MAP kinases in ovule development: Functional analysis of MPK3 & 6 promoters [abstract]
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Mitogen-activated protein kinase (MAPK) cascades are major pathways involved in signal transduction. A MAPK cascade consists of three kinases; MAPK, MAPK kinase (MAPKK) and MAPKK kinase (MAPKKK). Upon activation by a receptor/sensor, MAPKKK phosphorylates MAPKK, which in turn phosphorylates MAPK and activates it (Chang and Karin, 2001; Widmann et al., 1999). Of the nearly 20 MAPKs identified in the fully sequenced Arabidopsis genome, MPK3 and MPK6 are the most similar (Ichimura et al., 2002; Jonak et al., 2002; Tena et al., 2001; Zhang and Klessig, 2001). MPK3 and MPK6 have been found to exhibit overlapping functions (Wang 2006). While MPK3/MPK6 single mutants and MPK3-/-/MPK6+/- plants exhibited normal phenotype, MPK3+/-/MPK6-/- plants were female sterile and double mutants were embryo lethal. In order to rescue the MPK3+/-/MPK6-/- phenotype, we used a technique of "promoter swapping," with the promoter of MPK3 paired with MPK3 or MPK6 cDNA and vice versa. We were able to fully or partially rescue MPK3+/-/MPK6-/- plants with each combination. Now that we know the promoter-swapped transgene can rescue the plants, a green fluorescent protein (GFP) marker can be added to the gene in order to tell where and when in development the MPK3 or MPK6 promoter is activated.