Relationship between embryonic callus induction from leaves and endogenous hormone content in loquat (Eriobotrya japonica Lindl.)

To understand the relationship between endogenous hormone content during embryonic callus induction, somatic embryos were obtained by embryonic callus induction from loquat leaves. The content of four endogenous hormones, gibberellic acid (GA₃), auxin (IAA), abscisic acid (ABA) and zeatin (ZT), were analyzed by high performance liquid chromatography (HPLC). The dynamic changes of these endogenous hormones in embryonic calli were then explored. Results suggested that the ratio of IAA/ZT in leaves had a positive effect on embryonic callus induction, whereas GA₃/IAA had a negative effect. Low content of GA₃ and high content of IAA and ABA were required for embryonic calli induction, and a high ratio of IAA/ZT was advantageous to their formation. The timely addition of exogenous hormones in the late period of subculture was helpful for maintaining the embryo. This research provides a theoretical direction for explant selection, extraneous hormone addition to calli subculture, and successive transfer time selection, as well as a foundation for efficiently obtaining embryonic materials and developing the study of gene transformation.