Duplication of the chromosome number of diploid Brachiaria brizantha plants using colchicine

Abstract

Some species of Brachiaria, generally tetraploid apomictic varieties, have become important forage grasses in the tropics. Breeding of Brachiaria depends on compatibility with the available apomitic tretraploid cultivars. This paper describes a procedure for chromosome duplication of two Bracharia brizantha diploid sexual accessions, using colchicine treatment of basal segments of in-vitro-grown plants. Explants were cultured on a medium containing 1 mg/l naphthaleneacetic acid, 3 mg/l kinetin and 0.01% colchicine for 48 h and transferred to the same medium without colchicine until shoot regeneration occurred. Regenerated plants were screened by flow cytometry, and chromosome number duplication was confirmed by cytological analysis of root tips.

Induction and identification of Stylosanthes guianensis tetraploids

“…In addition, induced polyploid breeding provides a wider germplasm base for breeding programs (Luckett, 1989;Aranada et al, 1997;Osborn et al, 2003;Shao et al, 2003;Thao et al, 2003;Comai, 2005;Omidbaigi et al, 2010). By preventing microtubule assembly and arresting spindle formation during mitosis, colchicine is conventionally and successfully used to induce chromosome doubling in the development of tetraploids (Takamura and Miyajima, 1996;Pinheiro et al, 2000;Nguyen et al, 2003;Petersen et al, 2003;Shao et al, 2003;Liu et al, 2007;Urwin et al, 2007).…”

Breeding tropical forages

“…The ploidy level characterization of this germplasm resulted in the discovery of a sexual accession, which was artificially doubled to make crosses with tetraploid accessions feasible (Pinheiro et al 2000). However, these plants flower much later than the B. brizantha accessions, so crosses have not yet been successful despite attempts to synchronize flowering of the progenitors.…”

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

“…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).…”