Chromosome doubling in <i>Tripsacum</i>: the production of artificial, sexual tetraploid plants

Leblanc, Olivier; Dueñas, Montserrat; Hernández, Martha; Bello, S.; García, Valéria Augusta; Berthaud, Julien; Savidan, Yves

doi:10.1111/j.1439-0523.1995.tb00798.x

Cited by 19 publications

(17 citation statements)

References 12 publications

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“…Similar type of inheritance was reported in other aposporous apomictic grasses such as Pennisetum (Sherwood et al, 1994) and Panicum (Savidan, 1982), diplosporous such as Eragrostis curvula (Voigt & Burson, 1981) and Tripsacum dactyloides (Leblanc et al, 1995) and in dicotyledonous genera such as Ranunculus (Nogler, 1984) and Hieracium (Bicknell et al, 2000). An association of apomixis with polyploidy is evident (Carman, 1997), although the apomictic mode of reproduction is not exclusive of polyploids.…”

Section: Discussionmentioning

confidence: 60%

Evidence of sexuality in induced tetraploids of Brachiaria brizantha (Poaceae)

et al. 2005

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Difficulties in obtaining new breeding lines of Brachiaria (Trin.) Griseb., an important forage grass in Brazil, are mostly related to differences in ploidy among the accessions, and to apomixis, an asexual mode of reproduction. Usually, sexual accessions are diploid while apomicts are polyploid. Induced tetraploids of Brachiaria brizantha (A. Rich.) Stapf have been successfully obtained and this paper presents the results of a study of their reproductive modes and fertility. Despite frequent meiotic aberrations during microspore development, the induced tetraploids produced viable pollen and produced progeny after controlled self-pollination. Similarly to the original diploid sexual progenitor, embryo sacs of the Polygonum type with confirmed meiotic origin were present in the induced tetraploids suggesting chromosome doubling did not alter the reproductive mode. The embryo sac of the Polygonum type was also observed in progenies obtained after self and open pollination. Nevertheless, embryo sacs of the Polygonum and the Panicum types within the same ovule were observed in some progenies obtained after open pollination, probably having resulted from hybridization with tetraploid, apomictic plants. Indeed, the compatibility of the progeny with tetraploid, apomictic B. brizantha was confirmed by the formation of mature caryopses after controlled pollination. Evidence is presented that the induced tetraploids and their progeny are sexual plants and that they are compatible with natural tetraploid B. brizantha. The induced tetraploids will be useful for analyses of apomictic inheritance as well as in the development of sexual tetraploid lines in Brachiaria breeding programs.

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Section: Discussionmentioning

confidence: 60%

Evidence of sexuality in induced tetraploids of Brachiaria brizantha (Poaceae)

et al. 2005

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“…The ploidy level of colchicine-treated calluses was estimated by flow cytometry according to the protocol described by Leblanc et al (1995). Plants were regenerated from 4× callus sectors following the method described by Bovo and Mroginski (1986).…”

Section: Flow Cytometry and Plant Regenerationmentioning

confidence: 99%

A rise of ploidy level induces the expression of apomixis in Paspalum notatum

Quarín¹,

Espinoza²,

Martínez³

et al. 2001

Sexual Plant Reproduction

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140

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The common races of bahiagrass, Paspalum notatum, are tetraploid (2n=4x=40) and reproduce by aposporous apomixis. Paspalum notatum var. saurae is the corresponding diploid (2n=2x=20) sexual race that outbreeds due to self-incompatibility. Chromosome doubling was induced by colchicine treatments in three individual plants from a natural diploid population. Embryological studies demonstrated that one of the induced autotetraploid plants reproduced sexually. The other two autotetraploids were facultative apomicts. These results indicate that an unexpressed gene(s) for apomixis exists at the diploid level. The expression of the trait is ploidydependent. The ploidy dependency may act either on the locus controlling apomixis through some transcription factors or via a secondary locus which requires a higher allele dosage to affect the expression of the main locus.

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“…Interestingly, all artificially produced tetraploids studied to date have been sexual (Leblanc et al 1995a;Salon and Earle 1998). Diplosporous apomixis in Tripsacum is characterized by five anomalies: abortion of meiosis in the megaspore mother cell (MMC) during prophase, precocious maturation of the MMC into a functional megaspore (FM), precocious formation of an unreduced embryo sac (ES) from the unreduced FM, parthenogenic embryo development from the unreduced egg, which often forms before stigma receptivity, and pseudogamous endosperm formation, which requires central cell fertilization and causes the maternal to paternal endosperm genome ratio to differ from that of sexual plants (Grimanelli et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Heterochronic features of the female germline among several sexual diploid Tripsacum L. (Andropogoneae, Poaceae)

et al. 2006

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One element of gametophytic apomixis is unreduced embryo sac (ES) formation, which often occurs precociously displacing or replacing meiosis and causing apospory or diplospory, respectively. This study evaluated a premise that apomixis may evolve in hybridogenous plants that contain duplicate sets of allelically divergent ovule development heterochrony genes. The duplicate sets of genes would belong to duplicate genomic regions that are recombinationally isolated from each other (no gene flow) by allopolyploidy or paleopolyploidy, and this isolation would genetically stabilize apomixis. For apomixis to evolve, the ancestral donors of the duplicate regions must have differed from each other in timing of megasporogenesis, ES formation and embryony such that epigenetic misexpressions, or competitions in expression, of the duplicate heterochrony genes in hybridogenous derivatives would cause apomixis. Herein, we report substantial heterochrony in onset timing of germline stages among several sexual diploid Tripsacum genotypes, which may have been progenitors of apomictic polyploid Tripsacum. Tripsacum floridanum and Tripsacum zopilotense genotypes entered meiosis early. The former advanced rapidly through ES formation, but the latter entered a lengthy lag phase prior to ES formation. In two Tripsacum dactyloides var. dactyloides genotypes, meiosis occurred late and was followed by a distinct lag phase prior to ES formation. Likewise, the T. dactyloides var. meridonale genotype entered meiosis late, but the lag phase was brief. These differences appear to reflect allelic diversity at loci responsible for onset timing of different germline development stages within and across species and possibly across the recombinationally isolated duplicate chromosome regions in the Tripsacum paleopolyploid haplome (x = 18). Unique combinations of divergent alleles in hybridogenous plants coupled with polyploidy induced gene misexpressions may be required for apomixis to evolve.

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Chromosome doubling in Tripsacum: the production of artificial, sexual tetraploid plants

Cited by 19 publications

References 12 publications

Evidence of sexuality in induced tetraploids of Brachiaria brizantha (Poaceae)

Evidence of sexuality in induced tetraploids of Brachiaria brizantha (Poaceae)

A rise of ploidy level induces the expression of apomixis in Paspalum notatum

Heterochronic features of the female germline among several sexual diploid Tripsacum L. (Andropogoneae, Poaceae)

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