In vitro Regeneration of Picralima nitida (Stapf). T. Durand & H. using Zygotic Embryo

Disinfected mature seed embryos of Picralima nitida, were cultured in MS medium supplemented with different concentrations and combinations of 2,4-D, BAP and NAA to determine an efficient protocol for in vitro propagation. Nine culture media made of combination of different components were used in a factorial design with three replications. Results showed up to 80 ± 4% disinfection rate with combination of triton x- 100 (0.2%) and sodium hypochlorite (30%). Embryo germination was highest on control medium. Rooting was higher (2±1 roots per embryo) after 4 weeks on control medium and on BAP supplemented medium at 0.8 μM while the longest root (1.5±0.5 cm) was observed on 2,4-D supplemented medium at 1.8 μM. Black soil was suitable for leaf formation (4 ± 2 leaves) and shoot elongation (2±1 cm) after 8 weeks in acclimatisation. These results show efficient disinfection, regeneration and acclimatisation of Picralima nitida. Plant Tissue Cult. & Biotech. 31(2): 143-151, 2021 (December)

Plant Regeneration and In Vitro Growth Performance of Male-Sterile Somatic Plantlets of Sugi (Japanese Cedar, Cryptomeria japonica) Derived from Different Embryogenic Cell Lines

With the spread of pollinosis caused by sugi (Japanese cedar, Cryptomeria japonica) pollen, the use of pollen-free somatic seedlings of sugi is expected in Japan. However, there is a lack of knowledge on the relationship between the abilities during somatic embryogenesis, initial in vitro growth traits, and subsequent growth of somatic seedlings. In the present study, we provide the first basic information on somatic embryo maturation efficiency, somatic embryo germination, and plantlet conversion frequencies, as well as on in vitro growth performance of pollen-free somatic plantlets derived from different embryogenic cell lines (ECLs). Somatic embryo maturation efficiency varied from 34 to 514 cotyledonary embryos per plate and the average for the 19 ECLs tested was 244 embryos per plate. Subsequently, the overall average rates of somatic embryo germination and conversion among ECLs were 87.8% and 85.3%, respectively. The results of in vitro growth performance of pollen-free somatic plantlets showed significant differences in growth rate among ECLs.

Development of an embryo germination protocol for shy-seeded grape (Vitis vinifera L.)

Acquisition and germination of seeds are the most desired targets for the improvement of vegetatively propagated crops. In the present study, we developed a potential embryo germination protocol for the Red Globe grape cultivar having a low seed germination rate. Three grape berries at different developmental stages, viz. 50, 60 and 70 days after flowering (DAF), were selected for in-vitro embryo germination. Three growth media, namely Emershad and Ramming (ER), Nitsch and Nitsch (NN) and Murashige and Skoog (MS), and plant growth regulators (benzyl amino purine (BA), 0.5, 0.7 and 0.9 mg/l; indole butyric acid (IBA), 1.0, 1.5 and 2.0 mg/l; and gibberellic acid (GA), 0.1, 0.3 and 0.9 mg/l) were screened individually in different combinations with three amino acids, namely cysteine, glutamine and proline (2.0 μmol/l each). The maximum embryos germination percentage recorded at 70 DAF was 63.33, 47.78 and 45.56% in ER, NN and MS media, respectively, supplemented with 0.9 mg/l BA, 2.0 mg/l IBA, 0.9 mg/l GA and 2.0 μmol glutamine. Glutamine was found to have the most significant impact, and it improved the rescued embryos germination. The present study provides a potential recipe for a medium that can facilitate efficient germination of grape embryos.

Hydropriming Improves Germination and Plant Recovery During Embryo Rescue of Wild Banana Musa acuminata var. tomentosa

Wild bananas are believed to have genes for resistance to biotic and abiotic stress in nature, making them potential genetic resources for creating superior varieties. Wild banana seeds, such as Musa acuminata var. tomentosa are generally difficult to germinate in vivo, so that in vitro embryo culture technique is needed. This study aimed to increase embryo germination and regeneration of wild banana M. acuminata var. tomentosa by soaking the seeds as hydropriming. The treatment comprised of soaking the seeds in sterile distilled water for four periods of time: 0 (control), 1, 4, and 7 days. A total of 45 embryos for each treatment were planted on petri dishes containing MS + 0.5 mg/L BA + 1 mg/L biotin + 1 mg/L proline. The results showed that hydropriming increased the rate of embryo germination and regeneration. Seeds soaked for 1, 4, and 7 days successfully resulted in embryo germination percentages of 87%, 62%, and 62%, respectively, while the control unsoaked seeds germinated with a lower percentage of 42%. One-day soaking treatment was the most optimal treatment to increase the rate of germination and regeneration as well as obtained the best vigor as demonstrated by the highest average height of plantlets, number of leaves, and roots than other treatments. Thus, 1-day seed hydropriming is the best treatment for embryo rescue and regeneration of wild banana M. acuminata var. tomentosa

Somatic-embryogenesis derived leaf-rust-tolerant clones of arabica coffee to deal with climate change

The high-altitude coffee growing, Arabica, is likely subject to the global warming effect as they are prone to leaf-rust attacks at a higher temperature. It supplied 70% of world coffee production for its popularity concerning its delicacy and aromatic flavor. Utilization of, genetically, superior planting materials, i.e. leaf-rust-tolerant Arabica, has become an essential point, as may provide the potential solution to prevent the lost production due to leaf-rust attack. Andungsari 2K (AS 2K), S795, AS1, and Sigararutang are some of the potential leaf-rust-tolerant Arabica clones in Indonesia. Vegetative propagation by somatic embryogenesis may support the availability of superior plant materials quickly. The major aim of this experiment was to study the effect of different clones on germination step after the preliminary stage of direct-embryogenesis from leaf explants with combinations of medium between auxin (2,4-D) and cytokinin (2-ip). Embryo germination stage where embryoid was transferred to the germination medium consisting of MS medium without hormones. The results revealed that the growth location and texture of callus, as well as growth patterns and colour of embryogenic callus, were significantly influenced through the different combinations of medium and clones. The clone of S795 exhibits the highest embryo germination percentage of up to 100% within 8 weeks experiment period.

Development of In vitro Tetraploid Plants of Hevea brasiliensis

Increase in global consumption of natural rubber necessitates crop improvement of Hevea aimed at increased productivity. As conventional breeding of Hevea is very elaborate and time consuming. Hence in the present study development of tetraploids through chromosome doubling of diploid callus obtained from cultured immature inflorescence of Hevea using colchicines were attempted. Chromosome doubling of the diploid callus occurred when treated with 1.25 µM colchicine for 3 days. In higher concentrations as well as at longer exposure periods, the callus texture and viability were affected. 48 % embryo induction and a maturation frequency of 45 % were obtained. Embryo germination and plant regeneration with a germination frequency (30 %) and a regeneration frequency (20 %) were obtained. Cytological and flow cytometric analyses confirmed the tetraploid nature of the colchicines treated callus. In vitro tetraploid plant developed through these in vitro techniques can be further used in Hevea brasiliensis breeding.

Effect of 2, 4-D and Picloram on Somatic Embryogenesis in Carica papaya var. P-7-9

Immature zygotic embryos of Carica papaya L. var. P-7-9 were inoculated on half-strength MS with different concentrations of 2,4-D and picloram alone and their combinations. The highest induction (80%) of somatic embryogenesis was MS supplemented with 2,4-D (7.0 mg/l) followed by 2,4-D (4.0 mg/l) + picloram (1.0 mg/l) but no embryogenesis was observed in auxin-free medium. The addition of osmoticum such as PEG and ABA significantly increased the maturation of somatic embryos. BAP, TDZ and NAA were used for shoot induction. Combination of 2.0 mg/l BAP and 0.5 mg/l NAA was found significantly better for shoot bud proliferation and 70% multiplication. The percentage of germinating embryos was enhanced significantly when the MS fortified with GA3 (0.5 mg/l). However, the high frequency of embryo germination and plantlets formation were obtained with 2,4-D (4.0 mg/l) + picloram (1.0 mg/l). Plant Tissue Cult. & Biotech. 29(1): 25-32, 2019 (June)