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. 2000 Aug 29;97(19):10637–10642. doi: 10.1073/pnas.170292997

Figure 2.

Figure 2

FIS2, MEA, and FIE∷GUS fusion activity and imprinting. (i) FIS2, MEA, and FIE∷GUS fusion activity. (A–H) FIS2∷GUS activity. (A and B) Unpollinated ovules showing GUS activity in the central cell nucleus. (C–F) Free endosperm nuclei divide from 2 to 32. (G) Nuclei in cyst region retaining GUS activity. (H) Synergids and possible egg nuclei showing GUS activity. (I–L) MEA∷GUS activity. (I) Unpollinated ovule showing GUS activity in the central cell nucleus. (J and K) MEA∷GUS activity in dividing endosperm nuclei. (L) Nuclei in cyst region retaining GUS activity. (M–Q) FIE∷GUS activity. (M) Microspores showing transient GUS activity. (N) Unpollinated ovule showing GUS activity. The central cell region is dense. (O) Ovule 24 h after pollination, showing diffuse GUS activity. (P and Q) Seven-day-old seed dissected to stain embryo and rest of the seed separately, showing the GUS activity in embryo and inside the seed coat. (ii) FIS2, MEA, and FIE imprinting. (A) Twenty-four-hour-old ovule with maternally derived FIS2∷GUS, showing GUS activity. (B) Twenty-four-hour-old ovule pollinated with a FIS2∷GUS plant, showing no GUS activity. (C) Twenty-four-hour-old ovule pollinated with a MEA∷GUS plant, showing no GUS activity. (D) Forty-eight-hour-old ovule showing GUS activity in cyst and possibly in embryo after pollination with MEA∷GUS. (E) No GUS activity seen in an Landsberg erecta (L.er) ovule pollinated with FIE∷GUS 48 h after pollination. (F) Endosperm and heart stage embryo showing GUS activity in an ovule pollinated by a FIE∷GUS plant 4 days after pollination. (Bars = 0.05 mm.)