Enhanced expression and differential inducibility of soybean chalcone synthase genes by supplemental UV-B in dark-grown seedlings.
By developing gene-specific RT-PCR and using filters to allow transmission down to 290 nm (UV-B+) or blocking all radiation below 320 nm (UV-B(-)), the effect of UV-B+ and UV-B- light on expression of each of the presently known seven members of soybean chalcone synthase (CHS) gene family in dark-grown seedlings was analyzed. Dark expression was detectable already in 18 h dark-germinating embryos, with progressive increases on successive days, suggesting that chs belongs to a class of genes expressed very early during germination, and that the expression at this stage is either constitutive or induced by non-light-dependent factors present in the seed or made available following imbibition. Exposure of 18 h dark-germinating embryos to UV-B- or to UV-B+ light did not lead to an increase in chs signal. However, the 24 h dark-germinating embryos showed a distinct effect of UV-B+, interestingly coinciding with the stage when the head of seedlings was in the process of being pushed up above ground by stem elongation, suggesting the possibility of a developmental switch modulating the appearance of UV-B response. The response to UV-B- was most prominent in chs1 and almost silent in chs2, while the up-regulation by UV-B+ was most prominent in chs5 and chs6 and much less so in chs2. Interestingly, chs2 was noted to be the only member of the Gmchs gene family devoid of H-box, raising the possibility that the H-box may be a good indicator of the photo-inducibility of a chs gene.
Shimizu
T
T
Plant Breeding Laboratory, Faculty of Agriculture, Hirosaki University, Japan.
Akada
S
S
Senda
M
M
Ishikawa
R
R
Harada
T
T
Niizeki
M
M
Dube
S K
SK
D000217:Acyltransferases / Q000096:biosynthesis / Q000235:genetics*; D001483:Base Sequence; D003624:Darkness; D004790:Enzyme Induction / Q000528:radiation effects; D015971:Gene Expression Regulation, Enzymologic / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects*; D017343:Genes, Plant; D007527:Isoenzymes / Q000096:biosynthesis / Q000235:genetics; D008969:Molecular Sequence Data; D005810:Multigene Family; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D013025:Glycine max / Q000201:enzymology* / Q000528:radiation effects; D014466:Ultraviolet Rays
D007527:Isoenzymes; D000217:Acyltransferases; C020141:flavanone synthetase