Biochemical Changes in Embryogenic and Nonembryonic Callus of Glycyrrhiza glabra L. during Somatic Embryogenesis

Abstract

The continuous extraction of glycyrrhizin from Glycyrrhiza glabra L. has led to the critical endangerment of this therapeutic plant. Glycyrrhizin, a triterpenoid saponin, is a vital secondary metabolite renowned for its diverse pharmacological benefits, including anti-inflammatory, immunomodulatory, antiallergic, antiulcer properties, and even efficacy against HIV. However, the relentless harvesting of roots for high-value glycyrrhizin results in the obliteration of the entire plant, posing a severe threat to its existence and causing a detrimental impact on biodiversity. To counteract this challenge and conserve the species, sustainable approaches are imperative. One such approach involves the utilization of in vitro regeneration through somatic embryogenesis for clonal proliferation and genetic modification. This report presents findings on SE-associated proteins in Glycyrrhiza glabra L., accomplished through the implementation of the discontinuous gel electrophoresis technique. The study focused on a comparative isozyme analysis employing non-embryogenic and embryogenic calli of G. glabra L. Remarkably, these isozymes were exclusively identified and exhibited affiliations with a spectrum of cellular functions. A substantial portion of these proteins are engaged in a diverse range of metabolic and stress-related functions. This study utilized crude enzyme/total protein extracts as a basis to evaluate the genetic stability of in vitro cultivated plant tissue. Acid phosphatase, esterase, and peroxidase were selected as indicators for this assessment. Intriguingly, esterase and acid phosphatase exhibited significant polymorphism between the segregated embryogenic callus (EC) and non-embryogenic callus (NEC) derived from the same G. glabra L. genotype. Comparative analyses encompassing esterase, acid phosphatase, and peroxidase activities, alongside the expression profiles of these isozymes throughout somatic embryogenesis (SE), were conducted using polyacrylamide gel electrophoresis. Notably, the isoenzyme patterns of calluses were assessed. The activity of isozymes within an embryogenic line of callus surpassed that within a non-embryogenic counterpart. However, no conspicuous alterations in quality were observed between the non-embryogenic and embryogenic calluses.