Ectopic expression of Arabidopsis FD and FD PARALOGUE in rice results in dwarfism with size reduction of spikelets

Abstract

Key flowering genes, FD and FD PARALOGUE (FDP) encoding bZIP transcription factors that interact with a FLOWERING LOCUS T (FT) in Arabidopsis were ectopically expressed in rice since we found AtFD and AtFDP also interact with HEADING DATE 3a (Hd3a) and RICE FLOWERING LOCUS T 1 (RFT1). Transgenic rice plants overexpressing AtFD and AtFDP caused reduction in plant height and spikelet size with decreased expression of genes involved in cell elongation without significant flowering time alteration in spite of increased expression of OsMADS14 and OsMADS15, rice homologues of APETALA1 (AP1) in the leaves. Simultaneous overexpression of AtFD and AtFDP enhanced phenotypes seen with overexpression of either single gene while transgenic rice plants expressing AtFD or AtFDP under the control of phloem-specific Hd3a promoter were indistinguishable from wild-type rice. Candidate genes responsible for the phenotypes were identified by comparison of microarray hybridization and their expression pattern was also examined in WT and transgenic rice plants. It has so far not been reported that AtFD and AtFDP affect cell elongation in plants, and our findings provide novel insight into the possible roles of AtFD and AtFDP in the mesophyll cells of plants, and potential genetic tools for manipulation of crop architecture.

Antagonistic Transcription Factor Complexes Modulate the Floral Transition in Rice

“…Similar interactions take place in many plant species, including tomato (Solanum lycopersicum; Park et al, 2014), potato (Solanum tuberosum; Teo et al, 2017), wheat (Triticum aestivum) and barley (Hordeum vulgare; Li et al, 2015), maize (Zea mays; Danilevskaya et al, 2008), and ½AQ2 hybrid aspen (Tylewicz et al, 2015), suggesting that this molecular module is widely conserved among angiosperms. This conservation is further corroborated by interspecific interactions demonstrated to occur between Hd3a/RFT1 and FD (Jang et al, 2017). In many such examples, FD-like genes can provide DNA binding specificity by recognizing ACGT-containing consensus sequences on the DNA of target promoters (Izawa et al, 1993;Li and Dubcovsky, 2008;Taoka et al, 2011;Wigge et al, 2005).…”

“…We excluded from this analysis OsbZIP29 as we could not amplify it from cDNA of LD-or SD-grown plants, bZIP54/OsFD6 as it is inferred to be a pseudogene (Tsuji et al, 2013), and finally genes whose interaction patterns have already been determined (Tsuji et al, 2013). The OsbZIP24/OsFD3 and OsbZIP69/OsFD4 proteins could not interact in our yeast assay with Hd3a or RFT1, although a recent report indicates weak interaction with RFT1 (Jang et al, 2017). OsbZIP24/OsFD3 could interact with Gf14c, while OsbZIP69/OsFD4 could not.…”

Short Panicle 3 controls panicle architecture by upregulating APO2/RFL and increasing cytokinin content in rice

“…Although SP3 overexpression plants had longer panicles and more spikelets per panicle, a lack of an increase in grain yield was due to a lower seed setting rate (Figure S9). This lower seed setting rate might result from ectopic expression of SP3 because ectopic expression can frequently cause pleiotropic phenotypic changes (Sakamoto et al ; Bai et al ; Jang et al ; Lu et al ).…”

Environmental Signal-Dependent Regulation of Flowering Time in Rice

“…Further studies are needed to determine whether SAPK10 also phosphorylates OsFD1/OsbZIP77 in vivo and whether this phosphorylation alters the activity of OsFD1/OsbZIP77 [ 78 ]. Similar to OsFD1/OsbZIP77, OsbZIP72, a positive regulator of ABA responses and drought tolerance in rice [ 79 ], formed a complex with Hd3a, RFT1, and GF14c when heterologously expressed in yeast [ 83 ]. However, the contribution of these proteins to flowering time regulation under drought stress is not clearly understood.…”