Organ identity genes and modified patterns of flower development inGerbera hybrida(Asteraceae)

Abstract

SummaryWe have used Gerbera hybrida (the cultivated ornamental, gerbera) to investigate the molecular basis of flower development in Asteraceae, a family of flowering plants that have heteromorphic flowers and specialized floral organs. Flowers of the same genotype may differ in a number of parameters, including sex expression, symmetry, sympetaly and pigmentation. In order to study the role of organ identity determination in these phenomena we isolated and functionally analysed six MADS box genes from gerbera; these were shown by phylogenetic analysis to be orthologous to well characterized regulatory genes described from Arabidopsis and Antirrhinum. Expression analysis suggests that the two gerbera agamous orthologues, the globosa orthologue and one of the deficiens orthologues may have functional equivalency to their counterparts, participating in the C and B functions, respectively. However, the function of a second deficiens orthologue appears unrelated to the B function, and that of a squamosa orthologue seems distinct from squamosa as well as from the A function. The induction patterns of gerbera MADS box genes conform spatiotemporally to the multi-flowered, head-like inflorescence typical of Asteraceae. Furthermore, gerbera plants transgenic for the newly isolated MADS box genes shed light onto the mechanistic basis for some floral characteristics that are typical for Asteraceae. We can conclude, therefore, that the pappus bristles are sepals highly modified for seed dispersal, and that organ abortion in the female marginal flowers is dependent upon organ

Plant biotechnology for deeper understanding, wider use and further development of agricultural and horticultural crops

“…Many novel functions for these regulators have been detected using transgenic plants that show distinct phenotypes. The results emphasize the importance of using gerbera for comparative studies with other model species such as Arabidopsis thaliana (Yu et al 1999, Kotilainen et al 2000, Uimari et al 2004, Teeri et al 2006c. Recent studies have employed expressed sequence tag (EST) sequencing and cDNA microarrays for identification of new gene family members related to both secondary metabolism and flower development (Laitinen et al 2005).…”

Identification and Characterization of Four Chrysanthemum MADS-Box Genes, Belonging to the APETALA1/FRUITFULL and SEPALLATA3 Subfamilies

“…Nevertheless, molecular genetic information about the control of flower development is restricted to studies with Gerbera hybrida (Yu et al, 1999;Kotilainen et al, 1999;Kotilainen et al, 2000) and Helianthus annuus (Dezar et al, 2003). In chrysanthemum, which is also a member of the Compositae family, two types of flowers can be distinguished: marginal ray florets consisting of a single petal and two fused carpels, and disc florets possessing five fused petals and five stamens that are partly fused to the two carpels.…”

Floral Meristem Identity Genes Are Expressed during Tendril Development in Grapevine

“…However, when homologous genes from species other than Arabidopsis have been analyzed, differences-regarding expression patterns and mutant phenotypes-have been found that may reflect distinct roles from those described for the Arabidopsis genes. For instance, the lack of examples of A-function mutants in most angiosperms analyzed questions a general role of AP1-like genes as A-function genes (Huijser et al, 1992;Yu et al, 1999;Litt and Irish, 2003). Moreover, in monocots, SQUA-like genes do not seem to be always functional orthologs of their Arabidopsis counterparts, based on their relatively large number and expression patterns (Schmitz et al, 2000;Theissen et al, 2000;Yu and Goh, 2000;Gocal et al, 2001).…”