Induction of somatic embryogenesis (SE) in recalcitrant Musa spp. by media manipulation based on SE’s molecular mechanism

Somatic embryogenesis (SE) is a high-throughput technique for the large-scale production of quality planting material, genetic transformation and mutation breeding.
Although SE is well reported in selected banana cultivars, most of the commercial cultivars are recalcitrant for SE. In order to induce SE in recalcitrant genotypes through media manipulation, knowledge on genes responsible for SE is of paramount importance.
Our earlier studies on comparative proteomic profiling between embryogenic calli (EC) and non-embryogenic calli, and between germinating and non-germinating somatic embryos of ‘Grand Naine’ (AAA), have identified putative genes responsible for EC induction and germination of somatic embryos.
Based on the results of these studies, callus induction media were manipulated in four recalcitrant cultivars possessing different genomic constitution (‘Red Banana’ (AAA), ‘Monthan’ (ABB), ‘Karpuravalli’ (ABB) and ‘Ney Poovan’ (AB)) and one responsive cultivar (‘Grand Naine’). In total, 375 explants of each cultivar were initiated from male flower buds on different media combinations.
After 5-8 months of explant initiation, EC induction was recorded.
In ‘Grand Naine’, media with increased concentrations of indole acetic acid (IAA) recorded highest EC induction of 24.28%, while the other AAA-cultivar ‘Red Banana’ showed 18.96% EC induction in kinetin-supplemented media.
Similarly, ABB-cultivars ‘Monthan’ and ‘Karpuravalli’ showed maximum EC induction in tryptophan-supplemented media (8.54%) and CaCl₂-enriched media (17.34%), respectively.
In ‘Ney Poovan’ (AB), higher concentration of tryptophan induced more EC (27.44%). These results illustrate that EC formation in banana is not only dependent on genome constitution but also on the cultivar.
Simultaneously, germination media have been modified to induce the proteins responsible for germination of somatic embryos.
In ‘Grand Naine’, media supplemented with 1 mg L^‑1 1-naphthaleneacetic acid (NAA) and 0.5 mg L^‑1 gibberellic acid (GA₃) showed highest germination of 91.0%, whereas in ‘Rasthali’, 10 mM CaCl₂-enriched media showed maximum germination of 91.2%. Thus, this present study revealed that media augmentation based on proteomic studies can trigger EC in recalcitrant banana cultivars and germination efficiency in cultivars showing better response for SE.

XXX International Horticultural Congress IHC2018: XI International Symposium on Banana: ISHS-ProMusa Symposium onGrowing and Marketing Banana under Subtropical Conditions

M. Kumaravel, S. Backiyarani, M.S. Saraswathi, K. Arun, S. Uma

embryogenic calli, recalcitrant, somatic embryo, germination, media modification, proteomics

https://doi.org/10.17660/ActaHortic.2020.1272.15