Cold acclimation-induced WAP27 localized in endoplasmic reticulum in cortical parenchyma cells of mulberry tree was homologous to group 3 late-embryogenesis abundant proteins.
We have shown that two 27-kD proteins, designated as WAP27A and WAP27B, were abundantly accumulated in endoplasmic reticulum-enriched fractions isolated from cortical parenchyma cells of mulberry tree (Morus bombycis Koidz.) during winter (N. Ukaji, C. Kuwabara, D. Takezawa, K. Arakawa, S. Yoshida, S. Fujikawa [1999] Plant Physiol 120: 480--489). In the present study, cDNA clones encoding WAP27A and WAP27B were isolated and characterized. The deduced amino acid sequences of WAP27A and WAP27B cDNAs had 12 repeats of an 11-mer amino acid motif that was the common feature of group 3 late-embryogenesis-abundant proteins. Under field conditions, transcripts of WAP27 genes were initially detected in mid-October, reached maximum level from mid-November to mid-December, and then gradually decreased. The transcript levels of WAP27 genes in cortical parenchyma cells harvested in October was drastically induced by cold treatment within a few days, whereas those in cortical parenchyma cells harvested in August were low even by cold treatment for 3 weeks. Immunocytochemical analysis by electron microscopy confirmed that WAP27 was localized specifically in vesicular-form ER and also localized in dehydration-induced multiplex lamellae-form ER. The role of WAP27 in the ER is discussed in relation to acquisition of freezing tolerance of cortical parenchyma cells in mulberry tree during winter.
Ukaji
N
N
Graduate School of Agriculture, Hokkaido University, Sapporo 060-8589, Japan.
Kuwabara
C
C
Takezawa
D
D
Arakawa
K
K
Fujikawa
S
S
D000064:Acclimatization; D000595:Amino Acid Sequence; D003081:Cold Climate; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D018514:Plant Structures; D012333:RNA, Messenger / Q000378:metabolism; D018749:RNA, Plant / Q000378:metabolism; D019685:Rosales / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D012621:Seasons; D017386:Sequence Homology, Amino Acid; D014197:Trees / Q000166:cytology / Q000235:genetics / Q000378:metabolism*
D006360:Heat-Shock Proteins; C436295:MWAP27 protein, Morus bombycis; D010940:Plant Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; C066246:late embryogenesis abundant protein, plant