Functional analysis of B and C class floral organ genes in spinach demonstrates their role in sexual dimorphism
<p>Abstract</p> <p>Background</p> <p>Evolution of unisexual flowers entails one of the most extreme changes in plant development. Cultivated spinach, <it>Spinacia oleracea </it>L., is uniquely suited for the study of unisexual flower development as it is dio...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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BMC
2010-03-01
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| Series: | BMC Plant Biology |
| Online Access: | http://www.biomedcentral.com/1471-2229/10/46 |
| _version_ | 1811310878388125696 |
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| author | Jovanovic Maja Sather D Noah Golenberg Edward M |
| author_facet | Jovanovic Maja Sather D Noah Golenberg Edward M |
| author_sort | Jovanovic Maja |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p>Evolution of unisexual flowers entails one of the most extreme changes in plant development. Cultivated spinach, <it>Spinacia oleracea </it>L., is uniquely suited for the study of unisexual flower development as it is dioecious and it achieves unisexually by the absence of organ development, rather than by organ abortion or suppression. Male staminate flowers lack fourth whorl primordia and female pistillate flowers lack third whorl primordia. Based on theoretical considerations, early inflorescence or floral organ identity genes would likely be directly involved in sex-determination in those species in which organ initiation rather than organ maturation is regulated. In this study, we tested the hypothesis that sexual dimorphism occurs through the regulation of B class floral organ gene expression by experimentally knocking down gene expression by viral induced gene silencing.</p> <p>Results</p> <p>Suppression of B class genes in spinach resulted in the expected homeotic transformation of stamens into carpels but also affected the number of perianth parts and the presence of fourth whorl. Phenotypically normal female flowers developed on <it>SpPI</it>-silenced male plants. Suppression of the spinach C class floral organ identity gene, <it>SpAG</it>, resulted in loss of reproductive organ identity, and indeterminate flowers, but did not result in additional sex-specific characteristics or structures. Analysis of the genomic sequences of both <it>SpAP3 </it>and <it>SpPI </it>did not reveal any allelic differences between males and females.</p> <p>Conclusion</p> <p>Sexual dimorphism in spinach is not the result of homeotic transformation of established organs, but rather is the result of differential initiation and development of the third and fourth whorl primordia. <it>SpAG </it>is inferred to have organ identity and meristem termination functions similar to other angiosperm C class genes. In contrast, while <it>SpPI </it>and <it>SpAP3 </it>resemble other angiosperms in their essential functions in establishing stamen identity, they also appear to have an additional function in regulating organ number and identity outside of the third whorl. We present a model for the evolution of dioecy in spinach based on the regulation of B class expression.</p> |
| first_indexed | 2024-04-13T10:06:49Z |
| format | Article |
| id | doaj.art-cdedbc2989bd46458fdf2736ada1f1e6 |
| institution | Directory Open Access Journal |
| issn | 1471-2229 |
| language | English |
| last_indexed | 2024-04-13T10:06:49Z |
| publishDate | 2010-03-01 |
| publisher | BMC |
| record_format | Article |
| series | BMC Plant Biology |
| spelling | doaj.art-cdedbc2989bd46458fdf2736ada1f1e62022-12-22T02:51:03ZengBMCBMC Plant Biology1471-22292010-03-011014610.1186/1471-2229-10-46Functional analysis of B and C class floral organ genes in spinach demonstrates their role in sexual dimorphismJovanovic MajaSather D NoahGolenberg Edward M<p>Abstract</p> <p>Background</p> <p>Evolution of unisexual flowers entails one of the most extreme changes in plant development. Cultivated spinach, <it>Spinacia oleracea </it>L., is uniquely suited for the study of unisexual flower development as it is dioecious and it achieves unisexually by the absence of organ development, rather than by organ abortion or suppression. Male staminate flowers lack fourth whorl primordia and female pistillate flowers lack third whorl primordia. Based on theoretical considerations, early inflorescence or floral organ identity genes would likely be directly involved in sex-determination in those species in which organ initiation rather than organ maturation is regulated. In this study, we tested the hypothesis that sexual dimorphism occurs through the regulation of B class floral organ gene expression by experimentally knocking down gene expression by viral induced gene silencing.</p> <p>Results</p> <p>Suppression of B class genes in spinach resulted in the expected homeotic transformation of stamens into carpels but also affected the number of perianth parts and the presence of fourth whorl. Phenotypically normal female flowers developed on <it>SpPI</it>-silenced male plants. Suppression of the spinach C class floral organ identity gene, <it>SpAG</it>, resulted in loss of reproductive organ identity, and indeterminate flowers, but did not result in additional sex-specific characteristics or structures. Analysis of the genomic sequences of both <it>SpAP3 </it>and <it>SpPI </it>did not reveal any allelic differences between males and females.</p> <p>Conclusion</p> <p>Sexual dimorphism in spinach is not the result of homeotic transformation of established organs, but rather is the result of differential initiation and development of the third and fourth whorl primordia. <it>SpAG </it>is inferred to have organ identity and meristem termination functions similar to other angiosperm C class genes. In contrast, while <it>SpPI </it>and <it>SpAP3 </it>resemble other angiosperms in their essential functions in establishing stamen identity, they also appear to have an additional function in regulating organ number and identity outside of the third whorl. We present a model for the evolution of dioecy in spinach based on the regulation of B class expression.</p>http://www.biomedcentral.com/1471-2229/10/46 |
| spellingShingle | Jovanovic Maja Sather D Noah Golenberg Edward M Functional analysis of B and C class floral organ genes in spinach demonstrates their role in sexual dimorphism BMC Plant Biology |
| title | Functional analysis of B and C class floral organ genes in spinach demonstrates their role in sexual dimorphism |
| title_full | Functional analysis of B and C class floral organ genes in spinach demonstrates their role in sexual dimorphism |
| title_fullStr | Functional analysis of B and C class floral organ genes in spinach demonstrates their role in sexual dimorphism |
| title_full_unstemmed | Functional analysis of B and C class floral organ genes in spinach demonstrates their role in sexual dimorphism |
| title_short | Functional analysis of B and C class floral organ genes in spinach demonstrates their role in sexual dimorphism |
| title_sort | functional analysis of b and c class floral organ genes in spinach demonstrates their role in sexual dimorphism |
| url | http://www.biomedcentral.com/1471-2229/10/46 |
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