Loss-of-function of StFKF1 delays flowering and tuberization under long-day conditions in potato

A mutant allele of the long-day floral activator NtFT5 is associated with the short-day-specific flowering of tobacco cultivar Maryland Mammoth

Flowering in day-neutral tobacco (Nicotiana tabacum) cultivars requires the photoperiod-dependent expression of FLOWERING LOCUS T (FT)-like floral activators, which compete with FT-like inhibitors to interact with FD proteins and induce the switch from vegetative to reproductive growth. In the short-day (SD) cultivar Maryland Mammoth (MM), vegetative growth persists under long-day (LD) conditions, generating unusually tall plants. We found that overexpression of the major LD floral inducer (NtFT5) from the day-neutral cultivar Hicks induces flowering in MM plants under LD conditions. However, a 2-bp deletion near the end of the endogenous NtFT5MM gene generates a truncated NtFT5MM protein that still interacts with FD proteins but acts as a weaker floral inducer than NtFT5. The truncation does not impair NtFT5MM protein stability but may affect its binding to NtFD1, weakening the expression of target genes. Our results provide a potential explanation for the MM gigantism phenotype first observed more than 100 years ago. A two-nucleotide deletion shortens a key floral protein, weakening its ability to activate flowering and explaining why Maryland Mammoth tobacco, central to the discovery of photoperiodism over 100 years ago, only flowers under short days.

FLC genes control flowering time to varying degrees in a Brassica napus spring cultivar

In the crop Brassica napus (oilseed rape), distinct growth types have been established that differ mainly in their vernalization requirement for flowering. The need for vernalization in Arabidopsis is controlled by the expression of the floral repressor FLOWERING LOCUS C (FLC), which also regulates cold-responsive flowering in B. napus. Notably, FLC homologs are also retained in spring oilseed rape despite its lack of vernalization requirement. To elucidate the functions of the nine BnFLC homologs in a spring type, we generated CRISPR/Cas9 knockout mutants of all homologs in the cultivar Westar. We show that the loss of BnFLC genes significantly accelerates flowering, demonstrating that BnFLC genes regulate flowering in spring types independently of vernalization. Transcriptomic analyses in leaves revealed distinct expression patterns among the BnFLC genes, with some remaining active during floral transition. Finally, no epigenetic regulation of the BnFLC homologs associated with flowering time was detected, while BnFLC.A03b carried persistent repressive marks and was constitutively silenced. Unexpectedly, additional flowering time regulators, including genes typically active in the shoot apical meristem, were expressed in leaves, with some showing altered expression and chromatin states in the mutant. These findings reveal that BnFLC genes are developmentally regulated and directly control flowering in spring oilseed rape, while also modulating the expression of other floral regulators in B. napus. CRISPR/Cas9 knockout of all nine BnFLC homologs reveals that these genes regulate flowering time developmentally in spring oilseed rape while influencing the expression and chromatin states of downstream flowering regulators.

CmELF4-LIKE 3 Interacts With CmPIF7 to Regulate Short-Day-Induced Flowering in Chrysanthemum.

The photoperiod is a key environmental factor regulating flowering in the short-day plant chrysanthemum, and the molecular mechanisms of key genes responding to short-day conditions remain incompletely elucidated. This study focused on CmELF4-LIKE 3, a chrysanthemum homolog of the core photoperiod-sensing gene EARLY FLOWERING 4 (ELF4). CmELF4-LIKE 3 displayed circadian expression patterns under both long-day (LD) and short-day (SD) conditions, peaking 8 h after dawn, with significantly higher expression under SD than LD. The gene was highly expressed in stems and leaves, and subcellular localization confirmed its nuclear localization. Genetic transformation experiments showed that overexpression of CmELF4-LIKE 3 accelerated flower bud appearance by 3-5 days compared to the wild type, whereas RNAi lines delayed bud emergence by 4-8 days, demonstrating that CmELF4-LIKE 3 promotes flowering in chrysanthemum. Yeast two-hybrid (Y2H) and tobacco luciferase complementation (LUC) assays both verified a physical interaction between CmELF4-LIKE 3 and CmPIF7, a key component of the light signaling pathway. Quantitative real-time PCR (qRT-PCR) analysis revealed significant changes in the expression of downstream flowering-related genes CmCOL5 and CmCO in CmELF4-LIKE 3 transgenic lines. Additionally, tobacco transient LUC assays demonstrated that CmPIF7 activates the CmCOL5 promoter. In summary, this study established that CmELF4-LIKE 3 interacts with CmPIF7 to cooperatively regulate short-day-induced flowering in chrysanthemum. These findings not only provide key genetic resources for precise flowering time manipulation in chrysanthemum, but also offer new insights into the crosstalk between the circadian clock and light signaling pathways in plants.

BrDDB1A promoted flowering via age pathway in Chinese cabbage

Constitutive overexpression of GRF21, a 14-3-3 family protein, delays flowering time in maize (Zea mays).

BACKGROUND Flowering time represents a pivotal agronomic trait that determines regional adaptability and grain yield in maize (Zea mays). Members of the 14-3-3 protein family, also known as general regulatory factors (GRFs), function as central modulators of diverse developmental and physiological processes in plants. However, their specific roles in regulating flowering time in maize remain undefined. RESULTS Here, we present a functional characterization of GRF21, a maize GRF family member, with particular emphasis on its role in floral transition. Through an integrative approach combining phylogenetic analysis, gene transformation, and genome-wide transcriptomic analysis, we show that constitutive overexpression of GRF21 delays flowering in maize, suggesting a potential role in flowering-time regulation. GRF21 localizes to both the nucleus and cytoplasm and accumulates predominantly in roots, stems, and reproductive tissues. Furthermore, transcriptomic analyses, supported by quantitative RT-PCR and dual-luciferase reporter assays, reveal that GRF21 represses the transcription of key flowering-promoting genes, including Zea mays CENTRORADIALIS 7 (ZCN7), ZCN8, and ZCN12, thereby suppressing floral transition. CONCLUSIONS Collectively, these findings implicate GRF21 as a negative regulator of flowering time in maize, as evidenced by the delayed flowering phenotype associated with its overexpression. This work expands the current molecular framework underlying floral initiation and highlights GRF21 as a promising target for maize breeding.

The WD40 repeat protein OsDPMS1 controls pistil development and female fertility in rice.

The pistil, a key female reproductive organ in flowering plants, plays a critical role in sexual reproduction. Although pistil function has been well studied in some species, the molecular mechanisms governing its development in rice (Oryza sativa) remain unclear. Here, we isolated and characterized a female-sterile rice mutant, Osdpms1, that exhibits pleiotropic reproductive defects, including greater stigma number and aberrant gametophyte development, while maintaining normal vegetative growth and male fertility. Using map-based cloning, genetic complementation, and CRISPR-Cas9 knockout experiments, we determined that LOC_Os07g03160 (named OsDPMS1), encoding a protein containing a WD40 repeat domain, is the causal gene underlying the mutant phenotype. OsDPMS1 was predominantly expressed during the flowering stage, and subcellular localization experiments revealed that OsDPMS1 localizes to both the nucleus and the cytoplasm. Using yeast two-hybrid, bimolecular fluorescence complementation, and GST-pulldown assays, we demonstrated that OsDPMS1 physically interacts with three components of the 26S proteasome pathway: OsUBQ, OsCDC48, and OsCDC48E. Furthermore, we showed that the female sterility of Osdpms1 can be efficiently maintained via seed production technology. When we combined Osdpms1 with male-sterile lines for hybrid seed production in a mixed planting manner, we achieved yield potentials comparable to those using conventional row-planting methods. Our findings establish OsDPMS1 as a critical regulator of pistil development and female fertility in rice and highlight its potential application in hybrid rice breeding programs.