Sexual diploid and apomictic tetraploid races in Thrasya petrosa (Gramineae)
Carlos A. Acuña A , Eric J. Martínez A and Camilo L. Quarin A BA Instituto de Botánica del Nordeste (IBONE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste (UNNE), Corrientes, Argentina.
B Corresponding author. Present address: Instituto de Botánica del Nordeste, Casilla de Correo 209, 3400 Corrientes, Argentina. Email: quarin@agr.unne.edu.ar
Australian Journal of Botany 53(5) 479-484 https://doi.org/10.1071/BT04190
Submitted: 19 November 2004 Accepted: 6 April 2005 Published: 11 August 2005
Abstract
Thrasya petrosa (Trin.) Chase is the most widespread species of a grass genus indigenous to the New World. Genetic systems in diploid (2n = 2x = 20) and tetraploid (2n = 4x = 40) races of T. petrosa were investigated. The diploid race exhibited embryological development typical of sexual reproduction, but failed to produce seed because of self-incompatibility, whereas the tetraploid showed embryological pathways characteristic of facultative apomixis. Consequently, some ovules showed a normal meiotic embryo sac, others had one to several aposporous sacs, and, finally, some ovules had one or more aposporous sacs beside the meiotic one. A uniform progeny test assisted by molecular markers confirmed that the main reproductive mode for the tetraploid race was apomixis, despite some sexual reproductive structures observed by cytoembryological analyses. The chromosome pairing patterns at meiosis suggested that autoploidy was the genetic origin of the tetraploid races of T. petrosa. In addition, the close relationship between Thrasya Kunth and Paspalum L. previously supported by phylogenetic analyses is further sustained by the particular genetic system shared by the two genera. The system involves co-specific sexual self-incompatible diploids and apomictic, pseudogamous and self-compatible polyploids.
Acknowledgments
This study was financed by grants from Secretaría General de Ciencia y Técnica, UNNE, and Agencia Nacional de Promoción Científica y Tecnológica, Project PICT/99 No. 8-6134. Acuña was funded by a fellowship from CONICET and Secretaría General de Ciencia y Técnica, UNNE. Martínez and Quarin are members of the research staff of CONICET. Finally, we appreciate the friendly assistance concerning idiomatic English provided by Ann R. Soffes Blount, Assistant Professor, University of Florida.
Aliscioni SS
(2002) Phylogeny of the genus Paspalum (Poaceae: Panicoideae: Paniceae). Annals of the Missouri Botanical Garden 89, 504–523.
Bashaw EC, Holt EC
(1958) Megasporogenesis, embryo sac development and embryogenesis in dallisgrass, Paspalum dilatatum Poir. Agronomy Journal 50, 753–756.
Bashaw EC
(1962) Apomixis and sexuality in buffelgrass. Crop Science 2, 412–415.
Bashaw EC, Hovin AW, Holt EC
(1970) Apomixis, its evolutionary significance and utilization in plant breeding. In ‘Proceedings of the 11th international grassland congress’. (Ed. MJT Norman )
pp. 245–248. (University of Queensland Press: Brisbane)
Burman AG
(1985) Revision of the genus Thrasya.
Acta Botanica Venezuelica 14, 7–93.
Davidse G, Pohl RW
(1974) Chromosome number, meiotic behavior, and notes on tropical American grasses (Gramineae). Canadian Journal of Botany 52, 317–328.
Forbes I, Burton GW
(1961) Cytology of diploids, natural and induced tetraploids, and intraspecies hybrids of bahiagrass, Paspalum notatum Flügge. Crop Science 1, 402–406.
Giussani LM,
Cota-Sánchez JH,
Zuloaga FO, Kellog E
(2001) A molecular phylogeny of the grass subfamily Panicoideae (Poaceae) shows multiple origins of C4 photosynthesis. American Journal of Botany 88, 1993–2012.
Hayman DL
(1956) Cytological evidence of apomixis in Australian Paspalum dilatatum.
Journal of the Australian Institute of Agricultural Science 22, 292–293.
Martínez EJ,
Hopp HE,
Stein J,
Ortiz JPA, Quarin CL
(2003) Genetic characterization of apospory in tetraploid Paspalum notatum based on the identification of linked molecular markers. Molecular Breeding 12, 319–327.
| Crossref | GoogleScholarGoogle Scholar |
Nicora, E ,
and
Rúgolo de Agrasar, Z (1987).
Norrmann GA,
Quarin CL, Burson BL
(1989) Cytogenetics and reproductive behaviour of different chromosome races in six Paspalum species. Journal of Heredity 80, 24–28.
Norrmann GA,
Quarin CL, Killeen TJ
(1994) Chromosome numbers in Bolivian grasses (Gramineae). Annals of the Missouri Botanical Garden 81, 768–774.
Pohl RW, Davidse G
(1971) Chromosome numbers of Costa Rican grasses. Brittonia 23, 293–324.
Pupilli F,
Cáceres ME,
Quarin CL, Arcioni S
(1997) Segregation analysis of RFLP markers reveals a tetrasomic inheritance in apomictic Paspalum simplex.
Genome 40, 822–828.
Quarin CL
(1992) The nature of apomixis and its origin in Panicoids grasses. Apomixis Newsletter 1, 8–15.
Quarin CL,
Burson BL, Burton GW
(1984) Cytology of intra and interspecific hybrids between two cytotypes of Paspalum notatum and P. cromyorrhizon.
Botanical Gazette 145, 420–426.
| Crossref | GoogleScholarGoogle Scholar |
Quarin CL,
Norrmann GA, Espinoza F
(1998) Evidence for autoploidy in apomictic Paspalum rufum.
Hereditas 129, 119–124.
| Crossref | GoogleScholarGoogle Scholar |
Stein J,
Quarin CL,
Martínez EJ,
Pessino SC, Ortiz JPA
(2004) Tetraploid races of Paspalum notatum show polysomic inheritance and preferential chromosome pairing around the apospory-controlling locus. Theoretical and Applied Genetics 109, 186–191.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
