Theme 2: Forage--Oral Sessions

Description

Tetraploid ruzigrass (Brachiaria ruziziensis) have been obtained by colchicine treatment of in vitro apical meristems and embryogenic calli. The colchicine treatment consisted of culturing apical meristem on MS basal medium containing 6.0 mg L-1 6-benzylaminopurine (BAP) and 0.05-0.20% colchicine for 8, 14, 20 and 26 h. After treated by colchicine, apical meristems were transferred onto former medium without colchicine for 4 weeks. Surviving apical meristems were induced multiple roots on MS basal medium containing 2.0 mg L-1 BAP. The ploidy level of plants after colchicine treatment was determined by flow cytometry. Apical meristems treated with 0.05% colchicine for 26 h. was identified as the optimum treatment and resulted in the highest frequency (13.3%) of tetraploid plants among the treatments tested on apical meristems. Embryogenic calli were induced on MS basal medium supplemented with 5.0 mg L-1 2,4-dichlorophenoxy acetic acid (2,4-D), 1.0 g L-1 casein hydrolysate, 0.5 mg L-1 kinetin and 5% coconut water. The colchicine treatment consisted of culturing embryogenic calli on MS basal medium containing 1.0 mg L-1 kinetin, 0.1 mg L-1 1-napthaleneacetic acid (NAA) and 0.05-0.20% colchicine for 8, 14, 20 and 26 h. After treated by colchicine, embryogenic calli were transferred onto former medium without colchicine for 4 weeks. Shoots from embryogenic calli survived were induced multiple roots on MS basal medium containing 2.0 mg L-1 BAP. Two tetraploid plants were obtained from embryogenic calli treated with 0.10% colchicine for 14 h and 0.15% colchicine for 26 h. Total of 16 tetraploid genotypes were clonal propagated and grew in the field, with 1 diploid genotype as the control. It was found that the mean ± standard deviation of thousand seed weight (TSW) of all genotypes, tetraploid genotypes were 8.119 ±1.36 and 8.239 ±1.30 g, respectively, whereas TSW of diploid one was 6.209 g.

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Induction of Tetraploid Ruzigrass (Brachiaria ruziziensis) by Colchicine and Possibility of Using Seed Weight as Screening Method

Tetraploid ruzigrass (Brachiaria ruziziensis) have been obtained by colchicine treatment of in vitro apical meristems and embryogenic calli. The colchicine treatment consisted of culturing apical meristem on MS basal medium containing 6.0 mg L-1 6-benzylaminopurine (BAP) and 0.05-0.20% colchicine for 8, 14, 20 and 26 h. After treated by colchicine, apical meristems were transferred onto former medium without colchicine for 4 weeks. Surviving apical meristems were induced multiple roots on MS basal medium containing 2.0 mg L-1 BAP. The ploidy level of plants after colchicine treatment was determined by flow cytometry. Apical meristems treated with 0.05% colchicine for 26 h. was identified as the optimum treatment and resulted in the highest frequency (13.3%) of tetraploid plants among the treatments tested on apical meristems. Embryogenic calli were induced on MS basal medium supplemented with 5.0 mg L-1 2,4-dichlorophenoxy acetic acid (2,4-D), 1.0 g L-1 casein hydrolysate, 0.5 mg L-1 kinetin and 5% coconut water. The colchicine treatment consisted of culturing embryogenic calli on MS basal medium containing 1.0 mg L-1 kinetin, 0.1 mg L-1 1-napthaleneacetic acid (NAA) and 0.05-0.20% colchicine for 8, 14, 20 and 26 h. After treated by colchicine, embryogenic calli were transferred onto former medium without colchicine for 4 weeks. Shoots from embryogenic calli survived were induced multiple roots on MS basal medium containing 2.0 mg L-1 BAP. Two tetraploid plants were obtained from embryogenic calli treated with 0.10% colchicine for 14 h and 0.15% colchicine for 26 h. Total of 16 tetraploid genotypes were clonal propagated and grew in the field, with 1 diploid genotype as the control. It was found that the mean ± standard deviation of thousand seed weight (TSW) of all genotypes, tetraploid genotypes were 8.119 ±1.36 and 8.239 ±1.30 g, respectively, whereas TSW of diploid one was 6.209 g.