Impact of chitosan on shoot regeneration from faba bean embryo axes through its effect on phenolic compounds and endogenous hormones

Abstract

Legume crops have been the primary targets for improvement by genetic transformation due to their importance for human and animal consumption worldwide. Many of these important legume crops were difficult to genetically engineer especially faba bean crop, mainly due to high phenolics content and their recalcitrance to in vitro regeneration. Therefore, a series of experiments were performed in order to evaluate the growth , morphological changes and production of phenolics in the in vitro plantlets of five Egyptian faba bean cultivars (Giza 843, Sakha 1, Sakha 3, Nubaria 2 and Nubaria 3). The obtained results revealed that cultivars Nubaria 2 and Skha 3 had the highest regeneration frequency (85.3% and 78.6%), respectively. Also, both cultivars showed high growth parameters and low in total phenols concentration. Therefore, these cultivars considered as promising candidates to Agrobacterium mediated genetic transformation experiments. The effect of different levels of chitosan (0, 2, 4, 8, 15, 30, 60, and 120 mg chitosan/l) on shoot regeneration from mature embryo axes of cv. Nubaria 2 were studied. The obtained results indicated that high levels of chitosan have lethal effect on the development of embryo axes tissues and the plantlets showed morphological abnormalities. However, low levels of chitosan 2 mg /l and 4mg /l in combination with 4.5 mg/l BAP increased the shoot regeneration. Moreover, the total soluble phenols were increased by increasing the age of the faba bean plantlets (six weeks old) cultured in vitro on a medium containing low level of chitosan (2, 4 and 8 mg chitosan/l) as compared with plantlets did not expose to chitosan. HPLC analysis showed changes in the polyphenols concentrations and the concentration of Gibberellic acid (GA3) and Abscisic acid (ABA) in faba bean plantlets that exposed to low levels of chitosan (2, 4 and 8 mg chitosan /l) were increased as compared with control plantlets. The obtained results indicated that the concentration of phenolic compounds, GA3 and ABA in the extracts were increased in the faba bean plantlets that exposed to low levels of chitosan.file: :Users/u0129515/Sync/My_list_publication/Abeer, 2020.pdf:pdf keywords: ABA,Embryo Axes,GA3,Phenols,Regeneration Frequenc