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Nakayama H. Leaf form diversity and evolution: a never-ending story in plant biology. JOURNAL OF PLANT RESEARCH 2024:10.1007/s10265-024-01541-4. [PMID: 38592658 DOI: 10.1007/s10265-024-01541-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Accepted: 03/31/2024] [Indexed: 04/10/2024]
Abstract
Leaf form can vary at different levels, such as inter/intraspecies, and diverse leaf shapes reflect their remarkable ability to adapt to various environmental conditions. Over the past two decades, considerable progress has been made in unraveling the molecular mechanisms underlying leaf form diversity, particularly the regulatory mechanisms of leaf complexity. However, the mechanisms identified thus far are only part of the entire process, and numerous questions remain unanswered. This review aims to provide an overview of the current understanding of the molecular mechanisms driving leaf form diversity while highlighting the existing gaps in our knowledge. By focusing on the unanswered questions, this review aims to shed light on areas that require further research, ultimately fostering a more comprehensive understanding of leaf form diversity.
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Affiliation(s)
- Hokuto Nakayama
- Graduate School of Science, Department of Biological Sciences, The University of Tokyo, Science Build. #2, 7-3-1 Hongo Bunkyo-ku, Tokyo, 113-0033, Japan.
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Satterlee JW, Evans LJ, Conlon BR, Conklin P, Martinez-Gomez J, Yen JR, Wu H, Sylvester AW, Specht CD, Cheng J, Johnston R, Coen E, Scanlon MJ. A Wox3-patterning module organizes planar growth in grass leaves and ligules. NATURE PLANTS 2023; 9:720-732. [PMID: 37142751 DOI: 10.1038/s41477-023-01405-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 03/28/2023] [Indexed: 05/06/2023]
Abstract
Grass leaves develop from a ring of primordial initial cells within the periphery of the shoot apical meristem, a pool of organogenic stem cells that generates all of the organs of the plant shoot. At maturity, the grass leaf is a flattened, strap-like organ comprising a proximal supportive sheath surrounding the stem and a distal photosynthetic blade. The sheath and blade are partitioned by a hinge-like auricle and the ligule, a fringe of epidermally derived tissue that grows from the adaxial (top) leaf surface. Together, the ligule and auricle comprise morphological novelties that are specific to grass leaves. Understanding how the planar outgrowth of grass leaves and their adjoining ligules is genetically controlled can yield insight into their evolutionary origins. Here we use single-cell RNA-sequencing analyses to identify a 'rim' cell type present at the margins of maize leaf primordia. Cells in the leaf rim have a distinctive identity and share transcriptional signatures with proliferating ligule cells, suggesting that a shared developmental genetic programme patterns both leaves and ligules. Moreover, we show that rim function is regulated by genetically redundant Wuschel-like homeobox3 (WOX3) transcription factors. Higher-order mutations in maize Wox3 genes greatly reduce leaf width and disrupt ligule outgrowth and patterning. Together, these findings illustrate the generalizable use of a rim domain during planar growth of maize leaves and ligules, and suggest a parsimonious model for the homology of the grass ligule as a distal extension of the leaf sheath margin.
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Affiliation(s)
- James W Satterlee
- School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
| | - Lukas J Evans
- School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
| | - Brianne R Conlon
- School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
| | - Phillip Conklin
- School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
| | | | - Jeffery R Yen
- School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
| | - Hao Wu
- School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
| | - Anne W Sylvester
- School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
- Marine Biological Laboratory, Woods Hole, MA, USA
| | - Chelsea D Specht
- School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
| | - Jie Cheng
- John Innes Centre, Norwich Research Park, Norwich, UK
- State Key Laboratory of Systematic and Evolutionary Botany, Chinese Academy of Sciences, Beijing, China
| | - Robyn Johnston
- School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
- The Elshire Group Ltd., Palmerston North, New Zealand
| | - Enrico Coen
- John Innes Centre, Norwich Research Park, Norwich, UK
| | - Michael J Scanlon
- School of Integrative Plant Science, Cornell University, Ithaca, NY, USA.
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Nakayama H, Leichty AR, Sinha NR. Molecular mechanisms underlying leaf development, morphological diversification, and beyond. THE PLANT CELL 2022; 34:2534-2548. [PMID: 35441681 PMCID: PMC9252486 DOI: 10.1093/plcell/koac118] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 04/13/2022] [Indexed: 05/13/2023]
Abstract
The basic mechanisms of leaf development have been revealed through a combination of genetics and intense analyses in select model species. The genetic basis for diversity in leaf morphology seen in nature is also being unraveled through recent advances in techniques and technologies related to genomics and transcriptomics, which have had a major impact on these comparative studies. However, this has led to the emergence of new unresolved questions about the mechanisms that generate the diversity of leaf form. Here, we provide a review of the current knowledge of the fundamental molecular genetic mechanisms underlying leaf development with an emphasis on natural variation and conserved gene regulatory networks involved in leaf development. Beyond that, we discuss open questions/enigmas in the area of leaf development, how recent technologies can best be deployed to generate a unified understanding of leaf diversity and its evolution, and what untapped fields lie ahead.
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Affiliation(s)
- Hokuto Nakayama
- Graduate School of Science, Department of Biological Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Aaron R Leichty
- Department of Plant Biology, University of California Davis, Davis, California 95616, USA
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Nukazuka A, Yamaguchi T, Tsukaya H. A Role for Auxin in Triggering Lamina Outgrowth of Unifacial Leaves. PLANT PHYSIOLOGY 2021; 186:1013-1024. [PMID: 33620494 PMCID: PMC8195525 DOI: 10.1093/plphys/kiab087] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 01/31/2021] [Indexed: 05/26/2023]
Abstract
A common morphological feature of typical angiosperms is the patterning of lateral organs along primary axes of asymmetry-a proximodistal, a mediolateral, and an adaxial-abaxial axis. Angiosperm leaves usually have distinct adaxial-abaxial identity, which is required for the development of a flat shape. By contrast, many unifacial leaves, consisting of only the abaxial side, show a flattened morphology. This implicates a unique mechanism that allows leaf flattening independent of adaxial-abaxial identity. In this study, we report a role for auxin in outgrowth of unifacial leaves. In two closely related unifacial-leaved species of Juncaceae, Juncus prismatocarpus with flattened leaves, and Juncus wallichianus with transversally radialized leaves, the auxin-responsive gene GLYCOSIDE HYDROLASE3 displayed spatially different expression patterns within leaf primordia. Treatment of J. prismatocarpus seedlings with exogenous auxin or auxin transport inhibitors, which disturb endogenous auxin distribution, eliminated leaf flatness, resulting in a transversally radialized morphology. These treatments did not affect the radialized morphology of leaves of J. wallichianus. Moreover, elimination of leaf flatness by these treatments accompanied dysregulated expression of genetic factors needed to specify the leaf central-marginal polarity in J. prismatocarpus. The findings imply that lamina outgrowth of unifacial leaves relies on proper placement of auxin, which might induce initial leaf flattening and subsequently act to specify leaf polarity, promoting further flattening growth of leaves.
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Affiliation(s)
- Akira Nukazuka
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Takahiro Yamaguchi
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Hirokazu Tsukaya
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
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Yin X, Tsukaya H. A Pulse-chase EdU Method for Detection of Cell Division Orientation in Arabidopsis and Juncus prismatocarpus Leaf Primordia. Bio Protoc 2021; 11:e3882. [PMID: 33732770 DOI: 10.21769/bioprotoc.3882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 11/04/2020] [Accepted: 11/06/2020] [Indexed: 11/02/2022] Open
Abstract
In plants, the morphological diversity of leaves is largely determined by cell division, especially cell division orientation. Whereas cell division itself is easily monitored, the detection and quantification of cell division orientation are difficult. The few existing methods for detection and quantification of cell division orientation are either inefficient or laborious. Here, we describe a pulse-chase strategy using a 5-ethynyl-2'-deoxyuridine (EdU) labeling assay. Plant tissues are first incubated with EdU for a short period (pulse), followed by a long incubation without EdU (chase). Using this method, the positions of daughter cells are easily detected and can be used to quantify cell division orientation. Our protocol is rapid and very efficient for quantitative analysis of cell division orientation, and can be applied to both model and non-model plant species. Graphic abstract: Plant cell division pairs clearly visualized by a pulse-chase EdU method.
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Affiliation(s)
- Xiaofeng Yin
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan.,International Research Fellow of Japan Society for the Promotion of Science, Tokyo, Japan
| | - Hirokazu Tsukaya
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
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Manuela D, Xu M. Patterning a Leaf by Establishing Polarities. FRONTIERS IN PLANT SCIENCE 2020; 11:568730. [PMID: 33193497 PMCID: PMC7661387 DOI: 10.3389/fpls.2020.568730] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 09/30/2020] [Indexed: 05/14/2023]
Abstract
Leaves are the major organ for photosynthesis in most land plants, and leaf structure is optimized for the maximum capture of sunlight and gas exchange. Three polarity axes, the adaxial-abaxial axis, the proximal-distal axis, and the medial-lateral axis are established during leaf development to give rise to a flattened lamina with a large area for photosynthesis and blades that are extended on petioles for maximum sunlight. Adaxial cells are elongated, tightly packed cells with many chloroplasts, and their fate is specified by HD-ZIP III and related factors. Abaxial cells are rounder and loosely packed cells and their fate is established and maintained by YABBY family and KANADI family proteins. The activities of adaxial and abaxial regulators are coordinated by ASYMMETRIC LEAVES2 and auxin. Establishment of the proximodistal axis involves the BTB/POZ domain proteins BLADE-ON-PETIOLE1 and 2, whereas homeobox genes PRESSED FLOWER and WUSCHEL-RELATED HOMEOBOX1 mediate leaf development along the mediolateral axis. This review summarizes recent advances in leaf polarity establishment with a focus on the regulatory networks involved.
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Affiliation(s)
| | - Mingli Xu
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
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