Apomixis: Genetics and Breeding

Savidan, Yves

doi:10.1002/9780470650158.ch2

Cited by 84 publications

(112 citation statements)

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“…All tropical forage grasses studied are polyploid and reproduce through aposporous apomixis with pseudogamy (Miles et al 1996;Savidan 2000) but sexual genotypes have been identified in the germplasm collections (Nakajima et al 1979;Jungmann et al 2009a).…”

Section: Introductionmentioning

confidence: 99%

Molecular genetic variability, population structure and mating system in tropical forages

Garcia

Vigna

Sousa

et al. 2013

Trop Grass - Forr Trop

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Microsatellite (SSR) markers were developed for the following tropical forage species, using accessions available from the plant genetic resources (PGR) collections held by EMBRAPA (Brazilian Agricultural Research Corporation): Brachiaria brizantha, B. humidicola, Panicum maximum, Paspalum spp., Stylosanthes capitata, S. guianensis, S. macrocephala, Calopogonium mucunoides and Centrosema spp. The markers were used to analyze population structure and genetic diversity, evolution and origin of the genetic variability in the center of origin, mating systems and genetic resources in EMBRAPA's germplasm bank. The results shed light on the amount of genetic variation within and between populations, revealed the need in some cases for further plant collection to adequately represent the species in PGR collections, allowed us to assemble core collections (subsets of the total collections) that should contain most of the available diversity and (in the case of the legumes) showed the need to avoid unwanted outcrossing when regenerating conserved material. The data will allow plant breeders to better select accessions for hybrid production, discriminate between genotypes and use marker-assisted selection in breeding programs. Our results will also underpin the construction of genetic maps, mapping of genes of agronomic interest and numerous other studies on genetic variability, population structure, gene flow and reproductive systems for the tropical forage species studied in this work. ResumenSe desarrollaron marcadores microsatélite (SSR) para las siguientes especies forrajeras tropicales, usando accesiones de germoplasma disponibles en las colecciones de recursos genéticos mantenidas por EMBRAPA (Empresa Brasileira capitata, S. guianensis, S. macrocephala, Calopogonium mucunoides y Centrosema spp. Los marcadores se usaron para analizar la estructura de las poblaciones y su diversidad genética; la evolución y el origen de la variabilidad gené-tica en los respectivos centros de origen; los sistemas reproductivos; y los recursos genéticos en el banco de germoplasma de EMBRAPA. Los resultados arrojaron luz sobre la magnitud de la variación genética dentro de y entre poblaciones; revelaron la necesidad, para algunas especies, de incrementar las colecciones de germoplasma y así obtener una adecuada representación de las especies en las colecciones de recursos genéticos; permitieron establecer colecciones núcleo (subconjuntos de colecciones grandes), representativas de la diversidad genética disponible en las respectivas colecciones completas; y mostró, para las leguminosas, el riesgo de cruzamientos no deseados al multiplicar semilla de las accesiones conservadas. La información obtenida facilitará a los fitomejoradores la selección de accesiones para la generación de híbridos, la distinción entre genotipos, y el uso de la selección asistida por marcadores en programas de fitomejoramiento. Los resultados también ayudarán para la construcción de mapas genéticos, el mapeo de genes de interés agronómico y otros estudios...

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Section: Introductionmentioning

confidence: 99%

Molecular genetic variability, population structure and mating system in tropical forages

Garcia

Vigna

Sousa

et al. 2013

Trop Grass - Forr Trop

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“…The ability to produce genetically identical progeny via seed is of significant value to agriculture for its power to fix complex favorable genotypes, including the higher yields often found in F 1 hybrids. Apomixis is documented in more than 120 angiosperm genera (Carman 1997); however, no major seed crop species are apomictic, and attempts to introduce the apomixis trait to crops from apomictic relatives by crosspollination have been largely unsuccessful (Savidan 2000). Apomixis is also of interest from developmental and evolutionary perspectives.…”

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confidence: 99%

The Genetic Control of Apomixis: Asexual Seed Formation

2014

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Apomixis (asexual seed formation) is the result of a plant gaining the ability to bypass the most fundamental aspects of sexual reproduction: meiosis and fertilization. Without the need for male fertilization, the resulting seed germinates a plant that develops as a maternal clone. This dramatic shift in reproductive process has been documented in many flowering plant species, although no major seed crops have been shown to be capable of apomixis. The ability to generate maternal clones and therefore rapidly fix desirable genotypes in crop species could accelerate agricultural breeding strategies. The potential of apomixis as a nextgeneration breeding technology has contributed to increasing interest in the mechanisms controlling apomixis. In this review, we discuss the progress made toward understanding the genetic and molecular control of apomixis. Research is currently focused on two fronts. One aims to identify and characterize genes causing apomixis in apomictic species that have been developed as model species. The other aims to engineer or switch the sexual seed formation pathway in non-apomictic species, to one that mimics apomixis. Here we describe the major apomictic mechanisms and update knowledge concerning the loci that control them, in addition to presenting candidate genes that may be used as tools for switching the sexual pathway to an apomictic mode of reproduction in crops.

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“…Apomictic forage grasses display wide variation in nature, however, little of this diversity has been sampled (Savidan 2000). The first species intensively collected was P. maximum in East Africa by the French Institute of Research for Development (Former ORSTOM -Office de la Recherche Scientifique et Technique d'Outre-Mer) (Combes and Pernès 1970), and later by the Japanese Hojito and Horibata (1982).…”

Section: Reproductive Behaviormentioning

confidence: 99%