Rice Genetics IV - IRRI books - International Rice Research Institute

RBcis-effect of the adjacent strong enhancer of theduplicated 35S promoter on the Ac promoterd35S AcsGFP HygLBVery early transposition in all independent linesLinePlant1 2A 4A 4B 5 71 3 8 9 10 11 1 3 7 9 1011 1213 1 2 3 4 58 kb6 kb4 kb2 kbAc copy numberamplificationAc copy numberamplificationGene mutation machineFig. 1. Early transposition and amplification of autonomous Ac. The d35S-sGFP::Acconstruct with a duplicate CaMV 35S enhancer-promoter adjacent to the Ac promoter(shown by arrow). On excision, the sGFP expression can be visualized bygreen fluorescent protein (GFP) fluorescence. Shown below is DNA blot hybridizationof individual regenerants from six different transformed lines (as labeled),hybridized with an Ac-specific probe and fragment sizes given on left. All linesshowed very early transposition and the individual regenerants (e.g., 8, 9, 10,11) from line 2A (single T-DNA insert) display active transposition and amplification.Multiple Ac lines displaying independent transposition are used to make amutation machine for reverse genetics. RB = right border, LB = left border.influences transposase expression. The cis effect of the CaMV enhancer on the Acpromoter and transposase expression was observed earlier in Arabidopsis (Balcellsand Coupland 1994), leading to earlier excision of Ds.Ac reinsertion was evident in about 70% of the lines and one-third of these alsoshowed an amplification in Ac copy number as demonstrated by the number of Achybridizingfragments in the one- and two-copy Ac lines (lines 2A and 7 in Fig. 1).The process of transposition during replication has been described in maize (Greenblatt1984), in which Ac transposes from replicated DNA to unreplicated DNA, resultingin a moderate increase in copy number. In the amplifications we observed, the pres-Transposons and functional genomics in rice 269