Somatic embryogenesis and organogenesis in apomictic and sexual Brachiaria brizantha

Abstract

Brachiaria brizantha (syn. Urochloa brizantha) is an important tropical forage grass widely cultivated in Brazil. In order to optimize tissue culture conditions for B. brizantha, in vitro culture of mature seeds, basal segments and leaf segments from in vitro plants of an apomictic and a sexual genotype of B. brizantha was performed. When cultured on different media, leaf segments yielded nonembryogenic calluses which formed several roots. Friable calluses from mature seeds and basal segments explants incubated on Murashige and Skoog medium supplemented with 2,4-dichlorophenoxyacetic acid and 6-benzyladenine yielded 80% compact and nodular embryogenic structures. Calluses with such compact embryogenic structures were highly regenerable upon transfer to medium supplemented with kinetin and naphthalene acetic acid. They produced isolated somatic embryos, multiple fused scutelli or isolated scutellum with polyembryos that germinated into isolated or multiple shoots. Green and morphologically normal plants were obtained for the two genotypes. Changing the media from pH 5.8 to pH 4.0 increased the number of explants that formed calluses as well as the number of shoots per explant. When embryogenic calluses from mature seeds were successively sub-cultured for 4 months, aiming at repetitive somatic embryogenesis, all the regenerated plants were albinos. The embryogenic nature of the compact structure was confirmed by scanning electron microscopy.

Plant regeneration from embryogenic callus and cell suspensions of Brachiaria brizantha

“…1A). These results are in accordance with previous observations showing high efficiency of the M1.3/MS3 media combination for inducing and regenerating plants via somatic embryogenesis in B. brizantha (Cabral et al 2011). The profuse development of roots, regardless of the induction medium, was more frequent in NBreg than in MS3 medium (Fig.…”

“…Similar behavior was observed in bud formation in Brachiaria spp. on micropropagation medium (Cabral et al 2011). The induction/regeneration media combination NB/NBreg was originally used for rice somatic embryogenesis (Sallaud et al 2003), and even though these media are richer in free amino acids than M1.3/MS3, the best response for B. brizantha was obtained with the M1.3/MS3…”

“…The formation of multiple shoots was reported in cultured basal segments from micropropagated plantlets of this cultivar (Pinheiro et al 2000), a system that was efficient for in vitro chromosome duplication in Brachiaria. Somatic embryogenesis and organogenesis in B. brizantha is influenced by several factors such as genotype, explant type, and culture conditions (Cabral et al 2011).…”

Factors influencing Agrobacterium-mediated transformation of switchgrass cultivars

“…Unlike some direct plant regeneration systems (without a callusing stage) using the shoot apices as explants, we found in our preliminary studies that the white basal parts of newly germinated seedlings of 'Alamo' were readily available and had high capability of producing regenerable calluses. Similar results have recently been reported on signalgrass (Brachia brizantha), for which highly regenerable calluses were induced from mature seeds as well as basal segments of in vitro seedlings (Cabral et al 2011). Additionally, switchgrass seedlings have been reported to be susceptible to the infection of A. tumefaciens strains (Chen et al 2010).…”

Somatic embryogenesis of the heavy metal accumulator Prosopis laevigata

“…Some studies have demonstrated that 2,4-D and BA also induce the somatic embryogenesis, e.g. in Brachiaria brizantha cultures (Cabral et al 2011).…”