Suppression of SlMBP15 Inhibits Plant Vegetative Growth and Delays Fruit Ripening in Tomato

Abstract

MADS-box genes have been demonstrated to participate in a number of processes in tomato development, especially fruit ripening. In this study, we reported a novel MADS-box gene, SlMBP15, which is implicated in fruit ripening. Based on statistical analysis, the ripening time of SlMBP15-silenced tomato was delayed by 2–4 days compared with that of the wild-type (WT). The accumulation of carotenoids and biosynthesis of ethylene in fruits were decreased in SlMBP15-silenced tomato. Genes related to carotenoid and ethylene biosynthesis were greatly repressed. SlMBP15 can interact with RIN, a MADS-box regulator affecting the carotenoid accumulation and ethylene biosynthesis in tomato. In addition, SlMBP15-silenced tomato produced dark green leaves, and its plant height was reduced. The gibberellin (GA) content of transgenic plants was lower than that of the WT and GA biosynthesis genes were repressed. These results demonstrated that SlMBP15 not only positively regulated tomato fruit ripening but also affected the morphogenesis of the vegetative organs.

A critical evaluation of the role of ethylene and MADS transcription factors in the network controlling fleshy fruit ripening

“…This is puzzling, because the normal level of SlMBP15 transcripts shown in some databases is very low (Fig. ) (Yin et al ., ). TAG1 also has been reported to physically interact with MADS‐RIN and, as pointed out by Giovannoni et al .…”

“…There are 33 published MIKC‐MADS factors in the tomato genome (Jin et al ., ; Yin et al ., ), although it is possible that more may be identified. MADS‐RIN is the most highly expressed, but transcripts of around a dozen others can be detected in ripening tomatoes (Fig.…”

“…Manipulation of the expression of several of these genes in transgenic plants has been shown to alter ripening. Tomato RIN interacts with FUL1/FUL2 (Shima et al ., ), TAGL1 (Leseberg et al ., ), SlMBP18 (Yin et al ., ), and also can act as a SEP‐like protein bridging factor, generating higher‐order protein complexes with TFs including TM4 and SlMBP24, although these proteins do not themselves interact directly in a Yeast‐2‐Hybrid protein‐interaction test (Leseberg et al ., ). FUL1 and FUL2 are functionally redundant in fruit ripening regulation and dual suppression of both genes substantially inhibited ripening by blocking ethylene biosynthesis and decreasing carotenoid accumulation (S. F. Wang et al ., ).…”

“…Gene names: TAG 1 , Solyc02g071730 ; TAGL 1 , Solyc07g055920 ; AGL 11 , Solyc11g028020 ; TDR 8/ TM 8 , Solyc03g019710 ; JOINTLESS , Solyc11g010570 ; TAGL 12 , Solyc11g032100 ; Sl FYFL /Sl MBP 18 , Solyc03g006830 ; Sl MBP 11 , Solyc01g087990 ; TPI , Solyc06g059970; Def , Solyc04g081000 ; TDR 6/ TM 6 , Solyc02g084630 ; FUL 2/Sl MBP 7 , Solyc03g114830 ; FUL 1/ TDR 4/ TM 4 , Solyc06g069430 ; MC /Le AP 1 , Solyc05g056620 ; Sl MBP 20 , Solyc02g089210 ; Sl MBP 6 , Solyc01g093960 ; TM 29/ TAGL 2 , Solyc02g089200 ; TDR 5/ TM 5 , Solyc05g015750 ; Sl CMB 1 , Solyc04g005320 ; RIN , Solyc05g012020 ; MADS 1 , Solyc03g114840 ; SLMB 21 , Solyc12g038510 ; Sl MBP 8 , Solyc12g087830 ; Sl MBP 15 , Solyc12g087810 . (b) Reported physical interaction between MADS ‐ RIN and other MADS TF s expressed in ripening tomato: AGL 11 (Leseberg et al ., ; Huang et al ., ), Sl MBP 8 (Yin et al ., ), Sl MADS 1 (Dong et al ., ), Sl FYFL (Xie et al ., ), Sl CMB 1 (Zhang et al ., ), FUL 1/ FUL 2 (Fujisawa et al ., ), TAGL 1 (Leseberg et al ., ; Vrebalov et al ., ; Giménez et al ., ), Sl MBP 15 (Yin et al ., ), and interaction between NAC 4 and MADS ‐ RIN (Zhu et al ., ), AP 2a and Sl CMB 1 (Zhang et al ., ) are discussed in the text. Blue and red circles indicate repressors and activators, respectively.…”

“…If two MADS dimers bound at different sites in DNA come into close contact as a result of chromatin conformation, tetramerization also could occur, enabling the MADS TFs to act as a dynamic interaction network (Puranik et al, 2014), thus making it possible for multiple CArG boxes in the gene promoter regions of different genes to facilitate the formation of transcription factories (Sutherland & Bickmore, 2009). There are 33 published MIKC-MADS factors in the tomato genome (Jin et al, 2017;Yin et al, 2018), although it is possible that more may be identified. MADS-RIN is the most highly expressed, but transcripts of around a dozen others can be detected in ripening tomatoes (Fig.…”