Soybean of Williams and Forrest varieties were grown several ways, depending on the experiment. Studies where germinating seeds were treated with UV radiation (on Day 3), 30 seeds were planted (Day 0) on 0.8% agarose plates containing only 0.5 X Murashige and Skoog media as described in Lapik and Kaufman (2003). Soybean lie no deeper than 2 mm below the surface of agarose media.
Seedlings were grown in complete darkness for a various number of days, as described in the experiments (20 seeds planted, then utilized for 5 days after irradiation for fresh weight, ~100 seeds planted, grown for 7 days then irradiated for metabolome). Germinating seedlings were irradiated with a single pulse of 1,260 s or less (e.g., 1,260 s irradiation period for 300 nm; 1,080 s for 317 nm;
240 s for 368 nm) of low fluence UV (total fluence of 10 ^mol m ; as measured by UV-A, UV-B monitor, (Warpeha and Kaufman, 1990; Warpeha et al., 1991; Warpeha et al., 2008)) or Untreated (no UV), on the third day after planting, or the seventh day after planting (the latter, metabolome studies only). Fluence levels used have been confirmed to be within reciprocity limits for BL/UV-A (Warpeha and Kaufman, 1990). Seedlings were placed back in the dark for times as indicated in experiments in the phytatrays.
Experiments for growth and viability were conducted on seedlings that were transplanted to soil on Day 3 and maintained in growth chambers (14:10) after which they were followed out for 28 days or 10 days, respectively (about 20 plants in each replicate). Plants assessed for yield were grown outdoors (20 - 30 plants) in soil from Day 3 until seed sets where pods were harvested and seed visually analyzed.
For fresh weight studies, the first set of developing leaves were harvested (Warpeha et al., 1991) from 20 seedlings. For metabolome studies, primary leaves were harvested from soybean grown in phytatrays and maintained in darkness aside from indicated irradiations (~20 plants per replicate).
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