Characterization of cDNAs representing five abscisic acid-responsive genes associated with somatic embryogenesis in Picea glauca, and their responses to abscisic acid stereostructure
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- Dong, JZ. & Dunstan, D. Planta (1997) 203: 448. doi:10.1007/s004250050213
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Five abscisic acid (ABA)-responsive cDNAs that were identified by differential screening of a white spruce [Picea glauca (Moench) Voss] cotyledonary somatic embryo cDNA library are characterized. Three of the cDNAs (PgEMB12, 14, 15) are predicted to encode homologues of different late-embryogenesis-abundant (LEA) proteins, a further two (PgEMB 5 and 23) share little similarity to any known DNA or protein sequences. When suspension cultures were fed 1.5 × 105 M S-(+)-ABA and assessed for transcript abundance over 48 h, gene expression corresponding to each lea-like gene was inducible and was evident during the 48-h period. Conversely, transcripts were at a very low abundance when suspensions were fed R-(−)-ABA. When suspensions were treated with a range of S-(+)-ABA and R-(−)-ABA concentrations (10−7–10−4 M), expression was induced at S-(+)-ABA concentrations of 10−5 M or above. Expression corresponding to PgEMB5 and PgEMB23 indicates less specificity for ABA stereostructure, with similar expression patterns being observed for either enantiomer during the 48 h after feeding. The two corresponding genes also appear more responsive to ABA concentration than the predicted lea genes, within the range examined (10−7–10−4 M).