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11 recordsLinked to original sources
PubMed2025

Balancing nutrient remobilization and photosynthesis: proteomic insights into the dual role of lupin cotyledons after germination.

Efficient nutrient mobilization from seed storage tissues is essential for seedling establishment, particularly in legumes such as Lupinus albus (white lupin), which thrive in nutrient-poor soils. This study investigates the role of cotyledons in nitrogen (N) and mineral remobilization after germination during their transition from storage organs to photosynthetically active tissues, including the metabolic challenges posed by the coexistence of these two functions in epigeal germination. We cultivated white lupin seedlings under nitrogen-deficient conditions, analyzing cotyledon composition and function over 28 days. Our results indicate that 60% of cotyledon-stored proteins are degraded within the first 8 days, with free amino acids transiently accumulating before being redistributed to support growth. The progressive depletion of cotyledon reserves was accompanied by structural and metabolic changes, including an increase in photosynthetic proteins. However, cotyledon photosynthetic capacity remained lower than that of true leaves, suggesting a transient role in energy metabolism. The loss of cotyledons before day 12 significantly impaired seedling development, emphasizing their critical contribution to nitrogen, phosphate, and micronutrient supply during early growth. Comparative proteomic analysis revealed dynamic shifts in nutrient transport, amino acid metabolism, and stress response pathways following cotyledon removal. These findings underscore the significance of cotyledon nutrient remobilization in legume adaptation to low-fertility soils and highlight potential targets for breeding strategies aimed at improving nutrient use efficiency. By optimizing cotyledon nutrient composition and function, future breeding efforts could enhance seedling vigor, reduce fertilizer dependency, and improve the nutritional value of lupin-based foods.

Lupinus↗
PubMed2025

A PIF-regulated switch in cell axis growth drives cotyledon expansion through tissue-specific cell expansion and division.

Despite its crucial role during seedling deetiolation, cotyledon expansion has been largely overlooked, with hypocotyl elongation favored as the primary phenotypic readout in light signaling research. Here, we investigate how cotyledon expansion is regulated during seedling establishment and reveal that light-induced cotyledon expansion involves a rapid switch in growth direction - from longitudinal in darkness to transversal upon initial light exposure. Using PIFq- and phyA/phyB-deficient Arabidopsis mutants, we demonstrate that this switch is repressed by PIFs in the dark and promoted by phytochromes under red light. Notably, expansion is antagonistically regulated in the light by GUN1-mediated plastid retrograde signaling. Cotyledon expansion involves rapid epidermis cell expansion, transitioning from rectangular in darkness to characteristic lobed cells in light. Importantly, our findings show that mesophyll extension is driven not only by cell enlargement but also by palisade cell division, consistent with an enrichment of cell cycle-related genes that are antagonistically regulated by the PIF/phy system and retrograde signaling in the cotyledon. Finally, using mutant lines expressing PIF1 and phyB specifically in the epidermis, we establish that epidermal expansion can drive palisade cell growth, while mesophyll cell division is predominantly regulated by light at the tissue-specific level. This study provides a novel framework for investigating cotyledon expansion during seedling deetiolation, incorporating tissue-level regulation. We propose that cotyledons serve as an excellent model for studying morphogenesis and organ geometry, which in plants is governed by directional cell growth.

Cotyledon↗
PubMed2025

Nitrate modulates pectin metabolism and cell wall mechanics during cell expansion in Arabidopsis.

Nitrate is a key nutrient and one of the most important nitrogen sources for land plants. Besides its nutritional role, nitrate is a signal molecule that regulates plant gene expression, metabolism, physiology, growth, and development. In cotyledons and true leaves, nitrate promotes growth by inducing cell expansion. Plant cell expansion requires changes in the cell wall. However, there is scant information on the influence of nitrate on cell wall metabolism and properties during cell expansion and growth. Here, we demonstrate that nitrate availability modulates pectin metabolism, a major polysaccharide of the primary cell wall. Using colorimetric assays, immunohistochemistry, and confocal microscopy, we show that nitrate enhances methylesterified pectin during cotyledon cell expansion. This is achieved by increasing galacturonic acid (GalA) deposition as homogalacturonan (HG) and by decreasing global PME activity. We further show that this regulation is dependent on nitrate signaling pathway components, including NRT1.1 and NLP7. Pectin methylesterification state impacts the mechanical properties of the cell wall. We characterized cell wall elasticity changes during nitrate-induced expansion using atomic force microscopy (AFM) and automatic confocal microextensometry (ACME). We found that nitrate induces cell wall softening at both cellular and whole-tissue levels during this expansion process. Our results indicate pectin metabolism plays an important role in nitrate-induced cell expansion and cotyledon growth in Arabidopsis. We provide insights into the interplay between nitrate signaling, cell wall metabolism, and biomechanical properties for cell expansion. Our results contribute to our understanding of how plants sense and respond to environmental cues for growth.

Pectins↗
PubMed2026

Targeted expression of Glycine max isoflavone synthase enhances daidzein and genistein content in soybean.

Isoflavonoids are key secondary metabolites in leguminous plants that play essential roles in plant physiology and provide significant health benefits to humans. In the isoflavone biosynthetic pathway, isoflavone synthase (IFS) catalyzes the conversion of naringenin and liquiritigenin into the bioactive isoflavones genistein and daidzein. This study aimed to enhance genistein and daidzein accumulation in soybean seeds through genetic engineering. Agrobacterium tumefaciens strain EHA105 harboring the binary vector pCAMBIA1301 containing GmIFS under the control of a seed-specific promoter (Gmβ-conglycinin) was used to transform modified half-seed explants of soybean cv. JS335. Hygromycin-B-resistant plants were regenerated, hardened, and confirmed by histochemical GUS assay. Molecular analysis by PCR validated the presence of the GmIFS transgene, yielding a 700 bp amplicon. Biochemical analysis revealed that seeds of T₀ transgenic plants showed a 1.53-fold increase in total phenolic content and a 3.67-fold increase in flavonoid content compared to non-transformed controls. Antioxidant assays demonstrated significantly higher DPPH radical-scavenging activity and ferric-reducing antioxidant power (FRAP) in GmIFS-overexpressing plants. HPLC analysis further indicated that transgenic seeds accumulated, on average, 4.07-fold higher daidzein and 1.75-fold higher genistein levels relative to control plants. qRT-PCR analysis showed significantly elevated GmIFS expression in immature cotyledons, mature cotyledons, and seeds of transgenic plants. Overall, these results demonstrate that GmIFS overexpression effectively enhances isoflavone production in soybean seeds, highlighting the potential of metabolic engineering of biosynthetic pathway genes to improve nutritional quality.

Glycine max↗
PubMed2026

The Spatiotemporal Genetic Architecture of Seed Vigor in Upland Cotton.

Seed vigor underpins uniform crop establishment, but its dynamic genetics are understudied. Combining high-resolution temporal phenotyping and genomics in upland cotton, we used the SeedRanger platform to record 17 image-based traits every 30 min over 120 h, revealing stage-specific heritability and identifying 541 seed-vigor loci. These loci show extensive pleiotropy and temporal coordination, forming a genetic network that preserves developmental continuity; 8.9% overlap regions under domestication selection, indicating concurrent optimization with fiber yield. Functional validation of FLA2, a candidate gene underlying a dynamic QTL, implicates auxin-mediated control of radicle elongation and cotyledon development. This temporal framework exposes dynamic genetic architecture and breeding targets for high-vigor crops.

Gossypium↗
PubMed2025

Using Callus as an Ex Vivo System for Chromatin Analysis.

Next-generation sequencing has revolutionized epigenetics research, enabling a comprehensive analysis of DNA methylation and histone modification profiles to explore complex biological systems at unprecedented depth. Deciphering the intricate epigenetic mechanisms that regulate gene activity presents significant challenges, including the issue of analyzing heterogeneous cell populations in bulk. Bulk analysis introduces bias and can obscure crucial information by averaging readouts from distinct cells. Various approaches have been developed to address this issue, such as cell-type-specific enrichment or single-cell sequencing techniques. However, the need for transgenic lines with fluorescent markers, along with technical challenges such as efficient protoplast isolation and low yield, limits their widespread adoption and use in multi-omic studies. This review discusses the pros and cons of these approaches, providing a valuable basis for selecting the most suitable strategy to minimize heterogeneity. We will also highlight the use of cotyledon-derived callus as an ex vivo system as a simple, accessible, and robust platform for enabling high-throughput multi-omic analyses.

Chromatin↗
PubMed2025

Companion cells with high florigen production express other small proteins and reveal a nitrogen-sensitive FT repressor.

The precise onset of flowering is crucial to ensure successful plant reproduction. The gene FLOWERING LOCUS T (FT) encodes florigen, a mobile signal produced in leaves that initiates flowering at the shoot apical meristem. In response to seasonal changes, FT is induced in phloem companion cells located in distal leaf regions. Thus far, a detailed molecular characterization of the FT-expressing cells has been lacking. Here, we used bulk nuclei RNA-seq and single nuclei RNA (snRNA)-seq to investigate gene expression in FT-expressing cells and other phloem companion cells. Our bulk nuclei RNA-seq demonstrated that FT-expressing cells in cotyledons and true leaves showed differences especially in FT repressor genes. Within the true leaves, our snRNA-seq analysis revealed that companion cells with high FT expression form a unique cluster in which many genes involved in ATP biosynthesis are highly upregulated. The cluster also expresses other genes encoding small proteins, including the flowering and stem growth inducer FPF1-LIKE PROTEIN 1 (FLP1) and the anti-florigen BROTHER OF FT AND TFL1 (BFT). In addition, we found that the promoters of FT and the genes co-expressed with FT in the cluster were enriched for the consensus binding motifs of NITRATE-INDUCIBLE GARP-TYPE TRANSCRIPTIONAL REPRESSOR 1 (NIGT1). Overexpression of the paralogous NIGT1.2 and NIGT1.4 repressed FT expression and significantly delayed flowering under nitrogen-rich conditions, consistent with NIGT1s acting as nitrogen-dependent FT repressors. Taken together, our results demonstrate that major FT-expressing cells show a distinct expression profile that suggests that these cells may produce multiple systemic signals to regulate plant growth and development.

BROTHER OF FT AND TFL1↗
PubMed2025

Alternative splice acceptor site in MSH4 gene is responsible for male sterility conferred by ms5 in soybean.

In soybean breeding, using the recessive male-sterile ms5 gene, derived from fast neutron mutagenesis, for recurrent selection is advantageous because of the d2 locus, which controls cotyledon color in mature seeds and can be used as a phenotypic selection marker for ms5 male sterility. However, occasional self-fertilization occurs because of the elimination of d2 linkage and instability of male sterility. Elucidating the mechanism and the gene responsible for ms5 male sterility may resolve these problems. Using fine mapping with 15 simple sequence repeat (SSR) markers, we narrowed down the candidate ms5 locus to a 54-kbp region. Bulked-DNA analysis using next-generation sequencing revealed a deletion as a candidate variation in the region. This 15-bp deletion and a nucleotide substitution were identified in intron 1 of MutS homolog (GmMSH4), which modulates chromosomal recombination in meiosis. The ms5 transcript contained a novel exon with a premature termination codon. This exon originated from an alternative splice acceptor site caused by the deletion and nucleotide substitution, disrupting gene function. Co-segregation of male sterility with five independent mutations in GmMSH4 was confirmed using progeny of mutant lines. Mutations in GmMSH4 led to biased DNA partitioning during meiosis, resulting in collapsed or enlarged pollen and suggesting that ms5 male sterility is caused by the failure of pollen formation during meiosis due to the loss of function of GmMSH4. These findings could help explain the mechanism of instability of ms5 male sterility and improve the efficiency of recurrent selection using DNA markers in soybean breeding.

Glycine max↗
PubMed2025

Water shortage reduces PHYTOCHROME INTERACTING FACTOR 4, 5 and 3 expression and shade avoidance in Arabidopsis.

In agricultural crops, forests and grasslands, water deficit often occurs in the presence of cues from neighbouring vegetation. However, most studies have addressed separately the mechanisms of plant growth responses to these two aspects of the environment. Here we show that transferring Arabidopsis thaliana seedlings to agar containing polyethylene glycol (PEG) to restrict water availability reduces hypocotyl growth responses to shade without simultaneously affecting cotyledon expansion or its response to shade. Hypocotyl growth showed significant triple interaction among water availability, shade and the presence of PHYTOCHROME INTERACTING FACTOR 4 (PIF4), PIF5 and PIF3. Water restriction diminished auxin signalling and the activity of the PIF4, PIF5, PIF3 gene promoters and their transcript levels. The responses of PIF4 expression and hypocotyl growth to PEG were reduced in mutants of its positive morning regulators CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY). The CCA1 and LHY gene promoters also reduced their activity in response to PEG. In addition to the changes in PIF4 levels, post-transcriptional processes also contributed to the PIF4 protein response to PEG. Collectively, these results unveil PIFs as a hub that interlinks shade and drought information to control growth.

Arabidopsis↗
PubMed2026

Expansion and Nitrate-Responsive Expression of NRT3 Transport Regulators in Maritime Pine.

Nitrate uptake in plants is mediated by coordinated transporter systems, which include NPF, NRT2 and NRT3 proteins. While these families have been extensively studied in angiosperms, their evolution and regulation in conifers are still not well understood. In this work, we examined the NRT3 family in maritime pine (Pinus pinaster) and in representative plant lineages. Phylogenetic analyses of nucleotide sequences and the NRT3 protein revealed a broad expansion in gymnosperms, particularly in conifers, while copy number increases among angiosperms appeared to be more lineage-specific. In addition, we evaluated the expression of nitrate transporter genes in cotyledons, hypocotyls and roots of P. pinaster seedlings exposed to low and high concentrations of nitrate. Several NRT3 genes, particularly PpNRT3.1, PpNRT3.3 and PpNRT3.5, were significantly induced by nitrate, while most NPF and NRT2 genes showed weaker or non-significant transcriptional responses. Correlation analysis revealed distinct expression associations among the NRT3, NRT2 and NPF transporters, including a specific association between PpNRT3.4 and PpNRT2.1, as well as broader correlations among other NRT3 paralogs and NPF genes. These results indicate that the expansion of NRT3 in conifers was accompanied by transcriptional divergence among paralogs and identify potential regulatory relationships for future functional studies.

NPF↗
PubMed2025

NAM and CUC3 boundary genes maintain shoot apical meristem viability and suppress the development of axillary shoot in rice seedlings.

Cell division and differentiation within the shoot apical meristem (SAM) are essential for the morphogenesis of aboveground plant organs. This study reveals that the boundary genes OsNAM and OsCUC3 collaboratively maintain SAM activity. Loss of function in both OsNAM and OsCUC3 during the fourth leaf stage reduced SAM size, with the osnam oscuc3 mutant exhibiting abnormal leaf number and morphology. Furthermore, OsNAM and OsCUC3 inhibited the growth of axillary shoots. In the osnam oscuc3 mutant, the number of new leaves decreased, while buds in the coleoptile and the axil of the first leaf developed into tillers. Since OsNAM and OsCUC3 are involved in regulating both SAM activity and the growth of lateral shoots, we examined their expression patterns at the base of the main shoot. β-Glucuronidase (GUS) reporter activity and GFP reporter lines demonstrated that OsNAM and OsCUC3 have distinct expression patterns. Specifically, OsNAM was expressed throughout the SAM, whereas OsCUC3 was expressed only at the base of the SAM, with its expression gradually decreasing as seedlings develop. RNA sequencing analysis showed that the expression of genes related to leaf epidermal cell development, cell wall components, and hormonal signal transduction was altered in response to the loss of function of OsNAM and OsCUC3. Therefore, the boundary genes OsNAM and OsCUC3 not only inhibit the growth of axillary shoots but also regulate the development of aboveground organs, including leaf morphology and number, by maintaining the SAM activity in the main shoot.

Meristem↗