Somaclonal Variation in Callus Cultures of Rose Periwinkle, <i>Catharanthus Roseus L</i>. Under Induced Salt and Osmotic Stresses

Abstract

The experiment was carried out at the laboratories of the National Commission for Biotechnology in Syria during the period 2020-2022 to detect the somaclonal genetic variation occurring in callus cultures at different ages and to compare them with the <em>In vitro</em> growing plants<em> </em>and<em> </em>introduced species of Rose Periwinkle that grew up in the Syrian environment, in addition, exploring the effect of abiotic stresses in causing genetic variations in callus, by the Inter Simple Sequence Repeats technique (ISSR) using 21 primers. Seeds were germinated on an MS nutrient medium devoid of growth regulators; explants were transferred to a propagation medium fortified with Naphthalene Acetic Acid (NAA) (1 mg L<sup>-1</sup>) and 6-Benzyladenine (BA) (2 mg L<sup>-1</sup>). Callus was developed from Rose periwinkle <em>Catharanthus roseus L</em>. leaves using 5C01 medium fortified with NAA and Kinetin (Kin). After that, callus was exposed to gradually increasing levels of PEG-6000-induced osmotic stress and salt stress (NaCl) with a higher level every 30 days. The molecular study results proved the effectiveness of all the used primers (21 primers) in presenting polymorphism between the studied samples at a rate of 92.16%. The cluster analysis showed separating the analyzed samples into two main clusters. The first cluster contained the osmotic stressed callus, while the second cluster separated into two sub-clusters that had the rest of the studied samples. It was found that there were genetic variations between <em>In vitro</em> plants and the callus. In addition, the stressed callus (salt and osmotic) was compared to the unstressed callus, and this confirmed that callus cultures were an essential source of genetic variations, and the ISSR technique was an effective tool for detecting these variations.