Article

Plant Molecular Biology

, Volume 39, Issue 4, pp 785-795

First online:

Enhanced expression and differential inducibility of soybean chalcone synthase genes by supplemental UV-B in dark-grown seedlings

  • Takeshi ShimizuAffiliated withPlant Breeding Laboratory, Faculty of Agriculture, Hirosaki University
  • , Shinji AkadaAffiliated withGene Research Center, Hirosaki University
  • , Mineo SendaAffiliated withGene Research Center, Hirosaki University
  • , Ryuji IshikawaAffiliated withPlant Breeding Laboratory, Faculty of Agriculture, Hirosaki University
  • , Takeo HaradaAffiliated withPlant Breeding Laboratory, Faculty of Agriculture, Hirosaki University
  • , Minoru NiizekiAffiliated withPlant Breeding Laboratory, Faculty of Agriculture, Hirosaki University
  • , Shyam K. DubeAffiliated withCenter for Agricultural Biotechnology, University of Maryland Biotechnology Institute

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Abstract

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.

UV-B soybean chalcone synthase gene expression