Evidence for Autoploidy in Apomictic Paspalum Rufum

Quarín, Camilo Luis; Norrmann, Guillermo Alberto; Espinoza, Francisco

doi:10.1111/j.1601-5223.1998.00119.x

Cited by 30 publications

(26 citation statements)

References 14 publications

(4 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Rare diploid apomicts have been reported (reviewed by Savidan, 2000;Bicknell & Koltunow, 2004). An analysis of induced autotetraploids Paspalum hexastachyum (Quarin & Hanna, 1980), P. notatum (Quarin et al, 2001), and P. rufum (Quarin et al, 1998) indicated changes in the structure of the embryo sac, from the Polygonum to the Panicum type and, consequently, a possible change in the reproductive mode after chromosome doubling. Studies of induced tetraploid Paspalum suggested that genetic factors related to apomixis were present in the diploid genotype although expressed only at the tetraploid level.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

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

et al. 2005

View full text Add to dashboard Cite

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.

show abstract

Section: Discussionmentioning

confidence: 99%

“…This was suggested for P. rufum based on a cytogenetic analysis of triploid and tetraploid hybrids and of induced tetraploids (Quarin et al, 1998). Genetic analyses using molecular markers will be conducted to verify the origin of the tetraploid genome in B. brizantha.…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2005

View full text Add to dashboard Cite

show abstract

“…Quarín (1992) has proposed that at least in apomictic Panicoid grasses, polyploidy is a condition for apomixis and that apomixis is associated with autoploidy rather than alloploidy. Evidence for autoploidy was provided by Quarín et al (1998) in a tetraploid accession of P. rufum Ness. It has been hypothesized that hexaploid accessions are produced by hybridization (Katayama and Ikeda, 1975) or the fertilization of unreduced eggs in apomictic tetraploid forms (Quarín and Burson, 1991).…”

Section: Resultsmentioning

confidence: 99%

Chromosome numbers and meiotic behavior of some Paspalum accessions

et al. 2005

View full text Add to dashboard Cite

Chromosome number and meiotic behavior were evaluated in 36 Brazilian accessions of the grass Paspalum (which had never previously been analyzed) to determinate which accessions might be useful in interspecific hybridizations. The analysis showed that one accession of Paspalum coryphaeum was diploid (2n = 2x = 20) and one accession of Paspalum conspersum hexaploid (2n = 6x = 60), the remaining 34 accessions being tetraploid (2n = 4x = 40). The pairing configuration was typical for the ploidy level i.e. in the diploid, chromosomes paired as 10 bivalents, in tetraploids as bi-, tri-and quadrivalents, and in hexaploid as 30 bivalents. A low frequency of meiotic abnormalities (less than 10%) was observed in the diploid, hexaploid and some tetraploid accessions, although the majority of tetraploid accessions showed a high frequency of meiotic irregularities. The use of accessions with a low frequency of meiotic abnormalities in breeding programs is discussed.

show abstract

“…According to de Wet and Stalker (1974) the principal adaptative advantage of apomixis is that it can restore fertility in sexually sterile individuals. However, in the Panicoid grasses, apomixis has been also associated with autoploidy (Quarin 1992;Quarin et al 1998).…”

Section: Introductionmentioning

confidence: 98%

Genetic and embryological evidences of apomixis at the diploid level in Paspalum rufum support recurrent auto-polyploidization in the species

et al. 2008

View full text Add to dashboard Cite

Gametophytic apomixis is an asexual mode of reproduction by seeds. This trait is present in several plant families and is strongly associated with polyploidy. Paspalum rufum is a forage grass with sexual self-incompatible diploids (2n = 2x = 20) and aposporous-apomictic pseudogamous tetraploids (2n = 4x = 40). In previous work embryological observations of the diploid genotype Q3754 showed 8.8-26.8% of the ovaries having one meiotic plus an aposporous-like embryo sac, suggesting some capability for apomictic reproduction. The objective of this work was to characterize progenies derived from Q3754 to determine if aposporous sacs were functional and generated progenies via apomixis at the diploid level. Re-examination of Q3754 ovaries showed that 12.5% of them contained one sexual plus an aposporous sac confirming previous results. Progeny tests were carried out on two experimental families (H 1 and S 1 ) employing heterozygous RAPD marker loci. Family H 1 was obtained crossing Q3754 with a natural diploid genotype (Q3861) and S 1 derived from the induced self-pollination of Q3754. Genetic analysis of H 1 showed that all individuals derived from sexual reproduction. However, 5 out of 95 plants from S 1 showed the same heterozygous state as the mother plant for 14 RAPD loci suggesting a clonal origin. Further experiments, designed to test the functionality of aposporous sacs by flow cytometric analyses, were carried out on a third family (M 1 ) obtained by crossing Q3754 with the tetraploid plant Q3785. Histograms of 20 M 1 plants showed 15 diploids (75%), 4 triploids (20%) and 1 tetraploid (5%). Triploids and the tetraploid may have originated from functional aposporous embryo sacs. Likewise, the reconstruction of the developmental route of 40 individual seeds demonstrated that 11 of them (27.5%) derived from fertilized aposporic sacs. The results presented in this work indicate that gametophytic apomixis is effectively expressed at the diploid level in Paspalum rufum and could be the foundation of a recurrent auto-polyploidization process in the species.

show abstract

Evidence for Autoploidy in Apomictic Paspalum Rufum

Cited by 30 publications

References 14 publications

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

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

Chromosome numbers and meiotic behavior of some Paspalum accessions

Genetic and embryological evidences of apomixis at the diploid level in Paspalum rufum support recurrent auto-polyploidization in the species

Contact Info

Product

Resources

About