OPTIMIZATION OF KINETIN CONCENTRATIONS AND MEDIUM COMPOSITIONS FOR CITRUS SHOOT MULTIPLICATION FROM COTYLEDONARY NODES

Abstract

Shoot multiplication plays an important role in tissue culture activities; therefore, it should be optimized via several factors, such as the composition of the medium and the concentration of plant growth regulators. The aim of this study is to optimize the kinetin concentrations and medium compositions for shoot multiplication originating from cotyledonary node explants of several local citrus cultivars for genome editing activities. The cotyledonary nodes from three citrus cultivars (Batu55, Siam Madu, and Proksi-1 Agrihorti) were incubated in MS medium with Morel and Wetmore vitamins (VMW) supplemented with several kinetin concentrations (0; 0.2; 0.4; 0.6; 0.8; and 1 mg/L). The best kinetin concentrations for the number of shoots variable were then combined with Murashige and Tucker (MT) medium. The results showed that the combination of VMW medium and kinetin concentration at 0.8 mg/L produced the best number of shoots in Batu55 cultivar as well as 1 mg/L concentration in Siam Madu and Proksi-1 Agrihorti cultivars. Therefore, those two concentrations were then chosen to be combined with MT medium in the second experiment. The results showed that combination of 1 mg/L kinetin with MT medium showed the best number of shoots, the highest percentage of shoot formation, the biggest number of leaves, the biggest number of nodes, and the longest shoot length in this study. This medium composition could be further used for shoot multiplication in genetic transformation in those three citrus cultivars, including genome editing activities in the development of new improved citrus varieties.