Flowering of strict photoperiodic Nicotiana varieties in non-inductive conditions by transgenic approaches

Abstract

The genus Nicotiana contains species and varieties that respond differently to photoperiod for flowering time control as day-neutral, short-day and long-day plants. In classical photoperiodism studies, these varieties have been widely used to analyse the physiological nature for floral induction by day length. Since key regulators for flowering time control by day length have been identified in Arabidopsis thaliana by molecular genetic studies, it was intriguing to analyse how closely related plants in the Nicotiana genus with opposite photoperiodic requirements respond to certain flowering time regulators. SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1) and FRUITFULL (FUL) are two MADS box genes that are involved in the regulation of flowering time in Arabidopsis. SOC1 is a central flowering time pathway integrator, whereas the exact role of FUL for floral induction has not been established yet. The putative Nicotiana orthologs of SOC1 and FUL, NtSOC1 and NtFUL, were studied in day-neutral tobacco Nicotiana tabacum cv Hicks, in short-day tobacco N. tabacum cv Hicks Maryland Mammoth (MM) and long-day N. sylvestris plants. Both genes were similarly expressed under short- and long-day conditions in day-neutral and short-day tobaccos, but showed a different expression pattern in N. sylvestris. Overexpression of NtSOC1 and NtFUL caused flowering either in strict short-day (NtSOC1) or long-day (NtFUL) Nicotiana varieties under non-inductive photoperiods, indicating that these genes might be limiting for floral induction under non-inductive conditions in different Nicotiana varieties.

A Change inSHATTERPROOFProtein Lies at the Origin of a Fruit Morphological Novelty and a New Strategy for Seed Dispersal inMedicagoGenus

“…3, A-C). Additional evidence obtained through functional studies in other distantly related species indicates that the role of the FUL/SHP network in fruit dehiscence and lignification is widely conserved, at least in dicot plants (Smykal et al, 2007;Fourquin and Ferrándiz, 2012;Pabón-Mora et al, 2012).…”

PoppyAPETALA1/FRUITFULLOrthologs Control Flowering Time, Branching, Perianth Identity, and Fruit Development

“…FUL plays a role in maintaining proper carpel wall growth during fruit development in Arabidopsis, and experiments overexpressing the euFUL gene DEFH28 from snapdragon in Arabidopsis (Mü ller et al, 2001) or silencing euFUL copies such as VmTR4 from bilberry (Vaccinium myrtillus; Jaakola et al, 2010) and Solanum lycopersicum MADS-box protein7 (SlMBP7) from tomato (R. Meyer, N. Pabó nMora, and A. Litt, unpublished data) suggest that other euFUL genes also play a role in fruit development. We have shown that FUL-like genes in Papaveraceae also play a role in proper fruit development similar to that of FUL and other euFUL genes, including ectopic lignification of the mesocarp (Gu et al, 1998;Mü ller et al, 2001;Smykal et al, 2007;Jaakola et al, 2010); this and other abnormalities could be responsible for premature rupture of the fruit wall. Thus, our data from Papaveraceae show that their FUL-like genes (1) function in proper floral meristem and sepal identity, similar to AP1 and other euAP1 genes, and (2) are required for proper fruit wall growth and cell differentiation, similar to euFUL genes.…”

“…In petunia (Petunia hybrida), silencing of PETUNIA FLOWERING GENE (PFG) resulted in plants that remained vegetative (Immink et al, 1999). Overexpression of an Antirrhinum euFUL paralog, DEFICIENS-homolog28 (DEFH28), in Arabidopsis (Mü ller et al, 2001) and of the Nicotiana tabacum FUL (NtFUL) in tobacco (Nicotiana tabacum; Smykal et al, 2007) resulted in fruits with defective lignification that failed to dehisce. These data suggest that other euFUL genes may have the same dual roles as FUL: an early role in promoting the transition to reproductive meristems and a late role in proper fruit development.…”

A Redox-Mediated Modulation of Stem Bolting in TransgenicNicotiana sylvestrisDifferentially Expressing the External Mitochondrial NADPH Dehydrogenase

“…We observed higher and lower transcript levels in the overexpressor and suppressor lines, respectively, for N. sylvestris MADS1 and MADS2 as well as a decrease of NFL2 in the suppressor line. NsMADS1 and NsMADS2 belong to the SQUAMOSA subfamily of floral meristem and organ identity proteins, including Arabidopsis APETALA1 (AP1; Becker and Theissen, 2003;Smykal et al, 2007). NsMADS1 is an ortholog to the floral transition marker NtMADS11 (Jang et al, 2002;Gallego-Giraldo et al, 2007).…”

“…AOX, Alternative oxidase; EFD, EF-hand domain; Etio., etiolated; Fl., flower; Mat., mature; Src., source; UCP, uncoupling protein. scriptionally induced in the stem apex during floral transition (Cho et al, 1999;Jang et al, 1999;Smykal et al, 2007). Thus, NsMADS2 has a central function for bolting and flowering induction in N. sylvestris, possibly similar to AP1 in Arabidopsis (He and Amasino, 2005).…”