Screening of factors affecting somatic callusing and embryo induction in Allium cepa L. through Plackett–Burman methodology

Abstract

Induction of embryonic callus through available asexual explant culture is applied in the protection and maintenanceof cytoplasmic-male sterility and in the maintenance of other lines of onion (Allium cepa L.). Usage of the Plackett–Burman (PB)experimental design has been suggested as a screening method for many variables that influence the desired induction. In order toovercome limitations of standard experimental designs and prioritization of media culture components, a systematic investigation wascarried out using the PB design. In this investigation, the effects of different factors such as 2,4-D, putrescine, carbohydrate sources(maltose, sorbitol, and sucrose), silver nitrate, glutamine, and glycine concentrations were assayed on callus and embryo inductionthrough mature zygotic embryo explant culture. Out of the eight medium components screened, the four components of putrescine,glutamine, 2,4-D, and glycine were found to contribute positively to the callus production with a maximum production rate of 97.14%.The normal plot and linear regression equation with positive largest coefficient showed that putrescine had the highest significantpositive effect with 200 mg/L and three elements comprising 2,4-D and glycine showing a significant reducing effect on callus induction.In embryonic callus induction, a wide range of responses were observed from 0% to 100% in the 21 trials. Results of linear regressiondata showed that among the eight elements, 2,4-D, glutamine, and glycine had significant effects on embryo production. Glycine and2,4-D had the highest (26.34%) and the lowest (8.33%) contribution to explaining embryonic callus induction, respectively. A widerange of responses (0 to 44.1 mg) were observed in the Plackett–Burman design with respect to the fresh weight. The regression analysisfor the Plackett–Burman design (PBD) demonstrated that glycine, sorbitol, and sucrose were of high influence on the fresh weight(P ≤ 0.05). Glycine (31.4%) and sucrose (6.7%) were found to have the highest and lowest contribution to the fresh weight of callus,respectively. Thus, this practical article seeks to show some helpful statistical approaches to typical problems in data analyses of tissue culture research.