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Adaxial domain in compound leaves from various plant species.a, b, Pinnate compound leaf from F. americana. c–e, Peltately palmate compound leaf from S. actinophylla, showing leaflets (d) and petiole (e). f–i, Non-peltately palmate leaves from V. cannabifolia (f, g) and R. lancea (h, i). j–m, Pinnate compound leaves from A. hindisii (j) L. coccinea (k), S. gaudichaudii (l) and F. americana (m). n–q, Non-peltately palmate leaves from D. pentaphylla (n), L. albifrons (o), V. cannabifolia (p) and R. lancea (q). r–u, Peltately palmate compound leaves from P. aquatica (r), A. pentaphylla (s), O. regnellii (t) and S. actinophylla (u). Asterisks, leaflets; AD, adaxial domain; Pe, petiole; R, rachis. Scale bars, 1 cm (a, c, f, h, j–u); 2 mm (b, d, e, g, i).
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Diverse leaf forms in nature can be categorized as simple or compound. Simple leaves, such as those of petunia, have a single unit of blade, whereas compound leaves, such as those of tomato, have several units of blades called leaflets. Compound leaves can be pinnate, with leaflets arranged in succession on a rachis, or palmate, with leaflets clust...
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... leaves were similar in architecture. Certain leaves (non- peltately palmate compound) had a well-defined adaxial domain throughout the petiole. Leaflets were clustered at the tip of the petiole, but no leaflets were formed in the region where the adaxial domain existed at the tip of the petiole ( Fig. 2f-i, red ...
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... showed distinct ab-adaxial symmetry in the petioles of pinnate (Acacia hindisii, Senna gaudichaudii, Leea coccinea and F. americana; Fig. 2j-m) or non-peltately palmate (Dioscorea pentaphylla, Lupinus albifrons, Vitex cannabifolia and Rhus lancea; Fig. 2n-q) compound leaves; however, peltately palmate compound leaves produced leaflets all around the tip of the petiole (such as Schefflera, Fig. 2c-e). The petioles of peltately palmate compound leaves (such as Pachira ...
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... showed distinct ab-adaxial symmetry in the petioles of pinnate (Acacia hindisii, Senna gaudichaudii, Leea coccinea and F. americana; Fig. 2j-m) or non-peltately palmate (Dioscorea pentaphylla, Lupinus albifrons, Vitex cannabifolia and Rhus lancea; Fig. 2n-q) compound leaves; however, peltately palmate compound leaves produced leaflets all around the tip of the petiole (such as Schefflera, Fig. 2c-e). The petioles of peltately palmate compound leaves (such as Pachira aquatica, Akebia pentaphylla, Oxalis regnellii and Schefflera actinophylla; Fig. 2r-u) were radially symmetrical with ...
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... petioles of pinnate (Acacia hindisii, Senna gaudichaudii, Leea coccinea and F. americana; Fig. 2j-m) or non-peltately palmate (Dioscorea pentaphylla, Lupinus albifrons, Vitex cannabifolia and Rhus lancea; Fig. 2n-q) compound leaves; however, peltately palmate compound leaves produced leaflets all around the tip of the petiole (such as Schefflera, Fig. 2c-e). The petioles of peltately palmate compound leaves (such as Pachira aquatica, Akebia pentaphylla, Oxalis regnellii and Schefflera actinophylla; Fig. 2r-u) were radially symmetrical with vascular bundles arranged in a ring, consistent with complete abaxialization of this region. In a survey of 25 angiosperm families, 289 species with ...
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... albifrons, Vitex cannabifolia and Rhus lancea; Fig. 2n-q) compound leaves; however, peltately palmate compound leaves produced leaflets all around the tip of the petiole (such as Schefflera, Fig. 2c-e). The petioles of peltately palmate compound leaves (such as Pachira aquatica, Akebia pentaphylla, Oxalis regnellii and Schefflera actinophylla; Fig. 2r-u) were radially symmetrical with vascular bundles arranged in a ring, consistent with complete abaxialization of this region. In a survey of 25 angiosperm families, 289 species with pinnate compound and 153 species with non- peltately palmate compound leaves showed an adaxial domain extending from the tip of the leaf to the bottom. By ...
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... a survey of 25 angiosperm families, 289 species with pinnate compound and 153 species with non- peltately palmate compound leaves showed an adaxial domain extending from the tip of the leaf to the bottom. By contrast, in 56 different species with peltately palmate compound leaves, leaflets were produced all around the tip of petiole and the petiole lacked an adaxial domain (Supplementary Fig. 2a). This suggests that absence of the adaxial domain in the proximal region of petiole (petiole abaxialization) is important for generating peltately palmate com- pound leaves. ...
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... PHAN orthologues from monocot and dicot species showed high conservation of amino acid sequence ( Supplementary Fig. 2b, c). The PHAN orthologues always formed a monophyletic clade, which was distinct from all other known MYB proteins (data not shown). ...
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... V. cannabifolia, S. actinophylla, A. hindisii, P. aquatica and F. americana) were cloned by PCR with the following degenerate primers, designed on the basis of available PHAN orthologue sequences: DePHAN1, 5 0 -CACGGNAACAARTGG AARAA-3 0 ; DePHAN2, 5 0 -GCTTCRATYTCCTCCATYTT-3 0 . We aligned nucleotide and amino acid sequences by ClustalX ( Supplementary Fig. 2c) and carried out parsimony analyses by PAUP4 and McClade. ...
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... cardiac septal defects (CSDs) are common, the precise molecular mechanisms for cardiac septal closure in humans remain to be elucidated. Mutations in NKX2-5 have been identified in individuals with CSDs and conduction abnormalities, whereas individuals with Holt-Oram syndrome (HOS)-characterized by CSDs, conduction abnormalities and limb anomalies-have point mutations in TBX5 (refs 2, 8, 9). ...
Similar publications
MYB-type transcription factors contain the conserved MYB DNA-binding domain of approximately 50 amino acids and are involved in the regulation of many aspects of plant growth, development, metabolism and stress responses. From soybean plants, we identified 156 GmMYB genes using our previously obtained 206 MYB unigenes, and 48 were found to have ful...
Citations
... A key insight has been that flatness is intrinsically linked to adaxial-abaxial (ad-ab; top-bottom) polarity 1 . Formation of a flat leaf requires a planar polarity boundary and any deviations from this ad-ab domain organization during primordium growth lead to widely diverse leaf shapes [2][3][4][5][6][7] . Indeed, recent models illustrate how regional growth patterns guided by ad-ab gene expression can account for the emergence of diverse organ forms from an initially similar primordium 5,7 . ...
... However, with deviations that vary the system wavelength relative to the tissue size, Turing systems will generate a range of distinct spatial patterns 25 . This point is of note, given that small shifts in ad-ab gene expression can translate into widely diverse leaf shapes [1][2][3][4][5][6][7] . To establish how variations in system wavelength might manifest at the organ level, we performed a morpho-sensitivity analysis of the LPM on the growing cellular template, using a parameter scale of k 2 and k 5 (Supplementary Note 4.3). ...
... As a result, within a smaller mutant primordium, the effects of a shortened wavelength may manifest as a seemingly longer wavelength phenotype. Finally, Turing dynamics, as illustrated by the LPM's repertoire of spatial patterns, can account for the patterns of ad-ab gene expression observed in plant species exhibiting unifacial, peltate or pitcher-shaped leaves 2,4,6,41 . Indeed, recent findings revealed that the formation of carnivorous traps in Utricularia gibba arises from a shift in ad-ab gene expression from a 'bipolar linear' to a 'polar shift up' pattern 5 . ...
The formation of a flat and thin leaf presents a developmentally challenging problem, requiring intricate regulation of adaxial–abaxial (top–bottom) polarity. The patterning principles controlling the spatial arrangement of these domains during organ growth have remained unclear. Here we show that this regulation in Arabidopsis thaliana is achieved by an organ-autonomous Turing reaction‐diffusion system centred on mobile small RNAs. The data illustrate how Turing dynamics transiently instructed by prepatterned information is sufficient to self‐sustain properly oriented polarity in a dynamic, growing organ, presenting intriguing parallels to left–right patterning in the vertebrate embryo. Computational modelling demonstrates that this self-organizing system continuously adapts to coordinate the robust planar polarity of a flat leaf while affording flexibility to generate the tissue patterns of evolutionarily diverse organ shapes. Our findings identify a small-RNA-based Turing network as a dynamic regulator of organ polarity that accounts for leaf shape diversity at the level of the individual organ, plant or species.
... Leaves are scientifical ciencclassified into two categories based on the number of leaflets and the structure of the leaf: simple leaves and complex leaves with many leaflets. A compound leaf, distinguished by its potential to take on many forms such as pinnate and palmate compound leaves, is made up of numerous discontinuous leaf units attached to the rachis and petiole, as opposed to a simple leaf, which is a single unit (Kim et al., 2003). Each leaflet in a complex leaf provides the same photosynthetic function as a simple leaf. ...
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.
... Similarly, the adaxial and abaxial regions are differentiated molecularly by region-specific expression of multiple genes (Satterlee & Scanlon, 2019). As inferred from studies in the monocot Zea mays and the dicot Arabdopsis thaliana, orthologs of AS1, AS2 (PHAN), and HD-ZIP III are expressed adaxially (Bowman et al., 2002;Byrne et al., 2000;Garcia et al., 2006;Hay et al., 2006;Huang et al., 2006;Kim et al., 2003;Li et al., 2005;Ueno et al., 2007;Waites & Hudson, 1995), whereas ETTIN/ARF3 and KANADI are expressed abaxially (Emery et al., 2003;Eshed et al., 2004;Izhaki & Bowman, 2007;Mallory et al., 2004;Moon & Hake, 2011;Tsiantis & Hay, 2003). The adaxial and abaxial defining proteins also negatively regulate the expression of the alternative genes, thereby maintaining the molecularly defined domains. ...
... However, in flattened leaved Sansevieria species, there is no differentiation in stomatal distribution on either side of the leaf, there is no distinct adaxial/abaxial differentiation in the mesophyll, and the vascular bundles are arranged such that the phloem faces the adjacent leaf surface or the leaf margin(Koller & Rost, 1988). As such, even in laminar Sansevieria species, there is no strong adaxial/abaxial differentiation as is found in other monocot and eudicot leaves.Previous seminal studies on leaf development identified key axispolarity genes that distinguished adaxial and abaxial domains(Bowman et al., 2002;Canales et al., 2005;Kim et al., 2003;McConnell et al., 2001;McConnell & Barton, 1998;Prigge et al., 2005;Waites et al., 1998;Williams et al., 2005). Leaf primordia originate when the MYB protein PHAN suppresses KNOX protein suppression of cell differentiation and establishes adaxial polarity on the primordium. ...
Planar structures dramatically increase the surface-area-to-volume ratio, which is critically important for multicellular organisms. In this study, we utilize naturally occurring phenotypic variation among three Sansivieria species (Asperagaceae) to investigate leaf margin expression patterns that are associated with mediolateral and adaxial/abaxial development. We identified differentially expressed genes (DEGs) between center and margin leaf tissues in two planar-leaf species Sansevieria subspicata and Sansevieria trifasciata and compared these with expression patterns within the cylindrically leaved Sansevieria cylindrica. Two YABBY family genes, homologs of FILAMENTOUS FLOWER and DROOPING LEAF, are overexpressed in the center leaf tissue in the planar-leaf species and in the tissue of the cylindrical leaves. As mesophyll structure does not indicate adaxial versus abaxial differentiation, increased leaf thickness results in more water-storage tissue and enhances resistance to aridity. This suggests that the cylindrical-leaf in S. cylindrica is analogous to the central leaf tissue in the planar-leaf species. Furthermore, the congruence of the expression patterns of these YABBY genes in Sansevieria with expression patterns found in other unifacial monocot species suggests that patterns of parallel evolution may be the result of similar solutions derived from a limited developmental toolbox.
... Leaf functional traits are crucial in ecosystem services (Kissling et al. 2019) and are directly linked to the performance of photosynthesis and respiration (Xiong and Jiao 2019). The compound leaves of plants result from the subdivision of simple leaves into individual leaflets (Sinha 1997, Kim et al. 2003. Each leaflet of a compound leaf is the main photosynthetic organ of compound leaf plants (Oliveira et al. 2017). ...
Background:
Here, we present data collected from the Qinghai-Tibet Plateau that describes the variation of leaf functional traits across 32 plant species and could be used to investigate plant community functioning and predict the impact of climate change on biogeochemical cycles. The sampling area is located in Huangshui River Valley, in the southeast of Qinghai Province, China (36° 19' to 36° 53' N, 100° 59' to 102° 48' E). The area contains an alpine meadow typical of the Qinghai-Tibet Plateau.
New information:
This dataset includes field survey data on the functional properties of compound leaves from herbaceous species in the Huangshui River Basin of Qinghai Province, China, at altitudes from 1800 m to 4000 m in the summer of 2021. Data were collected from 326 plots, including 646 data points of compound leaf plants, spanning 32 compound leaf plant species belonging to 14 genera and four families. The study species were chosen from 47 families, 165 genera and 336 species present in the plots and all compound leaf plants were chosen within each plot. We picked the parts containing leaves, petioles and rachis from the study plants and separated the leaves from the plants. The cut compound leaf part was a leaflet, while the petiole and rachis were linear elements. The dataset includes information about the leaflet trait variation (i.e. leaflet area, leaflet dry mass, specific leaflet area and leaflet nitrogen content per unit dry mass) and linear elements' biomass and nitrogen content per unit dry mass (i.e. both petiole and rachis) of 646 compound leaves. This dataset can be used to analyse the evolution of leaf traits and the basic functioning of ecosystems. Moreover, the dataset provides an important basis for studying the species distribution and protection of biodiversity of the Qinghai-Tibet Plateau and evaluating ecosystem services. These data also support the high-quality development of the Yellow River Basin and have empirical and practical value for alpine biodiversity protection and ecosystem management.
... Besides, there are some genes regulating the leaf complexity on the transcriptional level. PHANTASTICA (SlPHAN), containing an MYB-domain protein, can regulate leaflet formation in tomatoes (Kim et al., 2003a). The expression pattern indicated that SlPHAN was expressed throughout the entire adaxial side of the leaf primordium and formed pinnate compound leaves (Kim et al., 2003a). ...
... PHANTASTICA (SlPHAN), containing an MYB-domain protein, can regulate leaflet formation in tomatoes (Kim et al., 2003a). The expression pattern indicated that SlPHAN was expressed throughout the entire adaxial side of the leaf primordium and formed pinnate compound leaves (Kim et al., 2003a). The increased expression level of SlPHAN also can result in a variety of leaf morphologies, from simple, ternate to compound leaves (Zoulias et al., 2012). ...
Leaf morphology can affect the development and yield of plants by regulating plant architecture and photosynthesis. Several factors can determine the final leaf morphology, including the leaf complexity, size, shape, and margin type, which suggests that leaf morphogenesis is a complex regulation network. The formation of diverse leaf morphology is precisely controlled by gene regulation on translation and transcription levels. To further reveal this, more and more genome data has been published for different kinds of vegetable crops and advanced genotyping approaches have also been applied to identify the causal genes for the target traits. Therefore, the studies on the molecular regulation of leaf morphogenesis in vegetable crops have also been largely improved. This review will summarize the progress on identified genes or regulatory mechanisms of leaf morphogenesis and development in vegetable crops. These identified markers can be applied for further molecular-assisted selection (MAS) in vegetable crops. Overall, the review will contribute to understanding the leaf morphology of different crops from the perspective of molecular regulation and shortening the breeding cycle for vegetable crops.
... Although PHAN and its orthologues are uniformly expressed in young leaf primordia of respective species, their roles in adaxial specification are not strictly conserved. The knockdown of PHAN orthologues can lead to abaxialization in tomato (LePHAN) (Kim et al., 2003) but not in maize (RS2) (Timmermans et al., 1999) or Arabidopsis (AS1) (Byrne et al., 2000). In addition, KANADI (KAN) gene, encoding a transcription factor containing MYB-like GARP DNA binding domain, promotes abaxial domain (Kerstetter et al., 2001). ...
The leaf type of a plant determines its photosynthetic efficiency and adaptation to the environment. The normal leaves of modern Ginkgo biloba, which is known as a “living fossil” in gymnosperm, evolved from needle-like to fan-shaped with obvious dichotomous venation. However, a newly discovered Ginkgo variety “SongZhen” have different leaf types on a tree, including needle-, trumpet-, strip-, and deeply split fan-shaped leaves. In order to explore the mechanism in forming these leaf types, the microscopy of different leaf types and transcriptome analysis of apical buds of branches with normal or abnormal leaves were performed. We found that the normal leaf was in an intact and unfolded fan shape, and the abnormal leaf was basically split into two parts from the petiole, and each exhibited different extent of variation. The needle-type leaves were the extreme, having no obvious palisade and spongy tissues, and the phloem cells were scattered and surrounded by xylem cells, while the trumpet-type leaves with normal vascular bundles curled inward to form a loop from the abaxial to adaxial side. The other type of leaves had the characteristics among needle-type, trumpet-type, or normal leaves. The transcriptome analysis and quantitative PCR showed that the genes related to abaxial domain were highly expressed, while the adaxial domain promoting genes were decreasingly expressed in abnormal-type leaf (ANL) buds and abnormal leaves, which might lead to the obvious abaxialized leaves of “SongZhen.” In addition, the low expression of genes related to leaf boundary development in ANL buds indicated that single- or double-needle (trumpet) leaves might also be due to the leaf tissue fusion. This study provides an insight into the mechanism of the development of the abnormal leaves in “SongZhen” and lays a foundation for investigating the molecular mechanism of the leaf development in gymnosperms.
... C. hirsuta chas1 mutants have an altered expression pattern of KNOX I genes in leaf primordia, leading to an increased leaflet production. In tomatoes, down-regulation of ARP results in a switch from pinnate into peltately palmate compound leaves with abaxialized petioles and reduced leaflet number (Kim et al., 2003). Loss-of-function of the pea ARP ortholog CRISPA causes various leaf abnormalities, including crisp leaf organs, narrowing leaflets, the curvature of petiole and rachis, and ectopic stipules on its petiole-rachis axis which is also associated with ectopic KNOX I genes expression (Tattersall et al., 2005). ...
Simple and compound which are the two basic types of leaves are distinguished by the pattern of the distribution of blades on the petiole. Compared to simple leaves comprising a single blade, compound leaves have multiple blade units and exhibit more complex and diverse patterns of organ organization, and the molecular mechanisms underlying their pattern formation are receiving more and more attention in recent years. Studies in model legume Medicago truncatula have led to an improved understanding of the genetic control of the compound leaf patterning. This review is an attempt to summarize the current knowledge about the compound leaf morphogenesis of M. truncatula, with a focus on the molecular mechanisms involved in pattern formation. It also includes some comparisons of the molecular mechanisms between leaf morphogenesis of different model species and offers useful information for the molecular design of legume crops.
... It is widely used for detecting environmental toxins and evaluating drug toxicity due to ease of genetic manipulation, transparency, small size, low breeding and maintenance costs, and the ability to survive without active circulation in early development. The early development marker genes of zebrafish's heart are vmhc (Gong et al., 2019;Huang et al., 2018c;Park et al., 2009;Targoff et al., 2013;Wang et al., 2019b), nppa (Abraham et al., 2009;Deschepper et al., 2001;Grassini et al., 2018;Houweling et al., 2005), myh6 (Huang et al., 2018c;Singleman and Holtzman, 2012), and gata4 (Gong et al., 2019;Han et al., 2019;Huang et al., 2013;Kim et al., 2003;Park et al., 2009;Qian et al., 2017;Takayasu et al., 2008), nkx2.5 (Burcu et al., 2013;Han et al., 2019;Huang et al., 2018c;Huang et al., 2019;Targoff et al., 2013;Wang et al., 2019b), tbx5 (Sanchez-Iranzo et al., 2018Zhao et al., 2015), tbx2b (Huang et al., 2018a;Huang et al., 2018b;Huang et al., 2018c) are the transcriptional factors. These have been clearly expressed in zebrafish, which is of great help in studying the toxicological mechanism of zebrafish. ...
Oxadiazon-Butachlor (OB) is a widely used herbicide for controlling most annual weeds in rice fields. However, its potential toxicity in aquatic organisms has not been evaluated so far. We used the zebrafish embryo model to assess the toxicity of OB, and found that it affected early cardiac development and caused extensive cardiac damage. Mechanistically, OB significantly increased oxidative stress in the embryos by inhibiting antioxidant enzymes that resulted in excessive production of reactive oxygen species (ROS), eventually leading to cardiomyocyte apoptosis. In addition, OB also inhibited the WNT signaling pathway and downregulated its target genes includinglef1, axin2 and β-catenin. Reactivation of this pathway by the Wnt activator BML-284 and the antioxidant astaxanthin rescued the embryos form the cardiotoxic effects of OB, indicating that oxidative stress, and inhibition of WNT target genes are the mechanistic basis of OB-induced damage in zebrafish. Our study shows that OB exposure causes cardiotoxicity in zebrafish embryos and may be potentially toxic to other aquatic life and even humans.
... The subsequent cloning of phan identified a loss-of-function mutation in a MYB-domain transcription factor-encoding gene as responsible for the phenotype [34]. PHAN orthologs are described in maize, Arabidopsis, tobacco, tomato, and pea [10,12,13,[35][36][37][38][39]. Despite the high degree of sequence conservation among the PHAN orthologs, the phan phenotype differs across species. ...
Leaves are initiated as lateral outgrowths from shoot apical meristems throughout the vegetative life of the plant. To achieve proper developmental patterning, cell-type specification and growth must occur in an organized fashion along the proximodistal (base-to-tip), mediolateral (central-to-edge), and adaxial–abaxial (top-bottom) axes of the developing leaf. Early studies of mutants with defects in patterning along multiple leaf axes suggested that patterning must be coordinated across developmental axes. Decades later, we now recognize that a highly complex and interconnected transcriptional network of patterning genes and hormones underlies leaf development. Here, we review the molecular genetic mechanisms by which leaf development is coordinated across leaf axes. Such coordination likely plays an important role in ensuring the reproducible phenotypic outcomes of leaf morphogenesis.
... The ectopic expression of class I KNOX, which includes STM and KN1 genes, has been shown to result in complex leaves (Hareven et al. 1996;Janssen et al. 1998); similarly, the downregulation of KNOX has been shown to change the morphology from compound to simple in Cardamine hirsuta L. (Hay and Tsiantis 2006). Changes in the expression domain or the downregulation of PHANTASTICA (PHAN; an ortholog of AS1) were enough to change a pinnately compound leaf into palmately compound leaf (Kim et al. 2003). Likewise, disruption in CUC2 expression leads to leaves with smooth margins . ...
... In several species, differential expression patterns of AS1 and KNOX genes are reported to be associated with leaf form variation. Kim et al. (2003) and Kim and Sinha (2003) showed that a simple downregulation of the AS1 ortholog PHAN gene was sufficient to produce leaf form variation from pinnately compound to palmately compound in Lycopersicon esculentum Mill. (tomato) and Antirrhinum spp. ...
... In several species, differential expression patterns of AS1 and KNOX genes are reported to be associated with leaf form variation. Kim et al. (2003) and Kim and Sinha (2003) showed that a simple downregulation of the AS1 ortholog PHAN gene was sufficient to produce leaf form variation from pinnately compound to palmately compound in Lycopersicon esculentum Mill. (tomato) and Antirrhinum spp. ...
Simple to compound leaves occur in the Viola albida complex, which comprises the simple, finely serrate leaves of V. albida Palib., the deeply lobed leaves of V. albida var. takahashii (Nakai) Nakai, and the compound leaves of Viola chaerophylloides (Regel) W. Becker. To identify a correlation between the different leaf forms and the expression of several key genes with roles in leaf morphogenesis, the distinct leaf forms occurring within these species were generated by tissue culture of the V. chaerophylloides petiole, for comparison with wild-type leaves. Compound leaves were generally formed from a petiole explant taken close to the leaf blade, whereas simple leaves resulted from petiole explants taken close to the petiole base. KNOTTED-1 (VaKN1), SHOOTMERISTEMLESS (VaSTM), CUP-SHAPED COTYLEDON-2 (VaCUC2), and ASYMMETRIC LEAVES 1 (VaAS1), which are known to play key roles during compound leaf patterning and morphogenesis, were isolated and multiple sequence alignment revealed that there was no sequence variation at the amino acid level within each gene and between the three varieties. Phylogenetic analysis confirmed that the isolated genes were homologous to KN, STM, CUC2, and AS1. The expression of VaKN1, VaSTM, and VaCUC2 was significantly elevated in the in vitro-cultured deeply lobed and compound leaves, as well as in V. chaerophylloides and V. albida var. takahashii plants, but was very low in the in vitro-cultured simple leaves and V. albida plants. These findings demonstrated that elevated transcripts of VaKN1, VaSTM, and VaCUC2 lead to the development of compound and deeply lobed leaves in the V. albida complex.
