True-to-type micropropagated plants of para rubber (Hevea brasiliensis Müll. Arg.) via somatic embryogenesis

Abstract

Plant micropropagation via somatic embryogenesis is a powerful technique for rapid mass propagation, especially in para rubber (Hevea brasiliensis Müll. Arg.). However, somaclonal variations are the major limitation of this process. To date, DNA fingerprinting, i.e., RAPD (Randomly Amplified Polymorphic DNA), Star Codon Targeted (SCoT), and SSRs (Simple Sequence Repeats), is one of the most successful technologies to detect the genetic fidelity in the somatic embryos. The aim of present study was to induce somatic embryos from inner integument explants of para rubber cv. ‘RRIM 600’ at different developmental stages and subsequent acclimatization and transplantation (under greenhouse and field conditions) of the propagated seedlings. The genetic stability of the plants derived from somatic embryos was also analysed in comparison to the mother plant using RAPD, SCoT and SSRs markers. Somatic embryos derived from inner integuments of 5-week-old immature seeds after pollination were more efficient than older and younger seeds. In addition, para rubber mother plants cv. ‘RRIM600’ and plants derived from somatic embryogenesis demonstrated the same pattern of DNA fragments, as confirmed by three PCR-based techniques, RAPD, SCoT and SSRs, whereas these in the pattern were different from ‘RRIT 226’, ‘PB 235’, ‘PB 251’, ‘PB 255’ and ‘BMP 24’. Interestingly, T2 plant was found to possess somaclonal variations when compared with mother plant. Based on the results, we confirm that the plants derived from somatic embryogenesis of para rubber cv. ‘RRIM 600’ were true-to-type to that of ‘RRIM 600’ master stock.

Comparative growth response of three rubber (Hevea brasiliensis Muell. Arg) clones in somatic embryo propagation

“…The highest percentage of viable callus was observed in the PB 260 clone at 23.20%, while the lowest was in the PB 340 clone at 8.90% (in contrast to the white callus, which was at 38.64%). This result was compared to the report by Tisarum et al [31], which showed that the highest percentage of callus induction from clone RRIM 600 was 52.9% when using immature seeds at 5 weeks of age. Additionally, the percentage of embryogenic/viable callus was 42.75%, also observed from the 5-week-old seeds.…”

“…This difference may be attributed to the relatively lower number of SEs formed, leading to faster individual growth. Research by Tisarum et al [31] showed that SE derived from embryogenic callus was maximized at 33.3% for 5-week-old immature seeds, compared to 4-week-old seeds (15%) and 6-week-old seeds (7.2%). This result indicates that the percentage of induced SE remains relatively low.…”

“…The burning method is employed for surface sterilization when the explants are enclosed by a hard sheath. This method was also successful applied to clone RRIM 600 where immature seeds of varying ages (4, 5 and 6 weeks) were collected after pollination [31].…”

“…Micropropagation of rubber through SE has been successfully reported by researchers using different sources of explants such as anther [18][19][20][21][22][23], zygotic embrio [25], leaf [26][27] and integuments [27][28][29][30][31][32]. Carron and Ettiene [28] stated that somatic embryo formation was limited to only a few genotypes, the embryogenic capacity was short-lived, and there was a very low rate of conversion of embryos into plantlets.…”

Induction of Axillary Bud Swelling of Hevea brasiliensis to Regenerate Plants through Somatic Embryogenesis and Analysis of Genetic Stability

“…The occurrence of genetic and epigenetic changes is the main limitation in the micropropagation of Hevea clones [47]. Thus, it is important to confirm the genetic stability among the plants obtained through somatic embryogenesis [48]. One of the most effective cytogenetic methods for the estimation of genome size and ploidy in plants is flow cytometry.…”