Characterization of genes controlling stamen identity and development in a parthenocarpic tomato mutant indicates a role for the DEFICIENS ortholog in the control of fruit set

Abstract

The development of the ovary into a fruit depends on pollination and fertilization. It has been proposed that the restriction of ovary growth before pollination is because of the stamens acting as negative regulators. Accordingly, the silencing of genes responsible for stamen identity has been correlated with parthenocarpy in different species. The tomato (Solanum lycopersicum L.) parthenocarpic fruit (pat) mutation associates autonomous ovary development with homeotic transformation of the anthers and aberrancy of ovules in the ovary. In this study, we tested the hypothesis that stamen aberrations and parthenocarpy in pat are driven by cues coming from the altered expression of class B MADS box genes. The data showed that the Pat locus is not allelic to either of the two tomato mutations putatively involved in the B function, stamenless (sl)-2 and pistillate (pi) or to genes encoding class B transcription factors. Whereas pat pi double mutants were not recovered because of tight linkage, pat sl-2 double mutants showed mainly epistatic effects. The developmental regulation of the Sl DEFICIENS (DEF) gene in the wild-type (WT) at anthesis as well as its differential transcription in the pat ovary suggest that it plays a role in the control of ovary growth. Accordingly, when compared with the WT, the gene was also differentially expressed in the parthenocarpic fruit-2 (pat-2) mutant, that is not allelic to pat and has normal ovule development. Altogether the results indicate that in tomato SlDEF plays a role in the control of ovary growth and that the pat mutation is located upstream of this regulatory cascade.

Transcriptional and hormonal regulation of petal and stamen development by STAMENLESS, the tomato (Solanum lycopersicum L.) orthologue to the B-class APETALA3 gene

“…4F). This pattern of TAP3 expression in WT flowers is similar to what has been previously reported (de Martino et al , 2006; Mazzucato et al , 2008). In sl-LA0269 inflorescences, TAP3 was weakly expressed in the sympodial and floral meristems, whereas in the young flower buds its transcripts were detected in the meristem domains giving rise to second- and third-whorl primordia (Fig.…”

“…Four B-class genes are known in tomato, the AP3 homologues TAP3 and TM6 and the PI homologues TPI and TPIB (Pnueli et al , 1991; Busi et al , 2003; de Martino et al , 2006; Mazzucato et al , 2008; Geuten and Irish, 2010). The SL locus has been suggested as the tomato orthologue of B-function DEF gene of Antirrhinum majus and AP3 of Arabidopsis (Gómez et al , 1999; Mazzucato et al , 2008).…”

“…Two PI homologues were also identified, namely Tomato PISTILLATA ( TPI ; de Martino et al , 2006) (syn. SlGLO2 ; Mazzucato et al , 2008) and Solanum lycopersicum GLOBOSA ( SlGLO ; Mazzucato et al , 2008) (syn. SlGLO1 , LePI , TPIB ; Leseberg et al , 2008; Geuten and Irish, 2010).…”

“…, 1999). Recently, the SL locus has been suggested to be the tomato orthologue of the B-function DEFICIENS ( DEF ) gene of Antirrhinum majus (Gómez et al , 1999; Mazzucato et al , 2008), although definitive evidence had not been provided to date. We confirm this orthologue’s role by showing that the sl mutations described in Primabel and LA0269 backgrounds correspond to different alleles of the SL locus, which was previously named TAP3 by de Martino et al.…”

MADS Box Transcript Amount is Affected by Ethylene during Abscission

“…This statement is especially valid for MADS box with a SEP motif [68]. On the other hand, the function of MADS box proteins with the AG and PIST motives are more conserved across species probably because they have undergone a limited number of duplication [69]. The fact that MdPIST transcripts were found only in seed at day 3, at day 7 transcripts were detected only by overexposure of the film, and the expression analysis in published literature [57] indicate a specific action of MdPIST during normal ovule development.…”