1. Expression and Functional Analyses of Nymphaea caerulea MADS-Box Genes Contribute to Clarify the Complex Flower Patterning of Water Lilies
- Author
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Silvia Moschin, Sebastiano Nigris, Ignacio Ezquer, Simona Masiero, Stefano Cagnin, Enrico Cortese, Lucia Colombo, Giorgio Casadoro, and Barbara Baldan
- Subjects
0106 biological sciences ,Stamen ,MADS-box genes ,Plant Science ,01 natural sciences ,Nymphaea caerulea, flower development, MADS-box genes, flower evolution, ABCDE model, AGAMOUS, early diverging angiosperms, water lily ,SB1-1110 ,03 medical and health sciences ,early diverging angiosperms ,water lily ,AGAMOUS ,flower development ,Nymphaea caerulea ,MADS-box ,030304 developmental biology ,0303 health sciences ,biology ,fungi ,food and beverages ,Plant culture ,15. Life on land ,biology.organism_classification ,ABCDE model ,ABC model of flower development ,Evolutionary biology ,Nymphaeaceae ,Subfunctionalization ,Neofunctionalization ,Petal ,flower evolution ,Caerulea ,010606 plant biology & botany - Abstract
Nymphaeaceae are early diverging angiosperms with large flowers characterized by showy petals and stamens not clearly whorled but presenting a gradual morphological transition from the outer elements to the inner stamens. Such flower structure makes these plant species relevant for studying flower evolution. MADS-domain transcription factors are crucial components of the molecular network that controls flower development. We therefore isolated and characterized MADS-box genes from the water lilyNymphaea caerulea. RNA-seq experiments on floral buds have been performed to obtain the transcript sequences of floral organ identity MADS-box genes. Maximum Likelihood phylogenetic analyses confirmed their belonging to specific MADS-box gene subfamilies. Their expression was quantified by RT-qPCR in all floral organs at two stages of development. Protein interactions among these transcription factors were investigated by yeast-two-hybrid assays. We found especially interesting the involvement of two differentAGAMOUS-likegenes (NycAG1andNycAG2) in the water lily floral components. They were therefore functionally characterized by complementing Arabidopsisagandshp1 shp2mutants. The expression analysis of MADS-box genes across flower development inN. caeruleadescribed a complex scenario made of numerous genes in numerous floral components. Their expression profiles in some cases were in line with what was expected from the ABC model of flower development and its extensions, while in other cases presented new and interesting gene expression patterns, as for instance the involvement ofNycAGL6andNycFL. Although sharing a high level of sequence similarity, the twoAGAMOUS-likegenesNycAG1andNycAG2could have undergone subfunctionalization or neofunctionalization, as only one of them could partially restore theeuAGfunction in Arabidopsisag-3mutants. The hereby illustratedN. caeruleaMADS-box gene expression pattern might mirror the morphological transition from the outer to the inner floral organs, and the presence of transition organs such as the petaloid stamens. This study is intended to broaden knowledge on the role and evolution of floral organ identity genes and the genetic mechanisms causing biodiversity in angiosperm flowers.
- Published
- 2021