Expressional diversity of wheat nsLTP genes: evidence of subfunctionalization via cis-regulatory divergence.
Previously, the wheat non-specific lipid transfer proteins (TaLTP), members of a small multigene family, were reported to evidence a complex pattern of expression regulation. In order to assess further the expression diversity of the TaLTP genes, we have attempted to evaluate their expression profiles in responses to abiotic stresses, using semi-quantitative RT-PCR. The expression profiles generated herein revealed that the TaLTP genes in group A evidenced highly similar responses against abiotic stresses, whereas differential expression patterns among genes in each group were also observed. A total of seven promoters were fused to a GUS reporter gene and the recombinants were introduced into Arabidopsis, while three promoters evidenced non-detectible GUS activity. The promoters of TaLTP1, TaLTP7, and TaLTP10 included in group A drove strong expressions during plant development with overlapping patterns, in large part, but also exhibited distinct expression pattern, thereby suggesting subfunctionalization processing over evolutionary time. However, only trace expression in cotyledons, young emerged leaves, and epidermal cell layers of flower ovaries was driven by the promoter of TaLTP3 of group B. These results indicate that their distinct physiological functions appear to be accomplished by a subfunctionalization process involving degenerative mutations in regulatory regions.
Division of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul 136-713, Korea.
Hong Wei
HW
Wang
Hyuk Jin
HJ
Kwon
Won Cheol
WC
Yim
Sung Don
SD
Lim
Jun-Cheol
JC
Moon
Byung-Moo
BM
Lee
Yong Weon
YW
Seo
Wook
W
Kim
Cheol Seong
CS
Jang
D017360:Arabidopsis / Q000235:genetics; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics*; D019143:Evolution, Molecular; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics*; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013312:Stress, Physiological / Q000235:genetics; D014908:Triticum / Q000235:genetics* / Q000502:physiology
D002352:Carrier Proteins; D010940:Plant Proteins; C030363:lipid transfer protein