Morphology and pollen viability of Lolium multiflorum Lam.

Abstract

Study and characterization of pollen grains are essential for different areas, especially taxonomy, genetic improvement, phylogeny, and paleobotany. As yet, there are no reports on pollen morphology of genotypes of naturalized Lolium multiflorum Lam., introduced cultivars or breeding populations, diploid or polyploid. Ten genotypes of annual ryegrass (L. multiflorum) were evaluated for the viability of pollen grains using propionic carmine and Alexander's stains, while morphology was assessed by the acetolysis technique. Measures of polar axis (P), equatorial diameter (E), exine thickness, and analysis of pollen grains were obtained by scanning electron microscopy (SEM). All genotypes showed high rate of pollen viability (> 89%) for both stains. There were differences between genotypes in the following quantitative traits: polar axis, equatorial diameter, exine, endexine, ektexine, and P/E ratio. Pollen grains were characterized as small, monoporates, with circular and non-prominent apertures. In addition to helping distinction of pollen grains, morphometric differences can be used later to compare ploidy levels, thus assisting in breeding programs of the species.Index terms: Scanning electron microscopy, ryegrass, acetolysis. RESUMOO estudo e a caracterização do grão de pólen são fundamentais para diferentes áreas, em especial, para a taxonomia, o melhoramento genético, a filogenia e a paleobotânica. Para genótipos de Lolium multiflorum Lam., naturalizados no Brasil, cultivares introduzidas ou populações de melhoramento, diploides e poliploides, não existem relatos sobre a caracterização morfopolínica. Nesse trabalho foram analisados dez gentótipos de azevém anual (L. multiflorum). A viabilidade dos grãos de pólen foi verificada por coloração com os corantes carmim propiônico e Alexander e a morfologia por meio da técnica de acetólise, sendo obtidas medidas do eixo polar (P), do diâmetro equatorial (E), e da espessura da exina, e análise dos grãos de pólen por microscopia eletrônica de varredura (MEV). Todos os genótipos avaliados apresentaram alta taxa de viabilidade polínica (>89%) para os dois corantes utilizados. Houve diferença entre os genótipos para os caracteres quantitativos eixo polar, diâmetro equatorial na vista equatorial, exina, endoexina, ectoexina e razão P/E. Os grãos de pólen foram caracterizados como pequenos, monoaperturados, com abertura não proeminente e com âmbito circular. As diferenças morfométricas entre os grãos-de-pólen podem auxiliar na distinção entre os mesmos e, posteriormente, serem utilizadas para comparação entre os níveis de ploidia, auxiliando, assim, nos programas de melhoramento da espécie.Termos para indexação: Microscopia de varredura, azevém, acetólise.

Anthropic pollen indicators: poaceae pollen of non-native species in Southern Brazil

“…13 The same occurred with Avena strigosa and Avena sativa with pollen grains previously measured 42 and 16 with pollen size similar to our study. In the pollen grains of Lolium multiflorum, we observed sizes slightly larger than those measured, 12 on the other hand, our measurements are similar to those obtained by 11 who also described the pollen grains of this specie. While Poa annua showed pollen grains of similar size to the same species described by Salgado-Labouriau and, 18 the size of the pollen grain of Triticum sp.…”

“…10 On the other hand, other cultivated species such as ryegrass (Lolium multiflorum) have pollen grains that cannot be distinguished from native Brazilian taxa. 11,12 Figure 1 Pollen grains records of Zea mays (corn) in Quaternary sediments of Rio Grande do Sul state and the ages what the pollen of Zea mays were founded in the sediment according to. [4][5][6][7] The other studies on pollen grains of cultivated grasses focused on the analysis of the exine surfaces by scanning electron microscopy of species of rice-Oryza, 13,14 sugar cane-Saccharum, 15 oat-Avena [14][15][16][17] and wheat-Triticum.…”

Phosphorus application and liming effects on forage production, floristic composition and soil chemical properties in the Campos biome, southern Brazil

“…On all treatments except the control, seeds of winter‐growing species were introduced by oversowing. Italian ryegrass ( L. multiflorum genotype Comum) (Nunes et al ., ; MAPA, ) and arrowleaf clover ( T. vesiculosum cv. Yuchi) (Frame, ) were oversown in lines on to the surface of the natural grassland sward at seeding rates of 30 and 12 kg ha −1 , respectively, on 29 May 1997.…”

Chromosome duplication in Lolium multiflorum Lam.

“…Studies by Nunes et al (2012) with genotypes of Lolium multiflorum, including two tetraploids, showed higher rates (above 90%) of pollen viability. The authors suggested that the high rate of functional pollen in these genotypes may be associated with meiotic regularity and regular collection timings (8:30 a.m. to 10:00 a.m.) when anther dehiscence begins, implying that viability reaches its maximum.…”