DIVERSE ROLES FOR MADS BOX GENES IN ARABIDOPSIS DEVELOPMENT

Members of the MADS box gene family play important roles in flower dev elopment from the early step of determining the identity of floral mer istems to specifying the identity of floral organ primordia later in f lower development. We describe here the isolation and characterization of six additional members of this family, increasing the number of re ported Arabidopsis MADS box genes to 17. All 11 members reported prior to this study are expressed in flowers, and the majority of them are floral specific. RNA expression analyses of the six genes reported her e indicate that two genes, AGL11 and AGL13 (AGL for AGAMOOS-like), are preferentially expressed in ovules, but each has a distinct expressio n pattern. AGL15 is preferentially expressed in embryos, with its onse t at or before the octant stage early in embryo development. AGL12, AG L14, and AGL17 are all preferentially expressed in root tissues and th erefore represent the only characterized MADS box genes expressed in r oots. Phylogenetic analyses showed that the two genes expressed in ovu les are closely related to previously isolated MADS box genes, whereas the four genes showing nonfloral expression are more distantly relate d. Data from this and previous studies indicate that in addition to th eir proven role in flower development, MADS box genes are likely to pl ay roles in many other aspects of plant development.