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Yang X, Wang Y, Liu TX, Liu Q, Liu J, Lü TF, Yang RX, Guo FX, Wang YZ. CYCLOIDEA-like genes control floral symmetry, floral orientation, and nectar guide patterning. THE PLANT CELL 2023; 35:2799-2820. [PMID: 37132634 PMCID: PMC10396386 DOI: 10.1093/plcell/koad115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 04/07/2023] [Accepted: 04/10/2023] [Indexed: 05/04/2023]
Abstract
Actinomorphic flowers usually orient vertically (relative to the horizon) and possess symmetric nectar guides, while zygomorphic flowers often face horizontally and have asymmetric nectar guides, indicating that floral symmetry, floral orientation, and nectar guide patterning are correlated. The origin of floral zygomorphy is dependent on the dorsoventrally asymmetric expression of CYCLOIDEA (CYC)-like genes. However, how horizontal orientation and asymmetric nectar guides are achieved remains poorly understood. Here, we selected Chirita pumila (Gesneriaceae) as a model plant to explore the molecular bases for these traits. By analyzing gene expression patterns, protein-DNA and protein-protein interactions, and encoded protein functions, we identified multiple roles and functional divergence of 2 CYC-like genes, i.e. CpCYC1 and CpCYC2, in controlling floral symmetry, floral orientation, and nectar guide patterning. CpCYC1 positively regulates its own expression, whereas CpCYC2 does not regulate itself. In addition, CpCYC2 upregulates CpCYC1, while CpCYC1 downregulates CpCYC2. This asymmetric auto-regulation and cross-regulation mechanism might explain the high expression levels of only 1 of these genes. We show that CpCYC1 and CpCYC2 determine asymmetric nectar guide formation, likely by directly repressing the flavonoid synthesis-related gene CpF3'5'H. We further suggest that CYC-like genes play multiple conserved roles in Gesneriaceae. These findings shed light on the repeated origins of zygomorphic flowers in angiosperms.
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Affiliation(s)
- Xia Yang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
| | - Yang Wang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tian-Xia Liu
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qi Liu
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jing Liu
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
| | - Tian-Feng Lü
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
| | - Rui-Xue Yang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Feng-Xian Guo
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yin-Zheng Wang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
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Zhao H, Liao H, Li S, Zhang R, Dai J, Ma P, Wang T, Wang M, Yuan Y, Fu X, Cheng J, Duan X, Xie Y, Zhang P, Kong H, Shan H. Delphinieae flowers originated from the rewiring of interactions between duplicated and diversified floral organ identity and symmetry genes. THE PLANT CELL 2023; 35:994-1012. [PMID: 36560915 PMCID: PMC10015166 DOI: 10.1093/plcell/koac368] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 12/15/2022] [Indexed: 06/17/2023]
Abstract
Species of the tribe Delphinieae (Ranunculaceae) have long been the focus of morphological, ecological, and evolutionary studies due to their highly specialized, nearly zygomorphic (bilaterally symmetrical) spiral flowers with nested petal and sepal spurs and reduced petals. The mechanisms underlying the development and evolution of Delphinieae flowers, however, remain unclear. Here, by conducting extensive phylogenetic, comparative transcriptomic, expression, and functional studies, we clarified the evolutionary histories, expression patterns, and functions of floral organ identity and symmetry genes in Delphinieae. We found that duplication and/or diversification of APETALA3-3 (AP3-3), AGAMOUS-LIKE6 (AGL6), CYCLOIDEA (CYC), and DIVARICATA (DIV) lineage genes was tightly associated with the origination of Delphinieae flowers. Specifically, an AGL6-lineage member (such as the Delphinium ajacis AGL6-1a) represses sepal spur formation and petal development in the lateral and ventral parts of the flower while determining petal identity redundantly with AGL6-1b. By contrast, two CYC2-like genes, CYC2b and CYC2a, define the dorsal and lateral-ventral identities of the flower, respectively, and form complex regulatory links with AP3-3, AGL6-1a, and DIV1. Therefore, duplication and diversification of floral symmetry genes, as well as co-option of the duplicated copies into the preexisting floral regulatory network, have been key for the origin of Delphinieae flowers.
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Affiliation(s)
- Huiqi Zhao
- State Key Laboratory of Systematic and Evolutionary Botany, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Hainan Academy of Agricultural Sciences, Haikou 571100, China
| | - Hong Liao
- State Key Laboratory of Systematic and Evolutionary Botany, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Shuixian Li
- State Key Laboratory of Systematic and Evolutionary Botany, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- China National Botanical Garden, Beijing 100093, China
| | - Rui Zhang
- State Key Laboratory of Systematic and Evolutionary Botany, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Jing Dai
- State Key Laboratory of Systematic and Evolutionary Botany, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Pengrui Ma
- State Key Laboratory of Systematic and Evolutionary Botany, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Tianpeng Wang
- State Key Laboratory of Systematic and Evolutionary Botany, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Meimei Wang
- State Key Laboratory of Systematic and Evolutionary Botany, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- China National Botanical Garden, Beijing 100093, China
| | - Yi Yuan
- State Key Laboratory of Systematic and Evolutionary Botany, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- China National Botanical Garden, Beijing 100093, China
| | - Xuehao Fu
- State Key Laboratory of Systematic and Evolutionary Botany, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
| | - Jie Cheng
- State Key Laboratory of Systematic and Evolutionary Botany, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
| | - Xiaoshan Duan
- State Key Laboratory of Systematic and Evolutionary Botany, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Yanru Xie
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Peng Zhang
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Hongzhi Kong
- State Key Laboratory of Systematic and Evolutionary Botany, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- China National Botanical Garden, Beijing 100093, China
| | - Hongyan Shan
- State Key Laboratory of Systematic and Evolutionary Botany, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
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Advances in Research on the Regulation of Floral Development by CYC-like Genes. Curr Issues Mol Biol 2023; 45:2035-2059. [PMID: 36975501 PMCID: PMC10047570 DOI: 10.3390/cimb45030131] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 02/24/2023] [Accepted: 02/27/2023] [Indexed: 03/06/2023] Open
Abstract
CYCLOIDEA (CYC)-like genes belong to the TCP transcription factor family and play important roles associated with flower development. The CYC-like genes in the CYC1, CYC2, and CYC3 clades resulted from gene duplication events. The CYC2 clade includes the largest number of members that are crucial regulators of floral symmetry. To date, studies on CYC-like genes have mainly focused on plants with actinomorphic and zygomorphic flowers, including Fabaceae, Asteraceae, Scrophulariaceae, and Gesneriaceae species and the effects of CYC-like gene duplication events and diverse spatiotemporal expression patterns on flower development. The CYC-like genes generally affect petal morphological characteristics and stamen development, as well as stem and leaf growth, flower differentiation and development, and branching in most angiosperms. As the relevant research scope has expanded, studies have increasingly focused on the molecular mechanisms regulating CYC-like genes with different functions related to flower development and the phylogenetic relationships among these genes. We summarize the status of research on the CYC-like genes in angiosperms, such as the limited research conducted on CYC1 and CYC3 clade members, the necessity to functionally characterize the CYC-like genes in more plant groups, the need for investigation of the regulatory elements upstream of CYC-like genes, and exploration of the phylogenetic relationships and expression of CYC-like genes with new techniques and methods. This review provides theoretical guidance and ideas for future research on CYC-like genes.
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Floral symmetry: the geometry of plant reproduction. Emerg Top Life Sci 2022; 6:259-269. [PMID: 35994008 PMCID: PMC9472818 DOI: 10.1042/etls20210270] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 07/29/2022] [Accepted: 08/01/2022] [Indexed: 12/23/2022]
Abstract
The flower is an astonishing innovation that arose during plant evolution allowing flowering plants — also known as angiosperms — to dominate life on earth in a relatively short period of geological time. Flowers are formed from secondary meristems by co-ordinated differentiation of flower organs, such as sepals, petals, stamens, and carpels. The position, number and morphology of these flower organs impose a geometrical pattern — or symmetry type — within the flower which is a trait tightly connected to successful reproduction. During evolution, flower symmetry switched from the ancestral poly-symmetric (radial symmetry) to the mono-symmetric (bilateral symmetry) type multiple times, including numerous reversals, with these events linked to co-evolution with pollinators and reproductive strategies. In this review, we introduce the diversity of flower symmetry, trace its evolution in angiosperms, and highlight the conserved genetic basis underpinning symmetry control in flowers. Finally, we discuss the importance of building upon the concept of flower symmetry by looking at the mechanisms orchestrating symmetry within individual flower organs and summarise the current scenario on symmetry patterning of the female reproductive organ, the gynoecium, the ultimate flower structure presiding over fertilisation and seed production.
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