DNA‐binding specificity, transcriptional activation potential, and the rin mutation effect for the tomato fruit‐ripening regulator RIN

Abstract

SummaryThe RIN gene encodes a putative MADS box transcription factor that controls tomato fruit ripening, and its ripening inhibitor (rin) mutation yields non-ripening fruit. In this study, the molecular properties of RIN and the rin mutant protein were clarified. The results revealed that the RIN protein accumulates in ripening fruit specifically and is localized in the nucleus of the cell. In vitro studies revealed that RIN forms a stable homodimer that binds to MADS domain-specific DNA sites. Analysis of binding site selection experiments revealed that the consensus binding sites of RIN highly resemble those of the SEPALLATA (SEP) proteins, which are Arabidopsis MADS box proteins that control the identity of floral organs. RIN exhibited a transcriptionactivating function similar to that exhibited by the SEP proteins. These results indicate that RIN exhibits similar molecular functions to SEP proteins although they play distinctly different biological roles. In vivo assays revealed that RIN binds to the cis-element of LeACS2. Our results also revealed that the rin mutant protein accumulates in the mutant fruit and exhibits a DNA-binding activity similar to that exhibited by the wild-type protein, but has lost its transcription-activating function, which in turn would inhibit ripening in mutant fruit.

Transcriptional Regulation of the Ethylene Response Factor LeERF2 in the Expression of Ethylene Biosynthesis Genes Controls Ethylene Production in Tomato and Tobacco

“…Accumulated evidence shows that the expression of ACS and ACO is induced by various factors, including indole-3-acetic acid, physical injury, cytokinins, ABA, brassinosteroid, ethylene, and other forms of stress (Tsuchisaka and Theologis, 2004;Wang et al, 2005;Hansen et al, 2009). A growing number of studies have reported that multiple regulations are involved in the expression of ACS and ACO (Matarasso et al, 2005;Ito et al, 2008;Lin et al, 2008). For example, tomato LeCp is a dual-function protein that acts as a Cys protease in the cytoplasm and can be SUMO modified to enter the nucleus to directly activate the expression of tomato LeACS2 following attack by a pathogen (Matarasso et al, 2005).…”

“…Recently, Lin et al (2008) found that an HD-Zip homeobox protein, LeHB-1, can bind to the homeobox cis-elements of the tomato LeACO1 promoter and regulate the gene's expression in developing fruits (Lin et al, 2008). And the transcription factor RIN modulates the expression of LeACS2 by binding to the CArG motif in fruit ripening (Ito et al, 2008), indicating that transcriptional regulation plays a key role in ethylene biosynthesis.…”

The fading distinctions between classical patterns of ripening in climacteric and non-climacteric fruit and the ubiquity of ethylene—An overview

“…Reduced expression of tomato LeEIL genes by antisense technology modulates ethylene responses, including leaf epinasty, flower senescence and fruit ripening (Tieman et al 2001). Ito et al (2008) demonstrated that the ripening inhibitor (RIN protein) exhibits transactivator activity because it binds to the promoter region of LeACS2. Thus, part of the gradual increase in ethylene production as observed in tomato fruit lines where LeEIL genes were suppressed by RNA interference engineering (RiEIL) may be due to the direct up-regulation of the LeACS2 gene by RIN.…”

Banana MaMADS Transcription Factors Are Necessary for Fruit Ripening and Molecular Tools to Promote Shelf-Life and Food Security

“…Banana and tomato fruit exhibit climacteric (elevated) respiration and a surge in ethylene hormone production concomitant with ripening (Seymour, 1993;Klee and Giovannoni, 2011), and tomato genes necessary for ethylene production and climacteric respiration have been identified (Alexander and Grierson, 2002;Giovannoni, 2007;Pirrello et al, 2009). Among them are several MADS box genes: SlMADS-RIN of the SEPALLATA (SEP) E function clade (Vrebalov et al, 2002;Ito et al, 2008;Zhong et al, 2013); FRUIFULL (FUL1 and FUL2) homologs (Bemer et al, 2012;Shima et al, 2014); and TAGL1, an AGAMOUS (AG)-like MADS box gene necessary for both early fruit expansion and later ripening (Itkin et al, 2009;Vrebalov et al, 2009). The SlMADS-RIN protein interacts with additional MADS box proteins, including TAGL1 and SlTAGL11 (Leseberg et al, 2008) and the tomato FUL homologs FUL1 and FUL2, to execute ripening (Martel et al, 2011;Fujisawa et al, 2014).…”