Endogenous Hormones and Amino Acids Contents Influence Somatic Embryogenic Potential of Phoenix dactylifera L.

Abstract

Somatic embryogenesis is a means by which plants can regenerate bipolar structures from somatic cells. Furthermore, a high frequency and synchronous embryogenic system is necessary to obtain the complete advantages of somatic embryogenesis. Additionally, examining the regenerability of embryogenic callus (EC) and its ability to develop further into advanced stages of somatic embryos (SEs) could therefore help in the mass production of date palm SEs. For that reason; the embryogenic callus (EC), non-embryogenic callus (NEC) and the other developing SEs phases [pro-embryos (PE) and fully developed SEs (FDSEs)] were undergone to determine the endogenous plant growth regulators (PGRs) as well as different amino acids levels. Indole-3-acetic acid (IAA), gibberellic acid (GA3), zeatin (Z) and 2-isopentenyladenine (2iP) concentrations reached their lowest levels in EC in comparing with the other developing SEs phases (PE and FDSEs). However, NEC had the greatest level of ABA. Furthermore, FDSEs had high levels of GA3 and total cytokinins (CKs). In contrast to FDSEs and NEC, which had high 2iP/zeatin ratios, EC and PE had elevated IAA/CKs ratio. IAA/ABA ratio increased significantly in PE. On either hand, EC had the highest significant quantities of aspartic, alanine, histidine and lysine than PE and FDSEs. Whereas, NEC had the highest significant levels of glycine, tyrosine, and phenylalanine, but no proline was detected in NEC or PE. Serine, glutamic, and arginine levels were high in FDSEs. In PE, the level of threonine increased considerably. These determined biochemical components are highly of importance since the discovery that the induction and expression of somatic embryogenesis are totally dependent on their endogenous levels from PGRs and free amino acids.