Search Results (26)

The three-amino-acid-loop-extension (TALE) gene family encodes a group of plant-specific homeodomain transcription factors that play indispensable roles in plant growth, development, and adaptation to environmental stresses. Although TALE genes have been extensively investigated in several plant species, their genome-wide characteristics and potential functions in maize, particularly in response to phosphorus deficiency, remain poorly understood. In the present study, a comprehensive genome-wide identification and characterization of the maize TALE gene family were conducted using bioinformatics approaches, followed by an investigation of their transcriptional responses to low-phosphorus (LP) stress. A total of 40 ZmTALE genes (ZmTALE1–ZmTALE40) were identified and phylogenetically classified into four subfamilies: BEL1-like, KNOX I, KNOX II, and KNOX III. Members within the same subfamily exhibited highly conserved gene structures and motif compositions, reflecting their evolutionary conservation. Chromosomal localization and synteny analyses demonstrated that segmental duplication has been the predominant force driving the expansion of the ZmTALE gene family during maize evolution. Promoter analysis revealed that the upstream regulatory regions of ZmTALE genes were enriched in light-responsive, phytohormone-responsive, and abiotic stress-related cis-acting regulatory elements, implying their potential involvement in multiple developmental and stress-responsive pathways. Expression profiling under LP conditions revealed pronounced genotype-dependent transcriptional responses among different maize inbred lines. Notably, ZmTALE1/5/12/14/18/30/31/33/36 were significantly induced by LP stress, whereas ZmTALE10 and ZmTALE37 were markedly repressed. These differentially expressed genes represent promising candidates for further functional investigation of phosphorus-deficiency tolerance in maize. Furthermore, ZmTALE10, ZmTALE14, and ZmTALE31 are nuclear-localized transcriptional activators. Taken together, these findings provide valuable insights into the evolutionary characteristics and potential biological functions of the maize TALE gene family and offer candidate genes for developing phosphorus-efficient maize cultivars through molecular breeding. Full article

Class I KNOX1 (KNOTTED1-like homeobox 1) transcription factors integrate gibberellin (GA), cytokinin (CK), and auxin (IAA) signaling to maintain shoot apical meristem identity and coordinate plant organogenesis. This review examines the structural conservation, evolutionary dynamics, and regulatory architecture of KNOX1 genes across horticultural crops, drawing essential mechanistic context from model species. We synthesize KNOX1 functions in six agronomic domains, including plant architecture and branching, leaf morphogenesis and ornamental traits, floral development and sex determination, fruit formation and quality, storage organ specification, and abiotic stress resilience. Particular attention is given to recent breakthroughs in cucurbit inferior ovary development, tomato chloroplast patterning, and potato tuber morphogenesis. We identify critical bottlenecks constraining translation, including fragmented regulatory networks, recalcitrant transformation systems in woody perennials, uneven taxonomic coverage favoring annual vegetables over ornamentals and medicinal species, and a near-complete absence of multi-environment field validation. We propose four strategic priorities to bridge this gap: (i) construction of spatiotemporal expression atlases using single-cell and spatial transcriptomics; (ii) tissue-specific and promoter-engineered CRISPR/Cas9 editing to circumvent pleiotropic penalties; (iii) cross-species comparative evo–devo analysis of lineage-specific innovations (compound leaves, inferior ovaries, tubers); and (iv) integrated field trials assessing genotype-by-environment interactions and trait stability. This framework aims to accelerate KNOX1-directed molecular design breeding in horticultural crops. Full article

KNOTTED1-LIKE HOMEOBOX (KNOX) genes are conserved transcription factors that play crucial roles in plant growth, development, and stress responses. However, systematic characterization of the KNOX family in Malus sieversii, a valuable germplasm resource with outstanding stress tolerance and flavonoid accumulation, remains lacking. In this study, we performed a genome-wide identification of the KNOX gene family in M. sieversii and identified 21 MsiKNOX genes. Phylogenetic analysis classified these genes into three subfamilies (Class I, II, and M), with structural features and motif compositions consistent with those of their orthologs in Arabidopsis thaliana and cultivated apple. Chromosomal localization revealed an uneven distribution across 13 chromosomes, and synteny analysis indicated both conserved evolution and lineage-specific expansion of the KNOX family in M. sieversii. Promoter cis-element analysis suggested that MsiKNOX genes are potentially involved in responses to multiple abiotic stresses and hormone signaling. Expression profiling under ABA and GA treatments showed that most MsiKNOX genes responded differentially to these phytohormones. Notably, MsiKNOX09 was significantly upregulated by ABA and downregulated by GA, and was further shown to physically interact with the anthocyanin-associated MsiMYB1 in yeast two-hybrid and split-luciferase assays. These findings provide a comprehensive overview of the KNOX gene family in M. sieversii and suggest that MsiKNOX09 acts as a hormone-responsive regulator and may participate in MsiMYB1-mediated regulatory pathways. Full article

Seed physical dormancy, also known as hard-seededness, is a characteristic commonly found in higher plants, which functions to prevent water and oxygen from passing through the impermeable seed coat. Background: Notably, seed dormancy has emerged as a critical factor in the domestication of leguminous plants. Alfalfa (Medicago sativa L.) is a globally cultivated high-quality legume forage crop, while the seeds from different varieties maintain varying degrees of hard-seededness. However, the molecular mechanisms underlying physical dormancy in alfalfa seeds remain poorly understood. In particular, the regulatory mechanisms at the transcriptomic level remain unclear, which has hindered the breeding process of varieties with low hard-seededness. Methods: In this study, we performed global transcriptome analysis to discover the genes specifically expressed in the alfalfa seed coat and provide insights into alfalfa seeds’ physical dormancy domestication traits. RNA sequencing was performed on various alfalfa tissues, including roots, stems, leaves, flowers, and seed coats. Results: This analysis led to the identification of 4740 seed coat-specific expressed genes, including key genes such as KNOX4 (a class II KNOTTED-like homeobox gene), qHs1 (encoding endo-1,4-β-glucanase), GmHs1-1 (encoding a calcineurin-like metallophosphoesterase), and KCS12 (β-ketoacyl-CoA synthase). In addition, several seed coat-specific transcription factor families were identified, including ERF, B3, and NAC, among others. Furthermore, a comparison of gene expression profiles between seeds with and without physical dormancy revealed 60 upregulated and 197 downregulated genes associated with physical dormancy. Crucially, functional enrichment analysis demonstrated that these genes are predominantly associated with lipid metabolism pathways, particularly those involved in the formation of “monolayer-surrounding lipid storage bodies.” Conclusions: This key finding suggests that the establishment of physical dormancy is closely linked to the biosynthesis and deposition of specialized lipid-based layers in the seed coat, which likely constitute the primary barrier to water penetration. Our study thus provides fundamental insights and a valuable genetic resource for future functional studies aimed at deciphering and manipulating physical dormancy in alfalfa. Full article

The establishment of dorsoventral polarity is a critical step in leaf morphogenesis, enabling the transition from radial primordia to flattened laminae. The MYB domain transcription factor ASYMMETRIC LEAVES1 (AS1) plays a central role in this process by regulating leaf polarity and developmental transitions, primarily through the repression of Class I KNOX genes. Here, four AS1 paralogs were identified in soybean (Glycine max), two of which showed collinearity with Arabidopsis thaliana and Medicago truncatula. The AS1 proteins of soybean and Arabidopsis exhibit high conservation, whereas the four GmAS1 genes in soybean display different tissue-specific expression patterns. Strikingly, each GmAS1 gene was able to fully rescue the defective phenotype of the Arabidopsis as1 mutant, indicating that GmAS1 genes are functionally conserved in leaf polarity regulation. Promoter analysis further indicated that GmAS1 genes are enriched in cis-acting elements related to light response, hormone regulation, development, and stress response, suggesting potential subfunctionalization among these paralogs. In conclusion, these findings demonstrate that GmAS1 genes are evolutionarily conserved in function but potentially diversified in regulation, providing new insights into their role in leaf polarity and stress adaptation. Full article

ASYMMETRIC LEAVES1 (AS1) and AS2 play essential roles in regulating leaf development in plants. However, their functional roles in soybean remain poorly understood. Here, we identified two members of the soybean AS1 gene family, GmAS1a and GmAS1c, which exhibit high expression levels in stem and leaf tissues. Using the CRISPR/Cas9 system, we targeted four GmAS1 and three GmAS2 genes, generating mutant lines with distinct leaf development phenotypes, including wrinkling (refers to fine lines and creases on the leaf surface, like aged skin texture), curling (describes the inward or outward rolling of leaf edges, deviating from the typical flat shape), and narrow. We found that functional redundancy exists among the four GmAS1 genes in soybean. GmAS1 and GmAS2 cooperatively regulate leaf curling, leaf crinkling phenotypes, and leaf width in soybean, with functional redundancy also observed between these two genes. Transcriptome sequencing analysis of w3 mutant (as1b as1c as1d as2a as2b as2c) identified 1801 differentially expressed genes (DEGs), including 192 transcription factors (TFs). Gene ontology enrichment analysis revealed significant enrichment of DEGs in pathways associated with plant hormone biosynthesis and signal transduction. A detailed examination of the DEGs showed several genes involved in the development of leaf lateral organs, such as KNOX (SHOOT MERISTEMLESS (STM), KNAT1, KNAT2, and KNAT6), LOB (LBD25, LBD30), and ARP5, were down-regulated in w3/WT (wild-type) comparison. CRISPR/Cas9-mediated targeted mutagenesis of the GmAS1/2 genes significantly impairs leaf development and polarity establishment in soybean, providing valuable germplasm resources and a theoretical framework for future studies on leaf morphogenesis. Full article

Passion fruit (Passiflora edulis), a tropical crop of significant economic value, exhibits temperature-sensitive floral development. Here, we identified 23 TALE transcription factors (PeTALEs) and characterized their roles in floral organogenesis and thermal adaptation. Phylogenetic analysis classified PeTALEs into KNOX and BELL subfamilies, with conserved domain architectures and cis-regulatory elements linked to stress and hormone signaling. Spatiotemporal expression profiling revealed PeTALE21 as a key regulator of corona initiation, while PeTALE17 dominated in later floral stages. Temperature stress assays demonstrated cold-induced upregulation of PeTALE15/16/19/22 and heat-mediated suppression of PeTALE10/18/21. Yeast two-hybrid assays uncovered functional interactions between PeTALE3/16/18/22/23, highlighting a network governing floral thermoresilience. This study provides the first genome-wide analysis of PeTALEs, offering insights for breeding climate-resilient passion fruit varieties. Full article

Salvia miltiorrhiza is a herbaceous plant that possesses significant medicinal value. Land salinization affects the growth of S. miltiorrhiza, resulting in a decline in its quality and yield. Knotted1-like homeobox (KNOX) genes are transcription factors that play important roles in plant growth and abiotic stress. The characteristics and functions of KNOX genes in S. miltiorrhiza remain unclear. Here, we identified ten KNOX genes in S. miltiorrhiza, all of which possess the characteristic four domains: KNOX1, KNOX2, ELK, and HD. These SmKNOXs were divided into two groups together with homologous genes. Cis-acting element analysis indicated all SmKNOXs contained elements associated with phytohormone, light, and stress response. The SmKNOXs show tissue-specific expression among roots, stems, leaves, and flowers. We assessed the response of the SmKNOXs to salt stress using quantitative RT-PCR analysis. Notably, SmKNOX4 expression significantly decreased within 24 h of salt exposure, while SmKNOX1, SmKNOX2, SmKNOX3, SmKNOX8, and SmKNOX9 showed significant increases. The expression of SmKNOX1, SmKNOX2, and SmKNOX3 was significantly positively correlated with that of their target genes, GA20ox1 and S11 MYB. These findings suggest that SmKNOXs and their target genes respond to salt stress, providing a foundation for studies of SmKNOXs and the potential genetic improvement of S. miltiorrhiza. Full article

Pinellia ternata is a medicinal plant that has important pharmacological value, and the bulbils serve as the primary reproductive organ; however, the mechanisms underlying bulbil initiation remain unclear. Here, we characterized bulbil development via histological, transcriptomic, and targeted metabolomic analyses to unearth the intricate relationship between hormones, genes, and bulbil development. The results show that the bulbils initiate growth from the leaf axillary meristem (AM). In this stage, jasmonic acid (JA), abscisic acid (ABA), isopentenyl adenosine (IPA), and salicylic acid (SA) were highly enriched, while indole-3-acetic acid (IAA), zeatin, methyl jasmonate (MeJA), and 5-dexoxystrigol (5-DS) were notably decreased. Through OPLS-DA analysis, SA has emerged as the most crucial factor in initiating and positively regulating bulbil formation. Furthermore, a strong association between IPA and SA was observed during bulbil initiation. The transcriptional changes in IPT (Isopentenyltransferase), CRE1 (Cytokinin Response 1), A-ARR (Type-A Arabidopsis Response Regulator), B-ARR (Type-B Arabidopsis Response Regulator), AUX1 (Auxin Resistant 1), ARF (Auxin Response Factor), AUX/IAA (Auxin/Indole-3-acetic acid), GH3 (Gretchen Hagen 3), SAUR (Small Auxin Up RNA), GA2ox (Gibberellin 2-oxidase), GA20ox (Gibberellin 20-oxidase), AOS (Allene oxide synthase), AOC (Allene oxide cyclase), OPR (Oxophytodienoate Reductase), JMT (JA carboxy l Methyltransferase), COI1 (Coronatine Insensitive 1), JAZ (Jasmonate ZIM-domain), MYC2 (Myelocytomatosis 2), D27 (DWARF27), SMAX (Suppressor of MAX2), PAL (Phenylalanine Ammonia-Lyase), ICS (Isochorismate Synthase), NPR1 (Non-expressor of Pathogenesis-related Genes1), TGA (TGACG Sequence-specific Binding), PR-1 (Pathogenesis-related), MCSU (Molybdenium Cofactor Sulfurase), PP2C (Protein Phosphatase 2C), and SnRK (Sucrose Non-fermenting-related Protein Kinase 2) were highly correlated with hormone concentrations, indicating that bulbil initiation is coordinately controlled by multiple phytohormones. Notably, eight TFs (transcription factors) that regulate AM initiation have been identified as pivotal regulators of bulbil formation. Among these, WUS (WUSCHEL), CLV (CLAVATA), ATH1 (Arabidopsis Thaliana Homeobox Gene 1), and RAX (Regulator of Axillary meristems) have been observed to exhibit elevated expression levels. Conversely, LEAFY demonstrated contrasting expression patterns. The intricate expression profiles of these TFs are closely associated with the upregulated expression of KNOX(KNOTTED-like homeobox), suggesting a intricate regulatory network underlying the complex process of bulbil initiation. This study offers a profound understanding of the bulbil initiation process and could potentially aid in refining molecular breeding techniques specific to P. ternata. Full article

The development of both animals and plants relies on populations of pluripotent stem cells that provide the cellular raw materials for organ and tissue formation. Plant stem cell reservoirs are housed at the shoot and root tips in structures called meristems, with the shoot apical meristem (SAM) continuously producing aerial leaf, stem, and flower organs throughout the life cycle. Thus, the SAM acts as the engine of plant development and has unique structural and molecular features that allow it to balance self-renewal with differentiation and act as a constant source of new cells for organogenesis while simultaneously maintaining a stem cell reservoir for future organ formation. Studies have identified key roles for intercellular regulatory networks that establish and maintain meristem activity, including the KNOX transcription factor pathway and the CLV-WUS stem cell feedback loop. In addition, the plant hormones cytokinin and auxin act through their downstream signaling pathways in the SAM to integrate stem cell activity and organ initiation. This review discusses how the various regulatory pathways collectively orchestrate SAM function and touches on how their manipulation can alter stem cell activity to improve crop yield. Full article

The KNOX transcription factor plays crucial roles in regulating fiber growth in plants. Although the genome of ramie, an important fiber crop in China, is available, knotted related homeobox (KNOX) genes have not been systematically explored in this crop. In this study, seven members of the KNOX gene from the ramie genome were identified and assigned to two groups, Class I and II. The intron–exon structure, conserved domain architecture, cis-regulating elements, and expression pattern showed distinct differences among the seven KNOX regulators. One of the genes, Bnt07G011994, encodes an ortholog of Arabidopsis fiber-growth-related KNAT7, and is differentially expressed among barks undergoing different stages of fiber growth. The overexpression of Bnt07G011994 dramatically decreases the fiber number in transgenic Arabidopsis, indicating a negative role played by this gene in modulating fiber growth. Further transcriptome analysis of transgenic Arabidopsis revealed that the overexpression of Bnt07G011994 resulted in an expression change in 14 pectin biosynthesis-/metabolism-related genes. These findings provide a useful foundation for further investigating the function of KNOX genes in ramie, and provide an important insight into the involvement of the ramie KNOX gene in fiber growth. Full article

Class 2 KNOX homeobox transcription factors (KNOX2) play a role in promoting cell differentiation in several plant developmental processes. In Arabidopsis, they antagonize the meristematic KNOX1 function during leaf development through the modulation of phytohormones. In Medicago truncatula, three KNOX2 genes belonging to the KNAT3/4/5-like subclass (Mt KNAT3/4/5-like or MtKNOX3-like) redundantly works upstream of a cytokinin-signaling module to control the symbiotic root nodule formation. Their possible role in the response to abiotic stress is as-of-yet unknown. We produced transgenic M. truncatula lines, in which the expression of four MtKNOX3-like genes was knocked down by RNA interference. When tested for response to water withdrawal in the soil, RNAi lines displayed a lower tolerance to drought conditions compared to the control lines, measured as increased leaf water loss, accelerated leaf wilting time, and faster chlorophyll loss. Reanalysis of a transcriptomic M. truncatula drought stress experiment via cluster analysis and gene co-expression networks pointed to a possible role of MtKNOX3-like transcription factors in repressing a proline dehydrogenase gene (MtPDH), specifically at 4 days after water withdrawal. Proline measurement and gene expression analysis of transgenic RNAi plants compared to the controls confirmed the role of KNOX3-like genes in inhibiting proline degradation through the regulation of the MtPDH gene. Full article

Branching is an important agronomic and economic trait in cut chrysanthemums. The axillary meristem (AM) formation of the axillary buds of cut chrysanthemums has a decisive role in its branching characteristics. However, little is known about the regulation mechanism of axillary meristem formation in chrysanthemums at the molecular level. Members of the Homeobox gene family especially genes belonging to the class I KNOX branch play a key role in regulating the axillary bud growth and development processes of plants. In this study, three genes belonging to the class I KNOX branch, CmKNAT1, CmKNAT6, and CmSTM were cloned from chrysanthemums, and their functions in regulating axillary bud formation were examined. The subcellular localization test showed that these three KNOX genes were expressed in the nucleus, so all of them might function as transcription factors. The results of the expression profile analysis showed that these three KNOX genes were highly expressed in the AM formation stage of axillary buds. Overexpression of KNOX genes result in a wrinkled leaf phenotype in tobacco and Arabidopsis, which may be related to the excessive division of leaf cells, resulting in the proliferation of leaf tissue. Furthermore, overexpression of these three KNOX genes enhances the regeneration ability of tobacco leaves, indicating that these three KNOX genes may participate in the regulation of cell meristematic ability, thus promoting the formation of buds. In addition, the results of fluorescence quantitative testing showed that these three KNOX genes may promote the formation of chrysanthemum axillary buds by promoting the cytokinin pathway while inhibiting the auxin and gibberellin pathways. In conclusion, this study demonstrated that CmKNAT1, CmKNAT6, and CmSTM genes were involved in regulating axillary bud formation of Chrysanthemum × morifolium and preliminarily revealed the molecular mechanism of their regulation of AM formation. These findings may provide a theoretical basis and candidate gene resources for genetic engineering breeding of new varieties of cut chrysanthemums without lateral branches. Full article

Knotted1-like homeobox (KNOX) transcription factors are involved in plant development, playing complex roles in aerial organs. As Prunus species include important fruit tree crops of Italy, an exhaustive investigation of KNOX genes was performed using genomic and RNA-seq meta-analyses. Micropropagation is an essential technology for rootstock multiplication; hence, we investigated KNOX transcriptional behavior upon increasing 6-benzylaminopurine (BA) doses and the effects on GF677 propagules. Moreover, gene function in Prunus spp. was assessed by Gisela 6 rootstock transformation using fluorescence and peach KNOX transgenes. Based on ten Prunus spp., KNOX proteins fit into I-II-M classes named after Arabidopsis. Gene number, class member distribution, and chromosome positions were maintained, and exceptions supported the diversification of Prunus from Cerasus subgenera, and that of Armeniaca from the other sections within Prunus. Cytokinin (CK) cis-elements occurred in peach and almond KNOX promoters, suggesting a BA regulatory role in GF677 shoot multiplication as confirmed by KNOX expression variation dependent on dose, time, and interaction. The tripled BA concentration exacerbated stress, altered CK perception genes, and modified KNOX transcriptions, which are proposed to concur in in vitro anomalies. Finally, Gisela 6 transformation efficiency varied (2.6–0.6%) with the genetic construct, with 35S:GFP being more stable than 35S:KNOPE1 lines, which showed leaf modification typical of KNOX overexpression. Full article

Leaf shape, as one of the clearest manifestations of plant morphology, shows considerable variation owing to genetics and the environment. Leaf initiation occurs in the peripheral zone of the SAM and goes through the three overlapping phases of leaf primordium initiation, leaf dorsiventral development, and leaf marginal meristem establishment. Transcription factors, such as KNOX, WOX, and CUC; hormone-regulating genes, such as GA2ox, GA20ox, and PIN1; and miRNAs such as miR164/165 are tightly involved in leaf shaping through the generation of intricate cooperative networks in different temporal phases and specific tissue zones. Here, we briefly discuss the critical interplay occurring between certain genes and the pivotal role these play in the leaf developmental network and phytohormone regulation, including AS1/AS2–KNOX–GA20ox–GA, miR164–NAM/CUC–PIN1–auxin, and CUC–BAS1/CYP734A–BR, and we attempt to summarize several basic insights into the mechanisms of leaf shape regulation. Full article