Development of an efficient in vitro protocol to increase callus induction and regeneration rate in soybeans (Glycine max L. Merrill)

Abstract

Soybean is a legume crop that is highly dependent on various parameters and is difficult to maintain in vitro. Tissue culture techniques have been optimized to develop a standardized methodology for soybean. The most significant constraints that impede the efficacy of current techniques in soybean tissue culture studies are commonly dependent on the genotype, explant type, and media composition. In this study, the frequency of callus formation and the regeneration capacity of three different cultivars, Arısoy, Nova and Blaze, that had not previously been investigated in vitro were evaluated for various media contents, CIM1 (1 mg L− 1 2,4-D + 0.1 mg L− 1 Kinetin), CIM2 (2 mg L− 1 BAP + 2 mg L− 1 NAA) and CIM3 (1 mg L− 1 BAP + 0.1 mg L− 1 NAA + 0.1 mg L− 1 GA3 + 0.1 mg L− 1 TDZ), and explant types, cotyledonary leaves, cotyledonary node, embryo and hypocotyl. The highest calli induction for Arısoy, Nova, and Blaze cultivars was obtained at CIM1 (70%), CIM2 (56%), and CIM3 (56%) in terms of media composition, and in hypocotyl (98%) and embryo (66% and 65%) as explant types. The interactions of all CIM × hypocotyl (98%) and CIM1 × cotyledonary node (100%) for Arısoy, and CIM1 × embryos (91%) and CIM2 × embryos (100%) for Nova and Blaze, respectively, had the greatest rate of calli production. Arısoy was determined to be the best cultivar for callus response based on all treatments. The calli of both Arısoy and Nova cultivars achieved a regeneration rate of 22% and 14%, respectively, when transferred to regeneration medium containing 0.45 µM TDZ, however with only cotyledonary nodes showing shoot initiation and elongation. As these cultivars have not previously been studied in vitro in terms of callus response and regeneration, it is expected that they will play an important role in genetic transformation studies in the future.