Interaction study of MADS-domain proteins in tomato

Abstract

MADS-domain proteins are important transcription factors involved in many biological processes of plants. Interactions between MADS-domain proteins are essential for their functions. In tomato (Solanum lycopersicum), the number of MIKC(c)-type MADS-domain proteins identified has totalled 36, but a large-scale interaction assay is lacking. In this study, 22 tomato MADS-domain proteins were selected from six functionally important subfamilies of the MADS-box gene family, to create the first large-scale tomato protein interaction network. Compared with Arabidopsis and petunia (Petunia hybrida), protein interaction patterns in tomato displayed both conservation and divergence. The majority of proteins that can be identified as putative orthologues exhibited conserved interaction patterns, and modifications were mostly found in genes underlining traits unique to tomato. JOINTLESS and RIN, characterized for their roles in abscission zone development and fruit ripening, respectively, showed enlarged interaction networks in comparison with their Arabidopsis and petunia counterparts. Novel interactions were also found for members of the expanded subfamilies, such as those represented by AP1/FUL and AP3/PI MADS-domain proteins. In search for higher order complexes, TM5 was found to be the preferred bridge among the five SEP-like proteins. Additionally, 16 proteins with the MADS-domain removed were used to assess the role of the MADS-domain in protein-protein interactions. The current work provides important knowledge for further functional and evolutionary study of the MADS-box genes in tomato.

The Tomato FRUITFULL Homologs TDR4/FUL1 and MBP7/FUL2 Regulate Ethylene-Independent Aspects of Fruit Ripening

“…However, although TAGL1 and FUL1/2 all play important roles in fruit ripening (Itkin et al, 2009;Vrebalov et al, 2009;Pan et al, 2010), they regulate different subsets of RIN target genes (Table 1; see Supplemental Data Set 1 online; Itkin et al, 2009;Vrebalov et al, 2009;Fujisawa et al, 2012), and the phenotypes of the TAGL1 and FUL1/2 silenced lines are distinctly different. Moreover, Leseberg et al (2008) did not identify interactions between TAGL1 and FUL1/2 in yeast two-hybrid or three-hybrid assays. This all suggests that TAGL1-RIN and FUL1/2-RIN form separate complexes with distinct functions in tomato fruit ripening.…”

“…RIN can heterodimerize with FUL1 and FUL2 in yeast (Leseberg et al, 2008), suggesting that both FUL homologs may function in the ripening process as interaction partners of RIN. To obtain more evidence for the existence of RIN-FUL1 and RIN-FUL2 heterodimers in planta, we tested the interactions in vivo in Arabidopsis protoplasts using split-yellow fluorescent protein (YFP) (Walter et al, 2004).…”

“…Different studies have reported that the ripening regulator RIN interacts in yeast with TAGL1, FUL1, and FUL2 (Leseberg et al, 2008;Martel et al, 2011). Because MADS domain proteins often act in higher order complexes (Immink et al, 2009), it is possible that FUL1/2, TAGL1, and RIN interact with each other in a higher order complex to mediate tomato fruit ripening.…”

“…Identification of these complexes and dissection of the function of RIN depends on the functional analysis of the interacting MADS box factors that are expressed in the fruit. The MADS domain proteins TOMATO AGAMOUS-LIKE1 (TAGL1), TAGL11, FUL1 (previously TDR4), and FUL2 (previously MBP7) were found to all interact with RIN (Leseberg et al, 2008;Martel et al, 2011) and to be present in ripening fruits (Hileman et al, 2006) and are thus candidates to mediate ripening processes together with RIN. Moreover, the binding of RIN to its target promoters was shown to be dependent on CNR activity, suggesting that CNR or one of its targets is required in a functional complex with RIN (Martel et al, 2011).…”

Deciphering the Physalis floridana Double-Layered-Lantern1 Mutant Provides Insights into Functional Divergence of the GLOBOSA Duplicates within the Solanaceae

“…PFSEP3, a SEPALLATA-like protein, is required for normal floral organ development (Pelaz et al, 2000;Immink et al, 2009). However, the direct interactions between B-class proteins and E-class (PFSEP3) proteins were observed in tomato (Solanum lycopersicum) but not in Arabidopsis, Antirrhinum majus, Petunia hybrida, or Eschscholzia californica (Davies et al, 1996;Vandenbussche et al, 2004;de Folter et al, 2005;de Martino et al, 2006;Leseberg et al, 2008;Lange et al, 2013), indicating that the dimerization pattern of the homeotic orthologous proteins is variable among angiosperms. However, our findings on protein-protein interactions provide a common basis underlying the role of PFGLO1 and PFGLO2 in floral development in Physalis floridana.…”