Cytoembryological evaluation, meiotic behavior and pollen viability of Paspalum notatum tetraploidized plants

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Paspalum notatum is a polymorphic species with two accepted varieties, according to the ploidy level. The ploidy level is closely related to the reproductive mode of this species. Usually, diploid cytotypes have sexual reproduction, and tetraploid cytotypes have an apomictic reproduction. Apomixis limits genetic recombination, hindering the development of new cultivars. The identification of sexual plants represents many possibilities in breeding programs. This study aimed to analyze the chromosome number in P. notatum accessions under agronomic evaluation. Ploidy level was determined in 25 accessions. Two ploidy levels were detected, resulting in 21 tetraploid and four diploid accessions. The four diploid accessions originate from Argentina and Uruguay, in a region close to the origin of Pensacola, which is a diploid sexual cultivar of P. notatum. These new diploid accessions may be useful in the development of breeding programs of Paspalum species.

Section: Resultsmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

New wild diploids in Paspalum notatum Flügge (Poaceae): potential accessions for use in breeding.

Fachinetto

Dall'Agnol

Schifino-Wittmann

et al. 2018

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“…Recent studies in native species of the state of Rio Grande do Sul show irregularities in meiotic behavior similar to that of crem, but with a predominance of regularity and high pollen viability in lemon grass (Elionurus muticus) (Füller et al 2015), cherry tree accessions (Eugenia involucrata) (Guerra et al 2016), and Paspalum notatum tetraploidized plants (Krycki et al 2016). According to Pagliarini (2000), irregular chromosome segregation is the most common meiotic abnormality in both cultivated and native species, being characterized by the presence of chromosomes in precocious chromosome ascension and laggard choromosome.…”

Section: Krb Tolomeotti Et Almentioning

confidence: 95%

Cytogenetic characterization of Tropaeolum pentaphyllum Lam

Tolomeotti

Felippi

Donazzolo

2018

The species Tropaeolum pentaphyllum Lam. (batata-crem or crem) is of great economic and medicinal importance. For being an endangered species, the knowledge of its genetic variability is necessary. Considering the lack of cytological studies on this species, this work describes the chromosome numbers, the meiotic behavior, the meiotic index, and the viability of the pollen grains of three populations of T. pentaphyllum from Rio Grande do Sul, Brazil. The three populations presented 2n = 28 chromosomes. Meiotic behavior was regular, with low abnormality frequency (<1%), which culminated in IMx> 90% in the three accessions. This meiotic stability resulted in high production of viable pollen grains, which will favor the use of these accessions in selection programs for commercial purposes, conservation and sustainable use.

“…Mature pollen was analyzed, of which the stained grains were considered viable and wrinkled or colorless grains unviable (Singh 1993). About 1000 mature pollen grains per plant were counted in four flowers per plant (250 pollen grains per plant), following the protocol established and used (Dahmer et al 2008, Guerra et al 2013, Krycki et al 2016. The pollen viability estimate was calculated by the percentage of viable grains: number of grains considered viable divided by the total number of grains multiplied by 100 (Tedesco et al 2019).…”

Section: Meiotic Chromosome Pairing and Pollen Viability Analysismentioning

confidence: 99%

“…Evaluation of fertility and analyses of the reproductive mode of the generated hybrids are necessary in breeding program, defining their usefulness and enabling intraspecific hybridizations (Krycki et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Reproductive analyses of intraspecific Paspalum notatum Flügge hybrids.

Krycki

Tedesco

Rodrigues

et al. 2020

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Paspalum notatum is an important forage native to Southern Brazil and one of the most promising fodder species in terms of productivity, quality, resistance and growth speed. The objective of this study was to evaluate the reproductive mode and fertility of hybrid progenies resulting from artificial crosses among artificially duplicated sexual plants, selected intraspecific hybrids of the UFRGS breeding program and apomictic ecotypes of the species. The resulting F 1 progenies were represented by 24 plants with high pollen viability (varying from 82.15 to 99.67%) and 1.2:1 segregation for the sexual: apomictic reproduction mode, indicating predominantly sexual hybrids, due to distorted segregation. In the apomictic plants, most chromosomes paired as bivalents in diakinesis. Since the low presence of abnormalities observed in the meiotic chromosome pairing and the high pollen viability of the hybrids, all plants were confirmed as promising parents for future crosses.