correlated with the capacity of different wheat and rye cultivars to develop freezing tolerance. Arabidopsis was transformed with the Wcs19 gene and the transgenic plants showed a significant increase in their freezing tolerance. This increase was only evident in cold-acclimated plants. The putative function of this protein in the enhancement of freezing tolerance is discussed.
Département des Sciences biologiques, Université du Québec à Montréal, C.P. 8888 Succursale Centre-ville, Montréal, Québec, Canada H3C 3P8.
Christian
C
NDong
Jean
J
Danyluk
Kenneth E
KE
Wilson
Tessa
T
Pocock
Norman P A
NP
Huner
Fathey
F
Sarhan
D000064:Acclimatization / Q000235:genetics; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics; D002736:Chloroplasts / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D002874:Chromosome Mapping; D003080:Cold Temperature; D002523:Edible Grain / Q000196:embryology / Q000235:genetics* / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D001467:Hordeum / Q000196:embryology / Q000235:genetics / Q000502:physiology; D007150:Immunohistochemistry; D008027:Light; D008854:Microscopy, Electron; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism; D045332:Photosystem II Protein Complex; D018515:Plant Leaves / Q000648:ultrastructure; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D011487:Protein Conformation; D012434:Secale / Q000196:embryology / Q000235:genetics / Q000502:physiology; D012639:Seeds / Q000196:embryology / Q000235:genetics* / Q000502:physiology; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013997:Time Factors; D014908:Triticum / Q000196:embryology / Q000235:genetics / Q000502:physiology
D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; C083953:Wcs19 protein, Triticum aestivum; C066246:late embryogenesis abundant protein, plant