Beyond promiscuity: From sexuality to apomixis in flowering plants

Estrada-Luna, Andrés Adolfo; Huanca‐Mamani, Wilson; Acosta-García, Gerardo; León-Martínez, Gloria; Becerra-Flora, Alicia; Pérez-Ruíz, Rigoberto V.; Vielle‐Calzada, Jean‐Philippe

doi:10.1079/ivp2001278

Cited by 9 publications

(9 citation statements)

References 46 publications

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“…Despite their importance in this type of breeding scheme, only a limited number of studies have described female reproductive development in a few of the more than 150 tuber-bearing Solanum species. We have successfully identified diploid (2n=2x=24) self-compatible genotypes in a population of S. cardiophyllum native of central Mexico (Estrada-Luna et al 2002). Our observations indicate that, in this species, megasporogenesis and megagametogenesis give rise to a female gametophyte of the Polygonum type by cellular mechanisms resembling those that have been described for -Leonard 1935;Arnason 1948) and S. demissum (Walker 1955).…”

Section: Discussionsupporting

confidence: 63%

“…The establishment of insertional mutagenesis and gene trapping approaches in these genetic backgrounds will dramatically simplify the identification of genes important for embryo and endosperm development (Estrada-Luna et al 2002). These new approaches, combined with the use of meiotic mutants to solve genetic problems associated with 2n-gamete formation, promise to accelerate progress in the understanding and establishment of true potato seed as a more efficient strategy for potato production.…”

Section: Discussionmentioning

confidence: 99%

“…To explore the potential use of S. cardiophyllum as a model system for studying the developmental biology of female gametophyte development and seed formation, we collected a wide range of its naturally grown variants and identified several diploid genotypes (2n=2x=24) that form viable seeds after self-pollination (Estrada-Luna et al 2002). In this paper we report the reproductive characterization of sexual diploid self-compatible genotypes of S. cardiophyllum suitable for genetic studies.…”

Section: Introductionmentioning

confidence: 99%

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Female reproductive development and pollen tube growth in diploid genotypes of Solanum cardiophyllum Lindl.

2004

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We have characterized female gametophyte (megagametophyte) development and the kinetics of pollen tube growth in self-pollinated diploid genotypes (2n=2x=24) of Solanum cardiophyllum Lindl. that show normal seed formation. In this species megasporogenesis and megagametogenesis give rise to a female gametophyte of the Polygonum type composed of two synergids, an egg cell, a binucleated central cell and three antipodals; however, asynchronous abnormalities resembling mechanisms that prevail during the formation of second division restitution gametes were observed. In self-pollinated pistils at least 1-2% of germinating pollen tubes were able to reach the megagametophyte 60-84 hours after pollination (hap). Although the egg cell acquired a zygote-like morphology 60-84 hap, division of the primary endosperm nucleus was only observed 84 hap. The analysis of genetic variability in full-sib progeny confirmed that seeds are derived from sexual reproduction. These observations suggest that diploid genotypes of S. cardiophyllum can serve as an ideal system to genetically investigate true seed formation in a tuber-bearing Solanum species.

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Section: Discussionsupporting

confidence: 63%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Female reproductive development and pollen tube growth in diploid genotypes of Solanum cardiophyllum Lindl.

2004

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“…The first evidence of in vivo adventitious embryony is generally observed during early female gametophyte formation (Estrada-Luna et al 2002). In a similar vein, morphogenic events have occurred in vitro for explants excised at approximately the time that these explants formed meiocytes.…”

Section: Apomixismentioning

confidence: 91%

“…In the latter case, the megaspore mother cell enters meiosis, but this process is terminated in the zygotene stage before chromosome reduction occurs (Estrada-Luna et al 2002). In a few tree species, many embryos are produced by apomixis.…”

Section: Apomixismentioning

confidence: 98%

Recalcitrance in clonal propagation, in particular of conifers

Bonga

Klimaszewska

Aderkas

2009

Plant Cell Tiss Organ Cult

170

134

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Despite major advances in forest biotechnology, clonal regeneration by somatic embryogenesis or organogenesis is still difficult for many woody species and is often limited to the use of juvenile explants. Adventitious regeneration of plants from gymnosperms older than zygotic embryos, and frequently even from highly immature zygotic embryos, is often difficult or has not yet been achieved. A number of experimental approaches that could eventually lead to overcoming recalcitrance are suggested in this review. When cloning trees of various ages, it is important to determine first which part of the individual contains the most responsive cells and at what time of the year these cells are in the most responsive state. This allows selection of the most useful explants. In hardwood trees and a few gymnosperms, responsive tissues are found in root or stump sprouts and in tissues near the site of meiosis at about the time that meiosis takes place. Another potentially active area is the shoot apex with most or all of its leaf or needle primordia removed. Apomixis is a natural form of clonal regeneration but occurs naturally in only one gymnosperm species. As the genetic mechanism of apomixis has been in part elucidated, the induction of apomixis by experimental means may soon be possible. The cytoplasm plays a major role in the expression or repression of nuclear genes that control embryogenesis. Expression of nuclear genes can be manipulated by nuclear transfer into de-nucleated cells (e.g., the cytoplasm of egg cells). Cytoplasmic control also plays a role in regeneration by androgenesis, asymmetric cell division and cell isolation. A short overview is presented of the genetic mechanisms involved in embryo initiation, maturation and germination and how manipulation of these mechanisms by genetic transformation could help in overcoming recalcitrance. It is expected that rapid development in the fields of research areas discussed in this review will over time eliminate the problem of recalcitrance in many instances where it is currently prevalent.

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Challenges and Limitations to the Use of Haploidy in Crop Improvement

Palmer

Keller

Haploids in Crop Improvement II

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There have been a number of recent reviews on the uses of doubled haploids in plant improvement (Kao 1996; Kush and Virmani 1996;Pelletier 1998;Bohanec 2002). Consequently this chapter will concentrate on the limitations and potentials of haploids and doubled haploids in plant improvement while emphasizing the recent literature. There is an impressive list of plant species in which haploids and doubled haploids have been produced (Maluszynski et al. 1996(Maluszynski et al. , 2003. However, most of the published protocols are developed by genotype selection, manipulation of donor plant growth conditions and modifications to culture media composition and culture conditions.There have been attempts at understanding the fundamental basis for gametophyte to sporophyte transition and morphogenesis, but our knowledge of how the process is regulated is still fragmentary (Kyo et al. 2003). What are the signals, genes and gene products involved in this process? For this technology to be widely used in crop improvement, greater insight into the molecular and biochemical basis for induction of gametophyte embryogenesis must be achieved.There are a number of emerging crop species of medicinal, herbal and neutraceutical value where genetic improvement would benefit from doubled haploid technology. While an empirical approach to haploidy is still useful, a fundamental understanding of the process would be invaluable for the development of genotypes with reliable and diverse characteristics.Significant advances have been made in the use of doubled haploids in the improvement of some species, e.g. members of the Brassicaceae, Poaceae and Solanaceae. However, there has been little improvement in the recovery of doubled haploids from members of the Fabaceae. Soybean, Glycine max (L.) Merr.; in spite of its commercial importance, anther culture remains the only route to haploidy (Hu et al. 1996;Rodrigues et al. 2004). In all cases, haploids are produced at a frequency too low to be of value in a soybean breeding program.

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Beyond promiscuity: From sexuality to apomixis in flowering plants

Cited by 9 publications

References 46 publications

Female reproductive development and pollen tube growth in diploid genotypes of Solanum cardiophyllum Lindl.

Female reproductive development and pollen tube growth in diploid genotypes of Solanum cardiophyllum Lindl.

Recalcitrance in clonal propagation, in particular of conifers

Challenges and Limitations to the Use of Haploidy in Crop Improvement

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