Plant MADS box genes, including 6 new sequences from Gerbera (Asteraceae)

Data: Alignment of 72 plant MADS box genes for their MADS and K boxes. GENBANK accession numbers are indicated after each taxon name in the matrix. Gaps are indicated with "-".

Matrix type: Parsimony jackknife format, text-only.

Reference: Yu, D., M. Kotilainen, E. Pöllänen, M. Mehto, P. Elomaa, Y. Helariutta, V. A. Albert, and T. H. Teeri. 1999. Organ identity genes and modified patterns of flower development in Gerbera hybrida, Asteraceae. Plant Journal 17: 51-62.

Summary of results: Gerbera hybrida (the cultivated ornamental, gerbera) has been used to investigate the molecular basis of flower development in the Asteraceae, which bear heteromorphic flowers with specialized floral organs on condensed inflorescences (capitula). Within a single genotype, gerbera flowers may vary in a number of parameters, including sex expression, symmetry, sympetaly, and pigmentation. In order to evaluate the role of determination of organ identity in these features, six MADS box genes from gerbera were isolated and functionally analyzed. Phylogenetic analysis showed these genes to be orthologous to well-known regulatory genes described from Arabidopsis and Antirrhinum. Gene expression studies suggested that the two gerbera AGAMOUS orthologues, the GLOBOSA orthologue and one of the DEFICIENS orthologues may be functionally equivalent to their counterparts, taking part in the C and B functions, respectively. A second DEFICIENS orthologue, however, appears to have a function unrelated to B class genes, and a SQUAMOSA orthologue appears functionally unrelated to SQUAMOSA and the A function. The patterns of induction of the gerbera MADS box genes are spatiotemporally correlated with flower induction on the head-like capitulum. Transgenic gerbera plants that either over- or under-express the newly isolated MADS box genes led to new insights on Asteraceae development and evolution: (1) it could be concluded that pappus bristles are sepals highly modified for seed dispersal, and (2) that organ abortion in the marginal, female flowers is dependent upon organ identity and not organ position, when organ position is altered homeotically.

Contact persons: Mika Kotilainen, Victor A. Albert

Date posted on WWW: 03/22/99

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