Pathways to Microspore Embryogenesis

Aionesei, Tatiana; Touraev, Alisher; Heberle‐Bors, Erwin

doi:10.1007/3-540-26889-8_2

Cited by 18 publications

(22 citation statements)

References 88 publications

(127 reference statements)

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“…As opposed to stress, hormones seem to be less critical for successful induction. According to Aionesei et al (2005), the relatively low importance of hormones in microspore embryogenesis relies on the fact that hormonal autotrophy is a condition sine qua non for true embryogenesis.…”

Section: Microspore/pollen Embryogenesismentioning

confidence: 99%

Androgenesis Revisited

Seguí-Simarro

2010

Bot. Rev.

103

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Androgenesis can be defined as the set of biological processes leading to an individual genetically coming exclusively from a male nucleus. Androgenesis was traditionally considered as the spontaneous, in vivo development of a male-derived haploid embryo from a fertilized egg where the female nucleus is eliminated. However, at present it is also possible to generate androgenic haploids/doubled haploids through in vitro microspore embryogenesis and by in vitro meiocyte-derived callogenesis. These three androgenic alternatives clearly differ in the inducible stage, but lead to the same final haploid or doubled haploid product. Whereas microspore embryogenesis is widely studied and applied, the other two routes are much less known. In this paper, the evidence accounting for the existence of these three alternative pathways is revised, as well as the mechanisms potentially involved in their induction. Their differences and similarities are discussed from a biological perspective, leading to the notion that they might represent an ancient survival mechanism triggered by similar factors. Resumen La androgénesis se define como el conjunto de vías biológicas que dan lugar a un individuo cuyo fondo genético proviene exclusivamente de un núcleo de origen masculino. Tradicionalmente, el concepto de androgénesis estaba restringido al desarrollo espontáneo, in vivo, de un embrión haploide o doble haploide a partir de una célula huevo fecundada en la que el material genético de origen femenino era inactivado o eliminado. Sin embargo, hoy en día sabemos que existen otras vías para conseguir haploides o doble haploides androgénicos, mediante embriogénesis de microsporas y mediante la formación de callos derivados de meiocitos. Estas tres alternativas androgénicas difieren claramente en la etapa en la que es posible la inducción, pero dan lugar al mismo producto haploide o doble haploide final. Mientras que la embriogénesis de microsporas es un fenómeno ampliamente estudiado y de clara aplicación práctica, las otras dos rutas son mucho menos conocidas. En este trabajo se revisan las evidencias existentes al respecto de estas tres alternativas androgén-icas, así como los mecanismos potencialmente implicados en su inducción. También se discuten sus diferencias y semejanzas, desde un punto de vista biológico, para llegar a la hipótesis de que estas rutas podrían representar un mecanismo atávico de supervivencia activado por factores similares.

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Section: Microspore/pollen Embryogenesismentioning

confidence: 99%

Androgenesis Revisited

Seguí-Simarro

2010

Bot. Rev.

103

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“…Since the cytoskeleton is clearly involved in the reprogramming of the microspore towards androgenesis (Touraev et al, 2001;Aionesei et al, 2005), it is reasonable to think that a cytoskeleton-affecting drug like colchicine may also have a role in androgenesis induction. It was proposed that colchicine-based MT depolymerization may release the microspore nuclei from their peripheral location, allowing for a central displacement which in turn permits a symmetric division (Zoriniants et al, 2005).…”

Section: C-mitosismentioning

confidence: 99%

Pathways to doubled haploidy: chromosome doubling during androgenesis

Seguí-Simarro

Nuez

2008

Cytogenet Genome Res

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Production of doubled haploid (DH) plants through androgenesis induction is a promising and convenient alternative to conventional selfing techniques for the generation of pure lines for breeding programs. This process comprises two main steps: induction of androgenesis and duplication of the haploid genome. Such duplication is sometimes indirectly induced by the treatments used to promote androgenic development. But usually, an additional step of direct chromosome doubling must be included in the protocol. Duplication of the haploid genome of androgenic individuals has been thought to occur through three mechanisms: endoreduplication, nuclear fusion and c-mitosis. In this review we will revise and analyze the evidences supporting each of the proposed mechanisms and their relevance during androgenesis induction, embryo/callus development and plant regeneration. Special attention will be devoted to nuclear fusion, whose evidences are accumulating in the last years.

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“…A large repository of data has been compiled concerning the early cellular and morphological changes that take place during the transition from male gametophyte to haploid embryo development in culture and commonalities among different species have been identified (for review, see Aionesei et al, 2005). The molecular mechanism underlying the induction of microspore embryogenesis is not known, although a number of studies have provided insight into this developmental process through the identification of genes and proteins that are differentially expressed during the transition from the gametophytic to embryonic cell state (Hosp et al, 2006).…”

mentioning

confidence: 99%

Combined Transcriptome and Proteome Analysis Identifies Pathways and Markers Associated with the Establishment of Rapeseed Microspore-Derived Embryo Development

et al. 2007

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Microspore-derived embryo (MDE) cultures are used as a model system to study plant cell totipotency and as an in vitro system to study embryo development. We characterized and compared the transcriptome and proteome of rapeseed (Brassica napus) MDEs from the few-celled stage to the globular/heart stage using two MDE culture systems: conventional cultures in which MDEs initially develop as unorganized clusters that usually lack a suspensor, and a novel suspensor-bearing embryo culture system in which the embryo proper originates from the distal cell of a suspensor-like structure and undergoes the same ordered cell divisions as the zygotic embryo. Improved histodifferentiation of suspensor-bearing MDEs suggests a new role for the suspensor in driving embryo cell identity and patterning. An MDE culture cDNA array and two-dimensional gel electrophoresis and protein sequencing were used to compile global and specific expression profiles for the two types of MDE cultures. Analysis of the identities of 220 candidate embryo markers, as well as the identities of 32 sequenced embryo up-regulated protein spots, indicate general roles for protein synthesis, glycolysis, and ascorbate metabolism in the establishment of MDE development. A collection of 135 robust markers for the transition to MDE development was identified, a number of which may be coregulated at the gene and protein expression level. Comparison of the expression profiles of preglobular-stage conventional MDEs and suspensor-bearing MDEs identified genes whose differential expression may reflect improved histodifferentiation of suspensor-bearing embryos. This collection of early embryo-expressed genes and proteins serves as a starting point for future marker development and gene function studies aimed at understanding the molecular regulation of cell totipotency and early embryo development in plants.Microspore embryogenesis describes the process in which the immature male gametophyte is induced to form a haploid embryo in vitro. Microspore embryo culture is a valuable tool for plant breeders because the haploid embryos that are produced (microspore-derived embryos [MDEs]) can be converted to homozygous doubled haploids using chromosome-doubling agents.The ability to obtain a homozygous population of plants in a single generation not only significantly reduces the time needed to develop inbred lines, but also facilitates selection for recessive and polygenic traits and speeds up the development of mapping populations and molecular markers for marker-assisted breeding (Forster and Thomas, 2005). Microspore embryogenesis has been described for more than 250 plant species and efficient protocols are available for about 20 of these (Maluszinsky et al., 2003). As with other regeneration processes, many species still remain recalcitrant for microspore embryogenesis and, even within a successful species, there are usually recalcitrant genotypes. There is, therefore, considerable interest in identifying the molecular genetic factors that define and control this process...

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Pathways to Microspore Embryogenesis

Cited by 18 publications

References 88 publications

Androgenesis Revisited

Androgenesis Revisited

Pathways to doubled haploidy: chromosome doubling during androgenesis

Combined Transcriptome and Proteome Analysis Identifies Pathways and Markers Associated with the Establishment of Rapeseed Microspore-Derived Embryo Development

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