Callus induction and organogenesis in soybean [Glycine max (L.) Merr.] cv. pyramid from mature cotyledons and embryos.

Abstract

Soybean is one of the most important legumes of the world. Soybean plants are affected by several biotic and abiotic factors as well as insect pests and diseases which lower the quality and production of the crop. In order to over- come these biotic and abiotic challenges, a systematic crop improvement plan has to be followed in order to enhance crop production which involves the use of new technologies and developing new cultivars with desirable qualities. With the completion of the soybean genome sequencing project, it is anticipated that access to desirable gene sequences will advance soybean improvement efforts. Two general approaches for in vitro plant regeneration are used; somatic embryo- genesis from immature embryos and organogenesis from mature parts of the plant and seeds. In vitro regeneration in soybean depends upon several physical, biochemical and genetic factors. Different genotypes respond differently to the method of regeneration used. Pyramid soybean is used in several breeding and mapping projects but does not have a regeneration procedure worked out. The goal of our project was to develop an in vitro regeneration procedure for soybean cv. Pyramid that would be amenable to genetic manipulations. We excised cotyledons and embryos from germinating seeds and induced callus with various concentrations of 2,4-D and NAA, used alone or in combination. 2,4-D at 3-21� M concentrations in the culture media produced 100% callus induction from cotyledons. After callus formation we trans- ferred them to BAP and Kinetin containing culture media and obtained roots and shoots; 5 � M BAP was the most effec- tive for that purpose. Fully developed plants were transplanted to the pots in less than three months where they produced healthy seeds in July.