ATFL1 (Anti-TFL1), a novel orthologue induces flowering in the masting alpine snow tussock, Chionochloa pallens (Poaceae)

Masting, the synchronous highly variable flowering across years by a population of perennial plants, has been shown to be precipitated by many factors including nitrogen levels, drought conditions, spring and summer temperatures. However, the molecular mechanism leading to the initiation of flowering in masting plants in particular years remains largely unknown, despite the potential impact of climate change on masting phenology. We studied genes controlling flowering in Chionochloa pallens, a strongly masting perennial grass. We used a range of in situ and manipulated plants to obtain leaf samples from tillers (shoots) which subsequently remained vegetative or flowered. Here, we show that a novel orthologue of TERMINAL FLOWER 1 (TFL1; normally a repressor of flowering in other species) promotes the induction of flowering in C. pallens (hence Anti-TFL1), a conclusion supported by structural, functional and expression analyses. Global transcriptomic analysis indicated differential expression of CpTPS1, CpGA20ox1, CpREF6 and CpHDA6, emphasising the role of endogenous cues and epigenetic regulation in terms of responsiveness of plants to initiate flowering. Our molecular-based study has provided insights into the cellular mechanism of flowering in masting plants and will supplement ecological and statistical models to predict how masting will respond to global climate change.

OsSPL9 Regulates Grain Number and Grain Yield in Rice

Rice grain yield consists of several key components, including tiller number, grain number per panicle (GNP), and grain weight. Among them, GNP is mainly determined by panicle branches and spikelet formation. In this study, we identified a gene affecting GNP and grain yield, OsSPL9, which encodes SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE (SPL) family proteins. The mutation of OsSPL9 significantly reduced secondary branches and GNP. OsSPL9 was highly expressed in the early developing young panicles, consistent with its function of regulating panicle development. By combining expression analysis and dual-luciferase assays, we further confirmed that OsSPL9 directly activates the expression of RCN1 (rice TERMINAL FLOWER 1/CENTRORADIALIS homolog) in the early developing young panicle to regulate the panicle branches and GNP. Haplotype analysis showed that Hap3 and Hap4 of OsSPL9 might be favorable haplotypes contributing to high GNP in rice. These results provide new insights on high grain number breeding in rice.

The Branchless Gene C lbl in Watermelon Encoding a Terminal Flower 1 Protein Regulate S the Number of Lateral Branch

Lateral branching is one of the most important traits, which directly determines plant 27 architecture and crop productivity. Commercial watermelon has the characteristics of multiple 28 lateral branches, and it is time-consuming and labor costing to manually remove the lateral 29 branches in traditional watermelon cultivation. In our present study, a lateral branchless trait was 30 identified in watermelon material W CZ, and genetic analysis revealed that it was controlled by a 31 single recessive gene, which named as Clbl . A bulked segregant sequencing (BSA seq) and 32 linkage analysis was conducted to primarily mapping of Clbl on watermelon chromosome 4 33 Next-generation sequencing aided marker discovery and a large mapping population consisting of 34 1406 F 2 plants was used to further mapped the Clbl locus into a 9011 bp candidate region which 35 harbored only one candidate gene Cla018392 encoding a TERMINAL FLOWER 1 gene. Sequence 36 comparison of Cla018392 between two parental lines revealed that there was a SNP detected from 37 C to A in the coding region in the branchless inbred line WCZ , which resulted in a mutation of 38 Alanine (GCA) to Glutamate (GAA) at the fourth exon A dCAPS marker was developed from the 39 SNP locus, which was co-segregated with the branchless phenotype in both BC 1 and F 2 population, 40 and it was also further validated in 152 natural watermelon accessions. qRT PCR and in situ 41 hybridization showed that the expression levels of Cla0 18392 was significantly reduced in the 42 axillary bud and apical bud in the branchless line WCZ Ectopic expression of ClTFL1 in 43 Arabidopsis showed an increased number of lateral branches. The results of this study will be 44 useful for better understanding the molecular mechanism of lateral branch development in 45 watermelon and for the development of marker-assisted selection (MAS) for new branchless 46 watermelon cultivars.

DOTFL1 affects the floral transition in orchid Dendrobium Chao Praya Smile

A major obstacle for orchid (Orchidaceae)breeding and production is a long juvenile phase before orchid reproductive development. The molecular basis for prolonged vegetative growth in orchids remains largely unclear despite many efforts to clarify the relevant mechanisms. In this study, we report functional characterization of Dendrobium Orchid TERMINAL FLOWER1 (DOTFL1), an ortholog of TFL1 in Arabidopsis (Arabidopsis thaliana), from the orchid Dendrobium Chao Praya Smile. DOTFL1 is highly expressed in pseudobulbs and the shoot apical meristem (SAM) before and during the floral transition, but is downregulated in inflorescence apices and open flowers. Ectopic expression of DOTFL1 rescues the early-flowering and terminal-flower phenotypes of tfl1-20 in Arabidopsis. Overexpression of DOTFL1 in Dendrobium orchids delays flowering and produces defective inflorescence meristems and flowers with vegetative traits, whereas knockdown of DOTFL1 accelerates flowering and perturbs the maintenance of the inflorescence meristem. Notably, DOTFL1 suppresses orchid flowering and associated pseudobulb formation during the floral transition. We further reveal that two orchid MADS-box transcription factors, Dendrobium Orchid SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (DOSOC1) and AGAMOUS-LIKE 24 (DOAGL24), could interact with each other and bind to the CArG-box motif at DOTFL1, implying a regulatory hierarchy similar to their counterparts in Arabidopsis. Taken together, our findings suggest that DOTFL1 promotes vegetative growth, modulates successive developmental events required for reproductive success in Dendrobium orchids, and may have evolved with a previously unknown role in controlling pseudobulb formation in the Orchidaceae family.

ATFL1 (Anti-TFL1), a novel orthologue induces flowering in the masting alpine snow tussock, Chionochloa pallens (Poaceae)

Masting, the synchronous highly variable flowering across years by a population of perennial plants, has been shown to be precipitated by many factors including nitrogen levels, drought conditions, spring and summer temperatures. However, the molecular mechanism leading to the initiation of flowering in masting plants in particular years remains largely unknown, despite the potential impact of climate change on masting phenology. We studied genes controlling flowering in Chionochloa pallens, a strongly masting perennial grass. We used a range of in situ and manipulated plants to obtain leaf samples from tillers (shoots) which subsequently remained vegetative or flowered. Here, we show that a novel orthologue of TERMINAL FLOWER 1 (TFL1; normally a repressor of flowering in other species) promotes the induction of flowering in C. pallens (hence Anti-TFL1), a conclusion supported by structural, functional and expression analyses. Global transcriptomic analysis indicated differential expression of CpTPS1, CpGA20ox1, CpREF6 and CpHDA6, emphasising the role of endogenous cues and epigenetic regulation in terms of responsiveness of plants to initiate flowering. Our molecular-based study has provided insights into the cellular mechanism of flowering in masting plants and will supplement ecological and statistical models to predict how masting will respond to global climate change.

ASSESSMENT OF TIMING OF BUD DIFFERENTIATION AND DEVELOPMENT STAGES OF FLOWER INFLORESCENCE IN BLACKBERRY (Rubus spp.) CULTIVARS IN NORTHERN TURKEY

Blackberry (Rubus spp.) production is attracting interest in Turkey’s northern part, but information on timing of bud differentiation and developmental stages of flower inflorescence on next season is limited. The objective of this study was to determine the timing of bud differentiation and development stages of flower inflorescence in 4 biennial fruiting blackberry (Rubus spp.) cultivars (‘Chester’, ‘Dirksen Thornless’, ‘Jumbo’, ‘Bursa 1’) grown in northern Turkey. Axillary bud samples were collected from the middle parts of the one year of lateral branches every 7–15 days from September 2008 to May 2010. Ten development stages were identified from the flower bud differentiation to post-bloom period. The transition from the vegetative to reproductive stage occurred during September to October, with the differentiation of the terminal flower occurring on September 18 in ‘Bursa 1’, October 4–9 in ‘Dirksen Thornless’, October 16–20 in ‘Jumbo’, and October 20–22 in ‘Chester’. In all the examined cultivars, flower development occurred between September and June and lasted for 193–215 days.

TERMINAL FLOWER 1-FD complex target genes and competition with FLOWERING LOCUS T

Plants monitor seasonal cues to optimize reproductive success by tuning onset of reproduction and inflorescence architecture. TERMINAL FLOWER 1 (TFL1) and FLOWERING LOCUS T (FT) and their orthologs antagonistically regulate these life history traits, yet their mechanism of action, antagonism and targets remain poorly understood. Here, we show that TFL1 is recruited to thousands of loci by the bZIP transcription factor FD. We identify the master regulator of floral fate, LEAFY (LFY) as a target under dual opposite regulation by TFL1 and FT and uncover a pivotal role of FT in promoting flower fate via LFY upregulation. We provide evidence that the antagonism between FT and TFL1 relies on competition for chromatin-bound FD at shared target loci. Direct TFL1-FD regulated target genes identify this complex as a hub for repressing both master regulators of reproductive development and endogenous signalling pathways. Our data provide mechanistic insight into how TFL1-FD sculpt inflorescence architecture, a trait important for reproductive success, plant architecture and yield.