RESUMEN
The afila (af) mutation causes the replacement of leaflets by a branched mass of tendrils in the compound leaves of pea - Pisum sativum L. This mutation was first described in 1953, and several reports of spontaneous af mutations and induced mutants with a similar phenotype exist. Despite widespread introgression into breeding material, the nature of af and the origin of the alleles used remain unknown. Here, we combine comparative genomics with reverse genetic approaches to elucidate the genetic determinants of af. We also investigate haplotype diversity using a set of AfAf and afaf cultivars and breeding lines and molecular markers linked to seven consecutive genes. Our results show that deletion of two tandemly arranged genes encoding Q-type Cys(2)His(2) zinc finger transcription factors, PsPALM1a and PsPALM1b, is responsible for the af phenotype in pea. Eight haplotypes were identified in the af-harbouring genomic region on chromosome 2. These haplotypes differ in the size of the deletion, covering more or less genes. Diversity at the af locus is valuable for crop improvement and sheds light on the history of pea breeding for improved standing ability. The results will be used to understand the function of PsPALM1a/b and to transfer the knowledge for innovation in related crops.
Asunto(s)
Haplotipos , Fenotipo , Pisum sativum , Fitomejoramiento , Pisum sativum/genética , Haplotipos/genética , Genes de Plantas , Proteínas de Plantas/genética , Mutación/genética , Hojas de la Planta/genética , Cruzamiento , Factores de Transcripción/genética , Variación GenéticaRESUMEN
The first TALE homeodomain transcription factor gene to be described in plants was maize knotted1 (kn1). Dominant mutations in kn1 disrupt leaf development, with abnormal knots of tissue forming in the leaf blade. kn1 was found to be expressed in the shoot meristem but not in a peripheral region that gives rise to leaves. Furthermore, KN1 and closely related proteins were excluded from initiating and developing leaves. These findings were a prelude to a large body of work wherein TALE homeodomain proteins have been identified as vital regulators of meristem homeostasis and organ development in plants. KN1 homologues are widely represented across land plant taxa. Thus, studying the regulation and mechanistic action of this gene class has allowed investigations into the evolution of diverse plant morphologies. This review will focus on the function of TALE homeodomain transcription factors in leaf development in eudicots. Here, we discuss how TALE homeodomain proteins contribute to a spectrum of leaf forms, from the simple leaves of Arabidopsis thaliana to the compound leaves of Cardamine hirsuta and species beyond the Brassicaceae.
Asunto(s)
Proteínas de Homeodominio , Hojas de la Planta , Proteínas de Plantas , Factores de Transcripción , Hojas de la Planta/metabolismo , Hojas de la Planta/crecimiento & desarrollo , Hojas de la Planta/genética , Proteínas de Homeodominio/metabolismo , Proteínas de Homeodominio/genética , Factores de Transcripción/metabolismo , Factores de Transcripción/genética , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Regulación de la Expresión Génica de las Plantas , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/crecimiento & desarrollo , Meristema/genética , Meristema/crecimiento & desarrollo , Meristema/metabolismoRESUMEN
Here we investigate mechanisms underlying the diversification of biological forms using crucifer leaf shape as an example. We show that evolution of an enhancer element in the homeobox gene REDUCED COMPLEXITY (RCO) altered leaf shape by changing gene expression from the distal leaf blade to its base. A single amino acid substitution evolved together with this regulatory change, which reduced RCO protein stability, preventing pleiotropic effects caused by its altered gene expression. We detected hallmarks of positive selection in these evolved regulatory and coding sequence variants and showed that modulating RCO activity can improve plant physiological performance. Therefore, interplay between enhancer and coding sequence evolution created a potentially adaptive path for morphological evolution.
Asunto(s)
Arabidopsis/fisiología , Cardamine/anatomía & histología , Cardamine/genética , Evolución Molecular , Hojas de la Planta/anatomía & histología , Hojas de la Planta/genética , Arabidopsis/anatomía & histología , Arabidopsis/genética , Cardamine/clasificación , Elementos de Facilitación Genéticos/genética , Perfilación de la Expresión Génica , Genes de Plantas/genéticaRESUMEN
The complexity of compound leaves results primarily from the leaflet initiation and arrangement during leaf development. However, the molecular mechanism underlying compound leaf development remains a central research question. SlTCP24 and SlTCP29, two plant-specific transcription factors with the conserved TCP motif, are shown here to synergistically regulate compound leaf development in tomato. When both of them were knocked out simultaneously, the number of leaflets significantly increased, and the shape of the leaves became more complex. SlTCP24 and SlTCP29 could form both homodimers and heterodimers, and such dimerization was impeded by the leaf polarity regulator SlAS2, which interacted with SlTCP24 and SlTCP29. SlTCP24 and SlTCP29 could bind to the TCP-binding cis-element of the SlCKX2 promoter and activate its transcription. Transgenic plants with SlTCP24 and SlTCP29 double-gene knockout had a lowered transcript level of SlCKX2 and an elevated level of cytokinin. This work led to the identification of two key regulators of tomato compound leaf development and their targeted genes involved in cytokinin metabolic pathway. A model of regulation of compound leaf development was proposed based on observations of this study.
RESUMEN
Two interrelated problems in biology are understanding the regulatory logic and predictability of morphological evolution. Here, we studied these problems by comparing Arabidopsis thaliana, which has simple leaves, and its relative, Cardamine hirsuta, which has dissected leaves comprising leaflets. By transferring genes between the two species, we provide evidence for an inverse relationship between the pleiotropy of SHOOTMERISTEMLESS (STM) and BREVIPEDICELLUS (BP) homeobox genes and their ability to modify leaf form. We further show that cis-regulatory divergence of BP results in two alternative configurations of the genetic networks controlling leaf development. In C. hirsuta, ChBP is repressed by the microRNA164A (MIR164A)/ChCUP-SHAPED COTYLEDON (ChCUC) module and ChASYMMETRIC LEAVES1 (ChAS1), thus creating cross-talk between MIR164A/CUC and AS1 that does not occur in A. thaliana. These different genetic architectures lead to divergent interactions of network components and growth regulation in each species. We suggest that certain regulatory genes with low pleiotropy are predisposed to readily integrate into or disengage from conserved genetic networks influencing organ geometry, thus rapidly altering their properties and contributing to morphological divergence.
Asunto(s)
Arabidopsis/crecimiento & desarrollo , Arabidopsis/genética , Cardamine/crecimiento & desarrollo , Cardamine/genética , Redes Reguladoras de Genes/genética , Proteínas de Homeodominio/genética , Hojas de la Planta , Proteínas de Plantas/genética , Arabidopsis/anatomía & histología , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Cardamine/anatomía & histología , Regulación de la Expresión Génica de las Plantas , Proteínas de Homeodominio/metabolismo , MicroARNs/genética , MicroARNs/metabolismo , Hojas de la Planta/anatomía & histología , Hojas de la Planta/genética , Hojas de la Planta/crecimiento & desarrollo , Proteínas de Plantas/metabolismoRESUMEN
Compound leaf development requires the coordination of genetic factors, hormones, and other signals. In this study, we explored the functions of Class â ¡ KNOTTED-like homeobox (KNOXII) genes in the model leguminous plant Medicago truncatula. Phenotypic and genetic analyses suggest that MtKNOX4, 5 are able to repress leaflet formation, while MtKNOX3, 9, 10 are not involved in this developmental process. Further investigations have shown that MtKNOX4 represses the CK signal transduction, which is downstream of MtKNOXâ -mediated CK biosynthesis. Additionally, two boundary genes, FUSED COMPOUND LEAF1 (orthologue of Arabidopsis Class M KNOX) and NO APICAL MERISTEM (orthologue of Arabidopsis CUP-SHAPED COTYLEDON), are necessary for MtKNOX4-mediated compound leaf formation. These findings suggest, that among the members of MtKNOXâ ¡, MtKNOX4 plays a crucial role in integrating the CK pathway and boundary regulators, providing new insights into the roles of MtKNOXâ ¡ in regulating the elaboration of compound leaves in M. truncatula.
Asunto(s)
Arabidopsis , Medicago truncatula , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Hojas de la Planta/metabolismo , Meristema/metabolismo , Regulación de la Expresión Génica de las Plantas , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/metabolismoRESUMEN
Stipule morphology is a classical botanical key character used in plant identification. Stipules are considerably diverse in size, function and architecture, such as leaf-like stipules, spines or tendrils. However, the molecular mechanism that regulates stipule identity remains largely unknown. We isolated mutants with abnormal stipules. The mutated gene encodes the NODULE ROOT1 (MtNOOT1), which is the ortholog of BLADE-ON-PETIOLE (BOP) in Medicago truncatula. We also obtained mutants of MtNOOT2, the homolog of MtNOOT1, but they do not show obvious defects in stipules. The mtnoot1 mtnoot2 double mutant shows a higher proportion of transformation from stipules to leaflet-like stipules than the single mutants, suggesting that they redundantly determine stipule identity. Further investigations show that MtNOOTs control stipule initiation together with SINGLE LEAFLET1 (SGL1), which functions in development of lateral leaflets. Increasing SGL1 activity in mtnoot1 mtnoot2 is sufficient for the transformation of stipules to leaves. Moreover, MtNOOTs inhibit SGL1 expression during stipule development, which is probably conserved in legume species. Our study proposes a genetic regulatory model for stipule development, specifically with regard to the MtNOOTs-SGL1 module, which functions in two phases of stipule development, first in the control of stipule initiation and second in stipule patterning.
Asunto(s)
Arabidopsis , Medicago truncatula , Regulación de la Expresión Génica de las Plantas , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Medicago truncatula/metabolismo , Pisum sativum/genética , Hojas de la Planta/metabolismo , Mutación/genéticaRESUMEN
Compound leaves are composed of multiple separate blade units termed leaflets. In tomato (Solanum lycopersicum) compound leaves, auxin promotes both leaflet initiation and blade expansion. However, it is unclear how these two developmental processes interact. With highly variable complexity, tomato compound leaves provide an ideal system to address this question. In this study, we obtained and analyzed mutants of the WUSCHEL-RELATED HOMEOBOX (WOX) family gene SlLAM1 from tomato, whose orthologs in tobacco (Nicotiana sylvestris) and other species are indispensable for blade expansion. We show that SlLAM1 is expressed in the middle and marginal domains of leaves, and is required for blade expansion in leaflets. We demonstrate that sllam1 mutants cause a delay of leaflet initiation and slightly alter the arrangement of first-order leaflets, whereas the overall leaflet number is comparable to that of wild-type leaves. Analysis of the genetic interactions between SlLAM1 and key auxin signaling components revealed an epistatic effect of SlLAM1 in determining the final leaf form. Finally, we show that SlLAM1 is also required for floral organ growth and affects the fertility of gametophytes. Our data suggest that SlLAM1 promotes blade expansion in multiple leaf types, and leaflet initiation can be largely uncoupled from blade expansion during compound leaf morphogenesis.
Asunto(s)
Ácidos Indolacéticos/metabolismo , Reguladores del Crecimiento de las Plantas/metabolismo , Proteínas de Plantas/metabolismo , Transducción de Señal , Solanum lycopersicum/genética , Genes Homeobox , Solanum lycopersicum/crecimiento & desarrollo , Mutación , Filogenia , Hojas de la Planta/genética , Hojas de la Planta/crecimiento & desarrollo , Proteínas de Plantas/genética , Factores de Transcripción/genética , Factores de Transcripción/metabolismoRESUMEN
In most legumes, two typical features found in leaves are diverse compound forms and the pulvinus-driven nyctinastic movement. Many genes have been identified for leaf-shape determination, but the underlying nature of leaf movement as well as its association with the compound form remains largely unknown. Using forward-genetic screening and whole-genome resequencing, we found that two allelic mutants of Medicago truncatula with unclosed leaflets at night were impaired in MtDWARF4A (MtDWF4A), a gene encoding a cytochrome P450 protein orthologous to Arabidopsis DWARF4. The mtdwf4a mutant also had a mild brassinosteroid (BR)-deficient phenotype bearing pulvini without significant deficiency in organ identity. Both mtdwf4a and dwf4 could be fully rescued by MtDWF4A, and mtdwf4a could close their leaflets at night after the application of exogenous 24-epi-BL. Surgical experiments and genetic analysis of double mutants revealed that the failure to exhibit leaf movement in mtdwf4a is a consequence of the physical obstruction of the overlapping leaflet laminae, suggesting a proper geometry of leaflets is important for their movement in M. truncatula. These observations provide a novel insight into the nyctinastic movement of compound leaves, shedding light on the importance of open space for organ movements in plants.
Asunto(s)
Medicago truncatula , Pulvino , Regulación de la Expresión Génica de las Plantas , Genes de Plantas , Medicago truncatula/genética , Medicago truncatula/metabolismo , Hojas de la Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Pulvino/metabolismoRESUMEN
Leaves are derived from the shoot apical meristem with three distinct axes: dorsoventral, proximodistal and mediolateral. Different regulators are involved in the establishment of leaf polarity. Members of the class III homeodomain-leucine zipper (HD-ZIPIII) gene family are critical players in the determination of leaf adaxial identity mediated by microRNA165/166. However, their roles in compound leaf development are still unclear. By screening of a retrotransposon-tagged mutant population of the model legume plant Medicago truncatula, a mutant line with altered leaflet numbers was isolated and characterized. Mutant leaves partially lost their adaxial identity. Leaflet numbers in the mutant were increased along the proximodistal axis, showing pinnate pentafoliate leaves in most cases, in contrast to the trifoliate leaves of the wild type. Detailed characterization revealed that a lesion in a HD-ZIPIII gene, REVOLUTA (MtREV1), resulted in the defects of the mutant. Overexpression of MtMIR166-insensitive MtREV1 led to adaxialized leaves and ectopic leaflets along the dorsoventral axis. Accompanying the abnormal leaf patterning, the free auxin content was affected. Our results demonstrate that MtREV1 plays a key role in determination of leaf adaxial-abaxial polarity and compound leaf patterning, which is associated with proper auxin homeostasis.
Asunto(s)
Tipificación del Cuerpo/genética , Ácidos Indolacéticos/metabolismo , Medicago truncatula/genética , MicroARNs/genética , Reguladores del Crecimiento de las Plantas/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/metabolismo , Homeostasis , Leucina Zippers , Medicago truncatula/citología , Medicago truncatula/fisiología , Filogenia , Hojas de la Planta/citología , Hojas de la Planta/genética , Hojas de la Planta/fisiología , Proteínas de Plantas/genética , ARN de Planta/genéticaRESUMEN
In species with compound leaves, the positions of leaflet primordium initiation are associated with local peaks of auxin accumulation. However, the role of auxin during the late developmental stages and outgrowth of compound leaves remains largely unknown. Using genome resequencing approaches, we identified insertion sites at four alleles of the LATERAL LEAFLET SUPPRESSION1 (LLS1) gene, encoding the auxin biosynthetic enzyme YUCCA1 in Medicago truncatula. Linkage analysis and complementation tests showed that the lls1 mutant phenotypes were caused by the Tnt1 insertions that disrupted the LLS1 gene. The transcripts of LLS1 can be detected in primordia at early stages of leaf initiation and later in the basal regions of leaflets, and finally in vein tissues at late leaf developmental stages. Vein numbers and auxin content are reduced in the lls1-1 mutant. Analysis of the lls1 sgl1 and lls1 palm1 double mutants revealed that SGL1 is epistatic to LLS1, and LLS1 works with PALM1 in an independent pathway to regulate the growth of lateral leaflets. Our work demonstrates that the YUCCA1/YUCCA4 subgroup plays very important roles in the outgrowth of lateral leaflets during compound leaf development of M. truncatula, in addition to leaf venation.
Asunto(s)
Medicago truncatula , Regulación de la Expresión Génica de las Plantas , Prueba de Complementación Genética , Ácidos Indolacéticos , Medicago truncatula/genética , Medicago truncatula/metabolismo , Hojas de la Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMEN
miR160 adjusts auxin-mediated development by post-transcriptional regulation of the auxin response factors ARF10/16/17. In tomato, knockdown of miR160 (sly-miR160) suggested that it is required for auxin-driven leaf blade outgrowth, but whether additional developmental events are adjusted by sly-miR160 is not clear. Here, the SlMIR160 genes and the genes of its SlARFs targets were edited by CRISPR/Cas9 resulting in the isolation of loss-of-function mutants. In addition, hypomorphic mutants that accumulate variable reduced levels of sly-miR160a were isolated. We found that the loss-of-function mutants in SlMIR160a (CR-slmir160a-6/7) produced only four wiry leaves, whereas the hypomorphic mutants developed leaves and flowers with graded developmental abnormalities. Phenotypic severity correlated with the upregulation of SlARF10A. Consistent with that, double mutants in SlMIR160a and SlARF10A restored leaf and flower development indicating that over-accumulation of SlARF10A underlay the developmental abnormalities exhibited in the CR-slmir160a mutants. Phenotype severity also correlated with the upregulation of the SHOOT MERISTEMLESS homolog Tomato Knotted 2, which in turn activated the transcription of the cytokinin biosynthesis genes SlIPT2 and SlIPT4. However, no change in Tomato Knotted 2 was detected in the absence of SlARF10A, suggesting that it is upregulated due to auxin signaling suppression by SlARF10A. Knockout of sly-miR160a-targeted SlARFs showed that whereas SlARF10A is indispensable for leaf blade outgrowth and floral organ patterning, the functions of SlARF16A and SlARF17 are redundant. Taken together our results suggest that sly-miR160a promotes blade outgrowth as well as leaf and leaflet initiation and floral organ development through the quantitative regulation of its major target SlARF10A.
Asunto(s)
Flores/genética , Flores/metabolismo , Ácidos Indolacéticos/metabolismo , MicroARNs/genética , Hojas de la Planta/genética , Hojas de la Planta/metabolismo , Solanum lycopersicum/genética , Solanum lycopersicum/metabolismo , Proteínas de Arabidopsis , Sistemas CRISPR-Cas , Citocininas/genética , Citocininas/metabolismo , Flores/crecimiento & desarrollo , Regulación del Desarrollo de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Técnicas de Silenciamiento del Gen , Solanum lycopersicum/crecimiento & desarrollo , MicroARNs/fisiología , Mutación , Fenotipo , Hojas de la Planta/crecimiento & desarrollo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Transcriptoma , Regulación hacia ArribaRESUMEN
MAIN CONCLUSION: The results provide a significant verification of functional redundancy and diversity of CUC/NAM genes in legumes. The CUP-SHAPED COTYLEDON/NO APICAL MERISTEM (CUC/NAM) orthologs play key roles for plant organ boundary formation and organ development. Here, we performed a forward screen of the gamma irradiation mutagenesis population in mungbean and characterised a mutant, reduced rachis and fused leaflets (rrf1), which gave rise to the formation of compound leaves with reduced rachis and fused leaflets. Map-based cloning revealed that RRF1 encoded a CUC/NAM protein in mungbean. Phylogenetic analysis indicated that legume CUC1/CUC2 genes were classified as belonging to two subclades, and there are different copies of CUC1/CUC2 genes in legumes. Transcriptomic analysis showed that expression levels of a set of developmental regulators, including class I KNOTTED-LIKE HOMEOBOXI (KNOXI) gene and LATERAL ORGAN BOUNDARIES DOMAIN (LBD) gene, were altered in rrf1 mutants compared to the wild-type plants. Furthermore, rrf1 genetically interacted with heptafoliate leaflets1 (hel1), a mutant displaying a seven-leaflet compound leaf, to regulate leaf development in mungbean. Our results suggest functional redundancy and diversity of two subclades of CUC1/CUC2 genes in legumes, following the duplication of an ancestral gene.
Asunto(s)
Genes de Plantas/fisiología , Hojas de la Planta/crecimiento & desarrollo , Proteínas de Plantas/fisiología , Vigna/crecimiento & desarrollo , Clonación Molecular , Perfilación de la Expresión Génica , Regulación del Desarrollo de la Expresión Génica/genética , Regulación de la Expresión Génica de las Plantas/genética , Genes de Plantas/genética , Filogenia , Hojas de la Planta/genética , Proteínas de Plantas/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Vigna/genéticaRESUMEN
A key problem in biology is whether the same processes underlie morphological variation between and within species. Here, by using plant leaves as an example, we show that the causes of diversity at these two evolutionary scales can be divergent. Some species like the model plant Arabidopsis thaliana have simple leaves, whereas others like the A. thaliana relative Cardamine hirsuta bear complex leaves comprising leaflets. Previous work has shown that these interspecific differences result mostly from variation in local tissue growth and patterning. Now, by cloning and characterizing a quantitative trait locus (QTL) for C. hirsuta leaf shape, we find that a different process, age-dependent progression of leaf form, underlies variation in this trait within species. This QTL effect is caused by cis-regulatory variation in the floral repressor ChFLC, such that genotypes with low-expressing ChFLC alleles show both early flowering and accelerated age-dependent changes in leaf form, including faster leaflet production. We provide evidence that this mechanism coordinates leaf development with reproductive timing and may help to optimize resource allocation to the next generation.
Asunto(s)
Cardamine/genética , Hojas de la Planta/anatomía & histología , Sitios de Carácter Cuantitativo , Alelos , Arabidopsis , Secuencia de Bases , Biodiversidad , Mapeo Cromosómico , Clonación Molecular , Flores , Regulación de la Expresión Génica de las Plantas , Genotipo , Luz , Modelos Genéticos , Datos de Secuencia Molecular , Fenotipo , Plantas Modificadas Genéticamente , Polimorfismo Genético , Semillas , Homología de Secuencia de Ácido NucleicoRESUMEN
In the development of tomato compound leaves, local auxin maxima points, separated by the expression of the Aux/IAA protein SlIAA9/ENTIRE (E), direct the formation of discrete leaflets along the leaf margin. The local auxin maxima promote leaflet initiation, while E acts between leaflets to inhibit auxin response and lamina growth, enabling leaflet separation. Here, we show that a group of auxin response factors (ARFs), which are targeted by miR160, antagonizes auxin response and lamina growth in conjunction with E. In wild-type leaf primordia, the miR160-targeted ARFs SlARF10A and SlARF17 are expressed in leaflets, and SlmiR160 is expressed in provascular tissues. Leaf overexpression of the miR160-targeted ARFs SlARF10A, SlARF10B or SlARF17, led to reduced lamina and increased leaf complexity, and suppressed auxin response in young leaves. In agreement, leaf overexpression of miR160 resulted in simplified leaves due to ectopic lamina growth between leaflets, reminiscent of e leaves. Genetic interactions suggest that E and miR160-targeted ARFs act partially redundantly but are both required for local inhibition of lamina growth between initiating leaflets. These results show that different types of auxin signal antagonists act cooperatively to ensure leaflet separation in tomato leaf margins.
Asunto(s)
Ácidos Indolacéticos/metabolismo , Hojas de la Planta/metabolismo , Proteínas de Plantas/metabolismo , Solanum lycopersicum/metabolismo , Regulación de la Expresión Génica de las Plantas , Solanum lycopersicum/crecimiento & desarrollo , MicroARNs/genética , Hojas de la Planta/genética , Hojas de la Planta/crecimiento & desarrollo , Proteínas de Plantas/genéticaRESUMEN
In seed plants, new axes of growth are established by the formation of meristems, groups of pluripotent cells that maintain themselves and initiate the formation of lateral organs. After embryonic development, secondary shoot meristems form in the boundary zones between the shoot apical meristem and leaf primordia, the leaf axils. In addition, many plant species develop ectopic meristems at different positions of the plant body. In the compound tomato leaf, ectopic meristems can initiate at the base of leaflets, which are delimited by two distinct boundary zones, referred to as the proximal (PLB) and distal (DLB) leaflet boundaries. We demonstrate that the two leaflet boundaries differ from each other and that ectopic meristem formation is strictly limited to the DLB. Our data suggest that the DLB harbours a group of pluripotent cells that seems to be the launching pad for meristem formation. Initiation of these meristems is dependent on the activities of the transcriptional regulators Goblet (Gob) and Lateral suppressor (Ls), specifically expressed in the DLB. Gob and Ls act in hierarchical order, because Ls transcript accumulation is dependent on Gob activity, but not vice versa. Ectopic meristem formation at the DLB is also observed in other seed plants, like Cardamine pratensis, indicating that it is part of a widespread developmental program. Ectopic meristem formation leads to an increase in the number of buds, enhances the capacity for survival and opens the route to vegetative propagation.
Asunto(s)
Regulación del Desarrollo de la Expresión Génica , Hojas de la Planta/genética , Proteínas de Plantas/genética , Solanum lycopersicum/genética , Regulación de la Expresión Génica de las Plantas , Solanum lycopersicum/crecimiento & desarrollo , Solanum lycopersicum/ultraestructura , Meristema/genética , Meristema/crecimiento & desarrollo , Meristema/ultraestructura , Mutación , Fenotipo , Hojas de la Planta/crecimiento & desarrollo , Hojas de la Planta/ultraestructura , Proteínas de Plantas/metabolismo , Brotes de la Planta/genética , Brotes de la Planta/crecimiento & desarrollo , Brotes de la Planta/ultraestructura , Plantas Modificadas Genéticamente , Factores de Transcripción/genética , Factores de Transcripción/metabolismoRESUMEN
485 I. 485 II. 486 III. 491 IV. 491 V. 495 495 References 495 SUMMARY: Boundaries, established and maintained in different regions of the plant body, have diverse functions in development. One role is to separate different cell groups, for example the differentiating cells of a leaf primordium from the pluripotent cells of the apical meristem. Boundary zones are also established during compound leaf development, to separate young leaflets from each other, and in many other positions of the plant body. Recent studies have demonstrated that different boundary zones share similar properties. They are characterized by a low rate of cell divisions and specific patterns of gene expression. In addition, the levels of the plant hormones auxin and brassinosteroids are down-regulated in boundary zones, resulting in a low differentiation level of boundary cells. This feature seems to be crucial for a second important role of boundary zones, the formation of new meristems. The primary shoot meristem, as well as secondary and ectopic shoot meristems, initiate from boundary cells that exhibit competence for meristem formation.
Asunto(s)
Brasinoesteroides/metabolismo , Regulación del Desarrollo de la Expresión Génica , Ácidos Indolacéticos/metabolismo , Meristema/crecimiento & desarrollo , Hojas de la Planta/crecimiento & desarrollo , División Celular , Meristema/citología , Meristema/genética , Hojas de la Planta/citología , Hojas de la Planta/metabolismo , Brotes de la Planta/crecimiento & desarrolloRESUMEN
PREMISE OF THE STUDY: On a compound leaf, leaflet primordia are repetitively formed along the apical-basal axis, with the direction varying among taxa. Why and how the directions vary among species is yet to be solved, although a change in a single factor was proposed to cause the variation. In this study, we compared two species in the Papaveraceae with different directions of leaflet initiation, Chelidonium majus subsp. asiaticum (basipetal) and Eschscholzia californica (acropetal). Because E. californica has been studied in some detail, we focused on C. majus and asked how basipetal pattern is achieved. ⢠METHODS: Since only immature leaf primordial tissue has leaflet-generating competency, we performed histological and gene expression analyses on markers of the tissue maturation state. In addition, we performed a time-course analysis of leaf primordial growth. ⢠KEY RESULTS: Quantitative reverse transcription-PCR analysis demonstrated that a putative regulator of tissue maturation in C. majus, the CINCINNATA homolog, had higher expression in apical parts than in basal parts during the organogenetic phase. In contrast, expression of the CIN homolog was not elevated in either the apical or basal parts in E. californica during the organogenetic phase. ⢠CONCLUSIONS: In C. majus, apical parts of leaf primordia have already lost leaflet-generating competency during the organogenetic phase. We propose that precocious progression of the maturation process instructs basipetal progression of leaflet initiation in C. majus. This is not the mirror image of data on E. californica, which shows the opposite direction in leaflet formation, indicating that variation in direction is not attributable to a change in a single factor.
Asunto(s)
Chelidonium/crecimiento & desarrollo , Regulación del Desarrollo de la Expresión Génica/fisiología , Regulación de la Expresión Génica de las Plantas/fisiología , Hojas de la Planta/crecimiento & desarrollo , Chelidonium/genética , Chelidonium/metabolismo , Filogenia , Hojas de la Planta/genética , Hojas de la Planta/metabolismo , Hojas de la Planta/ultraestructura , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , ARN de Planta/genética , ARN de Planta/metabolismo , Factores de TiempoRESUMEN
To understand the distribution pattern of leaflet traits in compound-leaved along with phyllotaxy, we selected three compound-leaved trees with opposite phyllotaxy in Xiaoxing' an Mountains, Fraxinus mandshurica, Phellodendron amurense, Juglans mandshurica, as the research objects. We measured leaf thickness, leaf area, specific leaf area, leaf dry matter content, palisade tissue thickness, spongy tissue thickness, ratio of palisade tissue thickness to spongy tissue thickness, and carbon content, nitrogen content, phosphorus content of leaflets at different phyllotaxy positions. We analyzed the variation of leaflet traits with phyllotaxy and the influence of phyllotaxy on the inner relationships between leaflet traits. The results showed that the variation of leaflet area, leaflet dry matter content, spongy tissue thickness and ratio of palisade tissue thickness to spongy tissue thickness with the increase of phyllotaxy were mainly divided into three types: increase, decrease, first increase and then decrease. Leaflet thickness, specific leaflet area, palisade tissue thickness, as well as nutrient contents did not change with phyllotaxy. Within compound leaves of three species, the variation coefficients and plasticity index of leaflet thickness, leaflet area, specific leaflet area, leaflet dry matter content, palisade tissue thickness, spongy tissue thickness, ratio of palisade tissue thickness to spongy tissue thickness ranged from 6.1% to 28.6% and from 0.14 to 0.70, respectively. Phyllotaxy had a significant effect on the bivariate correlation between leaflet traits. Specific leaflet area and leaflet dry natter content were negatively correlated in different phyllotaxy positions of F. mandshurica and J. mandshurica. Leaflet nitrogen content and phosphorus content showed a positive correlation in different phyllotaxy positions of F. mandshurica and P. amurense. The first and secondary leaflets (the first leaflets farthest from the base of the petiole) of J. mandshurica showed a conservative strategy, while the seventh and eighth leaflets showed an acquisition strategy. Leaflets of F. mandshurica and P. amurense did not show different ecological strategies.
Asunto(s)
Fraxinus , Juglans , Árboles , Hojas de la Planta , NitrógenoRESUMEN
Epimedium koreanum Nakai, a well-known traditional Chinese medicinal herb, has been widely used to treat osteoporosis and sexual dysfunction for thousands of years. However, due to the decreasing population of East Asian natural resources, yearly output of Epimedium crude herb has been in low supply year by year. In this study, an unusual variety of E. koreanum was discovered in Dunhua, Jilin Province, the northernmost area where this variety was found containing 6 individuals, with three branches that had 27 leaflets, which is much more than the typical leaflet number of 9. Firstly, the novel E. koreanum varety was identified using DNA barcodes. Then, 1171 differentially expressed genes (DEGs) were discovered through parallel RNA-seq analysis between the newly discovered variety and wild type (WT) E. koreanum plant. Furthermore, the results of bioinformatics investigation revealed that 914 positively and 619 negatively correlated genes associated with the number of leaflets. Additionally, based on RNA-Seq and qRT-PCR analysis, two homologous hub TCP genes, which were commonly implicated in plant leaf development, and shown to be up regulated and down regulated in the discovered newly variety, respectively. Thus, our study discovered a novel wild resource for leaf yield rewarding medicinal Epimedium plant breeding, provided insights into the relationship between plant compound leaf formation and gene expression of TCPs transcription factors and other gene candidates, providing bases for creating high yield cultivated Epimedium variety by using further molecular selection and breeding techniques in the future.