Dormancy breaking of Zataria multiflora seeds through tissue culture

Introduction: Zataria multiflora Boiss is a plant from the Lamiaceae family. This plant has been observed in Iran, Afghanistan, and Pakistan (Jamzad, ۲۰۱۲). The aerial parts of this plant are of great interest for relieving cough and respiratory disorders. Due to their high thymol and carvacrol content, they have antioxidant, antiseptic, antibacterial, and anti-inflammatory effects (Ghorani et al., ۲۰۲۲). The seeds of Z. multiflora have deep seed dormancy, which prevents them from germinating under suitable environmental conditions. There are several reports on using in vitro propagation methods and plant tissue culture techniques to overcome seed dormancy in various plant species. However, there is no literature report on the in vitro germination of Z. multiflora seeds; the innovation of the present plan is based on this matter. Materials and methods: The seeds of Z. multiflora were first washed under running water for ۱ hour and then transferred under a laminar flow hood. One group of seeds was soaked in a ۷۰% ethanol solution for ۱ minute, while another group proceeded to the next step without the ethanol wash. Both groups were shaken with sodium hypochlorite solution (۱.۵% and ۲%) for ۴ minutes. Finally, the seeds were washed three times with sterile distilled water. The seeds were then cultured in MS culture medium (Murashige & Skoog, ۱۹۶۲) and ½ MS (MS culture medium with salts reduced by half) with and without an amino acid complex (۵ ml/l). They were kept under environmental conditions with a photoperiod of ۱۶ hours of light and ۸ hours of darkness, at a temperature of ۲۵ ± ۲°C, and a light intensity of ۲۵۰۰ lux. After ۴ weeks, the germination percentage of the seeds was evaluated. The amount and type of amino acids used in the complex formulation (Inagrosa Company, Spain), based on the percentage of total amino acids, are as follows: glycine ۱.۸%, valine ۵.۱%, proline ۸.۴%, alanine ۱۳.۲%, aspartic acid ۴.۵%, arginine ۸.۴%, glutamic acid ۰.۹%, lysine ۵.۱%, leucine ۱۶.۵%, isoleucine ۴.۵%, phenylalanine ۵.۱%, methionine ۴.۲%, serine ۳.۹%, threonine ۳%, histidine ۳%, tyrosine ۱.۵%, glycine ۹.۶%, glutamine ۰.۹%, and cysteine ۰.۳%. All the experiments were designed and carried out in a factorial and completely randomized design with three replications. Results and Discussion: The analysis of variance on the percentage of contamination showed that only the effect of sodium hypochlorite concentration was significant at the ۹۵% probability level. This means that the only effective factor in the contamination percentage was the concentration of sodium hypochlorite. Mean comparisons also showed that the contamination rate of seeds treated with ۲% sodium hypochlorite (۸%) was lower than that of seeds treated with ۱.۵% sodium hypochlorite (۱۹.۲%). The analysis of variance in the percentage of seed germination showed that the interaction effect of sodium hypochlorite and the amino acid complex was significant at the ۹۹% probability level. Based on the results of the mean comparison, the highest germination rate (۱۰۰%) was observed with the combined treatment of ۲% sodium hypochlorite and the amino acid complex at a concentration of ۵ ml/l. According to studies, hypochlorite solutions (sodium or calcium) have been effective in most cases. For example, research results showed that during the surface disinfection method, a low concentration of sodium hypochlorite for a long time produced good results for surface disinfection and Passiflora caerulea seed germination (Jafari et al., ۲۰۱۶). Regarding the use and role of amino acids on various plants, including vegetables, trees, and fodder plants, there are valuable reports in the literature (Thomas et al., ۲۰۰۹).

کلیدواژه ها:

Zataria multiflora ، seed dormancy ، tissue culture ، germination ، sodium hypochlorite ، amino acids