Sexual and asexual (apomictic) seed development in flowering plants: molecular, morphological and evolutionary relationships

Tucker, Matthew R.; Koltunow, Anna M.

doi:10.1071/fp09078

Cited by 70 publications

(73 citation statements)

References 121 publications

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“…A cultivar Marandu foi liberada pela Embrapa em 1983, para atender a demanda por cultivares resistentes à cigarrinha-das-pastagens, e é hoje o capim mais plantado no Brasil (Araújo et al, 2008). A progênie resultante da reprodução apomítica é constituída por clones idênticos à planta-mãe (Ozias-Akins, 2006;Tucker & Koltunow, 2009), o que implica baixa diversidade genética. As únicas fontes de diversidade dessa população apomítica facultativa são mutações somáticas ou ocorrência de fecundação nos sacos embrionários do tipo Polygonum, característicos de plantas sexuais.…”

Section: Introductionunclassified

Histologia da embriogênese somática induzida em embriões de sementes maduras de Urochloa brizantha apomítica

Lenis-Manzano

Araújo

Valle

et al. 2010

Pesq. agropec. bras.

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Resumo -O objetivo deste trabalho foi descrever o processo de embriogênese somática em Urochloa brizantha cv. Marandu (Syn. Brachiaria brizantha cv. Marandu) e fornecer subsídios para o aprimoramento dos métodos de cultura de tecidos e transformação genética. Calos embriogênicos foram obtidos por indução em embriões isolados de sementes maduras, e cultivados in vitro, em meio de cultura que continha ácido 2,4-diclorofenoxiacético, 6-benzilaminopurina e caseína hidrolisada. Plântulas foram regeneradas a partir dos calos embriogênicos, na presença de ácido naftalenoacético e cinetina. Esse processo foi descrito morfologicamente por observações em microscopia de luz de secções seriadas semifinas de tecidos fixados, ao longo do processo de regeneração, em FAA [formaldeído (40%): ácido acético glacial: etanol (50%), a 5:5:90 v/v/v]. Os embriões das sementes de U. brizantha cv. Marandu não têm epiblasto e são classificados como do tipo panicoide. Nas condições estabelecidas de cultura in vitro, calos embriogênicos e embriões somáticos de U. brizantha cv. Marandu, desenvolvem-se a partir de células meristemáticas do escutelo.Termos para indexação: Brachiaria, cultura de tecidos, melhoramento de forrageiras, regeneração, transformação genética. Histology of somatic embryogenesis induced in embryos of mature seeds of the apomictic Urochloa brizanthaAbstract -The objective of this work was to describe the process of somatic embryogenesis in Urochloa brizantha cv. Marandu (Syn. Brachiaria brizantha cv. Marandu) and to provide support for the improvement of tissue culture and genetic transformation methods. Embryogenic calli were obtained by induction in embryos isolated from mature seeds, and cultivated in vitro in culture medium containing 2,4-dichlorophenoxyacetic acid, 6-benzylaminopurine and hydrolyzed casein. Plantlets were regenerated from the embryogenic calli in the presence of naphthaleneacetic acid and kinetin. This process was described by morphological observations of serial semithin sections of tissues fixed along the regeneration process in FAA (40% formaldehyde: acetic acid: 50% ethanol, at 5:5:90 v/v/v), using light microscopy. Seed embryos of U. brizantha cv. Marandu do not have epiblast and are classified as Panicum-type. Under in vitro culture conditions, embryogenic calli and somatic embryos of U. brizantha cv. Marandu develop from meristematic cells of the scutellum.

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Section: Introductionunclassified

Histologia da embriogênese somática induzida em embriões de sementes maduras de Urochloa brizantha apomítica

Lenis-Manzano

Araújo

Valle

et al. 2010

Pesq. agropec. bras.

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“…The other reproductive strategy, devoid of meiosis (or meiosis is disturbed, depending on apomixis type) and fertilization of the egg cell, is apomixis, where the progeny are clones of the mother [2]. Molecular mechanism of apomixis has been investigated for many years, and several genes have been discovered that may contribute to the initiation of apomictic development.…”

Section: Autonomous Endospermmentioning

confidence: 99%

“…In fie-1/FIE heterozygote, advanced stages of AE development (AE3 and AE4) emerged with the greatest Tab. 2 The occurrence of four developmental stages of autonomous endosperm (AE) in unpollinated ovules of Arabidopsis thaliana on media with steroid hormones and on hormone-free medium (M1 -control). 1 No.…”

Section: The Development Of Ae In Different Treatmentsmentioning

confidence: 99%

Exogenous steroid hormones stimulate full development of autonomous endosperm in Arabidopsis thaliana

et al. 2015

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Most flowering plants, including important crops, require double fertilization to form an embryo and endosperm, which nourishes it. Independence from fertilization is a feature of apomictic plants that produce seeds, from which the plants that are clones of the mother plant arise. The phenomenon of apomixis occurs in some sexual plants under specific circumstances. Since the launch of a fertilization-independent mechanism is considered a useful tool for plant breeding, there have been efforts to artificially induce apomixis. We have been able to produce fertilization-independent endosperm in vitro in Arabidopsis over the last few years. This paper demonstrates the methods of improving the quality of the endosperm obtained using plant and mammalian steroid hormones. Additionally, it shows the study on the autonomous endosperm (AE) formation mechanism in vitro.This paper examines the effect of exogenous steroid hormones on unfertilized egg and central cell divisions in culture of unpollinated pistils of Arabidopsis Col-0 wild-type and fie-1 mutant. All media with hormones used (estrone, androsterone, progesterone, and epibrassinolide) stimulated central cell divisions and fertilization-independent endosperm development. The stages of AE development followed the pattern of Arabidopsis thaliana wild type after fertilization. Subsequent stages of AE were observed from 2-nuclear up to cellular with the most advanced occurring on medium with 24-epibrassinolide and progesterone. The significant influence of mammalian sex hormones on speed of AE development and differentiation was noticed. Using restriction analysis, the changes in methylation of FIE gene was established under in vitro condition. The authors of this paper showed that Arabidopsis thaliana has a high potency to fertilization-independent development.

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“…The only two reported insertional lines available did not show obvious defects during either vegetative or reproductive development and do not show differences in the levels of AGP18 expression compared with the wild type (SALK_117268, located at +820; and GT6565, at +871; Yang and Showalter, 2007). Although abnormal survival of meiotically derived megaspores has been reported for the Arabidopsis mutant antikevorkian at a presumed frequency of ;10% (Yang and Sundaresan, 2000;Tucker and Koltunow, 2009), its molecular function remains unknown. The variable number of differentiated megaspores found in ovules of AGP18 overexpressing lines suggests that AGP18 could play a role in mediating some of the signaling pathways involved in determining megaspore fate following meiosis.…”

Section: Discussionmentioning

confidence: 99%

The Classical Arabinogalactan Protein AGP18 Mediates Megaspore Selection inArabidopsis

Demesa-Arévalo

Vielle‐Calzada

2013

The Plant Cell

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Female gametogenesis in most flowering plants depends on the predetermined selection of a single meiotically derived cell, as the three other megaspores die without further division or differentiation. Although in Arabidopsis thaliana the formation of the functional megaspore (FM) is crucial for the establishment of the gametophytic generation, the mechanisms that determine the specification and fate of haploid cells remain unknown. Here, we show that the classical arabinogalactan protein 18 (AGP18) exerts an active regulation over the selection and survival of megaspores in Arabidopsis. During meiosis, AGP18 is expressed in integumentary cells located in the abaxial region of the ovule. Overexpression of AGP18 results in the abnormal maintenance of surviving megaspores that can acquire a FM identity but is not sufficient to induce FM differentiation before meiosis, indicating that AGP18 positively promotes the selection of viable megaspores. We also show that all four meiotically derived cells in the ovule of Arabidopsis are competent to differentiate into a gametic precursor and that the function of AGP18 is important for their selection and viability. Our results suggest an evolutionary role for arabinogalactan proteins in the acquisition of monospory and the developmental plasticity that is intrinsic to sexual reproduction in flowering plants.

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Sexual and asexual (apomictic) seed development in flowering plants: molecular, morphological and evolutionary relationships

Cited by 70 publications

References 121 publications

Histologia da embriogênese somática induzida em embriões de sementes maduras de Urochloa brizantha apomítica

Histologia da embriogênese somática induzida em embriões de sementes maduras de Urochloa brizantha apomítica

Exogenous steroid hormones stimulate full development of autonomous endosperm in Arabidopsis thaliana

The Classical Arabinogalactan Protein AGP18 Mediates Megaspore Selection inArabidopsis

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