Obtaining tetraploid plants of ruzigrass (Brachiaria ruziziensis)

Abstract

-The objective of the present work was to induce chromosome doubling in genotypes of Brachiaria ruziziensis with potential for production of good-quality biomass and tolerance/resistance to stress caused by aluminum and spittlebugs. Germinated seeds of B. ruziziensis were immersed in 0.1% colchicine solution for 2 or 3 hours. Ploidy level was determined by flow cytometry and confirmed by chromosome count. Fertility of the tetraploid plants was assessed through evaluation of pollen viability by staining. There was no statistical difference with regard to seedling survival and number of duplicate seedlings between the treatments. Survival rate was 8%, of which 11.45% were tetraploid genotypes. The mean viability of pollen grains from the evaluated tetraploid plants ranged from 51.75 to 55.50%. So, the tetraploids plants obtained from genotypes of a bred population of ruzigrass produce fertile pollen, in percentages that render crosses viable in genetic breeding programs.

Chromosome duplication in Lolium multiflorum Lam.

“…Variation in time of exposure to colchicine was also observed in the induction of chromosomal duplication of Brachiaria (Simioni and Valle 2009, Ishigaki et al 2009, Timbó et al 2014. The time of exposure to colchicine used was 48 h (Simioni and Valle 2009) and 2 and 3 h (Ishigaki et al 2009, Timbó et al 2014).…”

“…The time of exposure to colchicine used was 48 h (Simioni and Valle 2009) and 2 and 3 h (Ishigaki et al 2009, Timbó et al 2014). …”

Microsporogenesis analysis validates the use of artificially tetraploidized Brachiaria ruziziensis in breeding programs

“…The study was conducted using a B. ruziziensis genotype that had been artificially tetraploidized using colchicine (2n = 4x = 36) ('Iracema'; Timbó et al, 2014), a genotype of B. ruziziensis derived from a population obtained from the intercrossing of eight tetraploidized plants ('45'), and four genotypes obtained from selfing the tetraploidized B. ruziziensis plants ('1846', '1847', '1880', and '1881'). These genotypes are part of a B. ruziziensis breeding program that is run by Embrapa Dairy Cattle, Juiz de Fora, Minas Gerais State, Brazil.…”

“…Several duplication studies have been conducted on Brachiaria, including on seeds germinated in vivo (Swenne et al, 1981;Timbó et al, 2014) and the in vitro culture of germinated seeds, multiple shoots (Ishigaki et al, 2009), and basal segments (Pinheiro et al, 2000;Simioni and Valle, 2009). In general, successfully obtaining polyploids depends on several exogenous factors (Pereira et al, 2012), and the use of colchicine causes side effects such as sterility, abnormal growth, chromosomal loss or rearrangement, mutations (Luckett, 1989), and mixoploidy (Pereira et al, 2012).…”

“…The objective of this study was to comparatively evaluate the viability and morphology of pollen grains and meiosis in the 'Iracema' genotype of artificially tetraploidized B. ruziziensis plants (Timbó et al, 2014), in a B. ruziziensis genotype derived from the intercrossing of these tetraploidized plants, and in genotypes formed from the selfing of tetraploidized plants.…”