The impact of salinity stress on morphological and anatomical aspect of water hyssop Bacopa monnieri (L.) Wettst grown in vitro

This study was conducted at Marine Science Center, Basrah University, Basrah, Iraq during the period of 2015 to 2016. In the present work, we used NaCl and polyethylene glycol (PEG) to induced abiotic stress in vitro. Results show that high shoot numbers (24) were produced on MS (solid) medium enriched with 0.8 g/L NaCl in addition to cytokinins while, inclusion of drought agent PEG to proliferation medium (solid and liquid) produced a minimum shoots of 5 and 11 respectively. Root growth and development were also investigated in this study. It was found that high root development was observed on MS (solid or liquid) medium free of hormone (control) and MS (solid or liquid) medium containing 0.8 g/L NaCl 26.67, 25, 21.67 and 18 respectively whereas, less root development was obtained on MS medium (solid or liquid) enriched with NaCl and 26 g/L PEG. In this study it was found that inclusion of the amino acid proline to the stressed media did not improve the growth of shoots or roots. Histological analysis of multiplied shoots under abiotic stress agents showed accumulation of insoluble starch granules in the parenchyma cells of the cortex layer and this may be a part of protective tolerate mechanism used by medicinal hyssop (Bacopa monnieri) against abiotic stress.   Key words: Bacopa monnieri, medicinal hyssop, Brbin, micropropagation, salt stress, polyethylene glycol (PEG), proline.