Optimize 2,4-D concentration and callus induction time enhance callus proliferation and plant regeneration of three rice genotypes

Carsono N, Juwendah E, Liberty, Sari S, Damayanti F, Rachmadi M. 2021. Optimize 2,4-D concentration and callus induction time enhance callus proliferation and plant regeneration of three rice genotypes. Biodiversitas 22: 2555-2560. The development of callus in the course of transgenic rice avoids the somaclonal variants. To obtain a high number of normal phenotypes and a low number of somaclonal variants requires an appropriate 2,4-D concentration. In this study, we obtained the best callus induction time and a high number of green plant regeneration for three responsive rice genotypes on different 2,4-D concentrations in NB5 medium. The mature seeds of rice embryos were used as explants. A completely randomized factorial design was applied with four levels of 2,4-D concentrations (0, 1, 3, and 5 ppm), two levels of induction time (one and two weeks), and three rice genotypes (cv. Fatmawati, Nipponbare, and Kitaake). The study revealed that there was no interaction effect among genotype, 2,4-D concentration, and callus induction time. Three rice genotypes performed best in callus proliferation and regeneration. One-week callus induction time showed higher callus growth capacity (CGC) as compared to two-week callus induction time. Shoot regeneration capacity (SRC) was independently affected by genotype as well as by callus induction time. The interaction effect between 2,4-D concentration and callus induction time was observed on plant regeneration capacity (PRC). Without the addition of 2,4-D and 1 ppm of 2,4-D, the green plant regeneration capacity (GRC) was comparatively higher. Addition of 2,4-D showed a significant effect, especially at the plant regeneration stage. We found that one-week callus induction was the best treatment for callus proliferation and plant regeneration. We recommend the use of one-week callus induction and 1 ppm of 2,4-D for rice callus proliferation (sub-culture) and subsequent plant regeneration.

Molecular Diversity Analysis of Somaclonal Variants of Potato (Solanum tuberosum L.) by Random Amplified Polymorphic DNA Markers

Aims: An experiment was conducted to analyze the DNA fingerprinting and genetic diversity of nine potato (Solanum tuberosum L.) somaclonal variants and three check varieties. Place and Duration of Study: The experiment was carried out at the Biotechnology laboratory of the Department of Biotechnology, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Dhaka-1207, Bangladesh during November, 2013 to December, 2014. Methodology: The somaclonal variants investigated were SIP-3, SIP-5, SVP-6, SVP-18, SVP-19, SVP-25, SVP-55, SVP-56 and SVP-68, while the check varieties were Cardinal, Diamant and Asterix. Six RAPD primers were used to perform PCR reaction after genomic DNA was extracted from young leaves. Results: The selected 6 primers produced total 54 distinct and differential amplified DNA bands of size range 88 bp to 3265 bp, where 47 bands (~87%) were polymorphic and 7 bands (~13%) were monomorphic. The pair-wise inter-genotype similarity indices were ranged from 61.59% to 93.55% with an average of 74.31%. The Nei’s genetic distance among 12 potato genotypes was estimated from 0.0972 to 0.6217 whereas, genetic identity was between 0.5370 and 0.9074. Here, the distantly linked accessions among the somaclonal variations with check varieties were SVP-6 (to Cardinal and Diamant) and SVP-25 (to Asterix). In addition, the UPGMA dendrogram segregated the 12 potato genotypes into two broad clusters containing 8 and 4 genotypes, respectively. Furthermore, the dendrogram also displayed the highest genetic distance between SVP-6 vs SVP-68 genotype pair. Conclusion: Significant relationship and diversity were found among the studied 12 genotypes. This genetic diversity among the potato genotypes would be utilized for further potato improvement.

Selection of somaclonal variants of maracuyá (passiflora Edulis var Flavicarpa. Deneger) tolerants to water deficit

Climate change will have an impact on the Colombian agricultural sector, by 2050 increases in temperature and distribution of erratic rainfall are expected. Passion fruit cultivation does not tolerate water deficit, it reduces flower induction, generates fruit drop and defoliation. To tackle this problem, somaclonal variants (VS) of passion fruit were selected in-vitro, seeking tolerance to water deficit. Four phases were developed: I) callogenesis, II) direct and indirect organogenesis, II) Induction and evaluation of the water deficit with Polyethylene glycol 6000 (PEG 6000) and IV) in vitro selection of VS by morphometric measurements, chlorophyll and total sugars contents. Differences in callogenesis were found with different concentrations of 2,4-D, the concentration of 2 mg • L-1 presented better results producing calluses in less time and in greater quantity (8 days, 90% of the leaf area). In indirect and direct organogenesis the medium MS + ANA + BAP (0.3: 0.6), showed significant statistical differences with respect to other means, for the variables root length (15.14 cm), stem (16.72 cm) and leaves ( 14.51 cm) and root thickness (0.76 cm) stem (1.25) and leaf width (6.75). The influence of PEG 6000 showed significant differences, the treatment with 30 g • L-1 showed the smallest leaf width, the greatest width was found in 25 g • L-1. Statistical differences were found in chlorophyll levels and total sugar contents, the highest contents were recorded in the VS 25VS1, showing the possibility of obtaining seedlings tolerant to the water deficit of passion fruit by inducing somaclonal variation.

Selection of somaclonal variants of the cultivar ‘Prata-Anã’ for resistance to Fusarium oxysporum f. sp. cubense race 1

The banana tree is one of the most cultivated fruit globally; however, some diseases significantly affect its production, such as Fusarium wilt. The most appropriate measure for controlling this disease in areas with inoculum pressure is the use of resistant cultivars. Therefore, this study aimed to generate banana somaclones of the cultivar ‘Prata-Anã’ resistant to Fusarium wilt by inducing somaclonal variation. ‘Prata-Anã’ stem apexes were established in vitro in MS culture medium and, on a monthly basis, subcultivated in AIA and adenine sulfate supplemented MS medium with added plant regulators: 6-benzylaminopurine (BAP, 4 ml L-1), Thidiazuron (TDZ, 1 ml L-1), and Paclobutrazol (PBZ, 10 ml L-1). The treatments were: T0: no regulator, T1: BAP, T2: TDZ, T3: PBZ, T4: BAP + TDZ, T5: BAP + PBZ, T6: TDZ + PBZ, and T7: BAP + TDZ + PBZ. After the twelfth subculture, the regenerated plants were planted in boxes containing sterile soil infected with Fusarium oxysporum f. sp. cubense, and evaluated after 90 days for resistance to the pathogen. Somaclonal variants T2-1 and T2-2, generated in Treatment 2, with TDZ, were selected as resistant. This result is promising for the launch of a new Fusarium race 1-resistant banana variety.