Optimizing Temperature and Light Conditions for In vitro Conservation of Commiphora wightii (Arn.) Bhandari Callus Cultures

Abstract

In vitro conservation technique is one of the potential approaches to safeguard plant biodiversity. To protect the important germplasm, storage of whole plant can be challenging. A study was done to conserve the callus of Commiphora wightii at different temperatures i.e. 4°C, 10°C, 20°C, 30°C and 40°C for a longer period of time as well as the effect of light and dark on callus of Commiphora wightii was observed. The callus was initiated from immature fruits of C. wightii on Gamborg B5 medium supplemented with (0.5mg/l) 2, 4 D, 3% sucrose and 0.8% agar and was sub-cultured on same media at a regular interval of 30-35 days. After two passages vigorous callus growth was obtained and thus these proliferated cultures were further placed on two separate parameters which are different temperatures and dark/light experiment on hormone-free B5 medium. The morphological changes and the fresh weight of the callus cultures were analyzed. The cultures on different temperatures were stored for a period of 90 days without sub-culturing and the data was collected on every 30 days interval. It was found that at 10°C, 100% callus survived for 90 days and turned green, compact depicting the embryogenic nature, whereas at optimum temperature the sub-culturing was required after a period of 45-50 days. When the effect of dark and light was studied, the survival of callus kept in dark was 120 days which was around 60 days longer than the callus stored in light without sub-culturing. The callus stored in dark turned from non-embryogenic (white and friable) to embryogenic (green and compact). The survival percentage reduced after a period of 100-120 days for the cultures stored in dark. Our study suggests the feasibility of germplasm storage for species with recalcitrant seeds and facilitates germplasm shipments for conservation of forest species.